Aims The Loess Plateau stands as one of China’s most susceptible regions to meteorological drought, a vulnerability exacerbated in recent years by the backdrop of climate warming. As meteorological droughts show a rising trend, investigating the capacity of vegetation to withstand and recover from drought stress becomes paramount. Understanding the resilience and resistance of vegetation’s photosynthetic physiological processes to drought is crucial for comprehending how vegetation responds to environmental shifts and for forecasting the future trajectory of vegetation development in the area.
Methods Utilizing the solar-induced chlorophyll fluorescence Global SIF dataset based on OCO-2 (GOSIF) products alongside temperature and standardized precipitation evapotranspiration index (SPEI) data, this study aims to investigate the impact of drought on the spatial and temporal stability of photosynthesis across various vegetation types and climate zones on the Loess Plateau employing the multiple linear autoregressive model.
Important findings The study revealed a linear relationship between vegetation photosynthetic resilience and the severity of drought experienced on the Loess Plateau. Vegetation photosynthetic resilience weakens in the order of mild, moderate, and severe drought. The relationship between vegetation photosynthetic resistance and drought severity exhibited a nonlinear pattern, with resistance declining from severe to mild and moderate drought. Vegetation photosynthesis on the Loess Plateau displayed insensitivity to temperature variations. Comparison across climatic zones highlighted that in arid regions, vegetation photosynthetic resilience declined with escalating drought severity, whereas semi-arid zones demonstrated relatively stable resilience. In semi-humid regions, vegetation photosynthetic resilience decreased in the order of severe, mild, and moderate droughts. Among vegetation types, forests demonstrated the highest levels of both resilience and resistance. These findings contribute significantly to our understanding of the regional vegetation stability in the Loess Plateau under the background of climate changes, thereby guiding the ecological restoration and management efforts in the region.

Aims Changes in precipitation characteristics, such as drought, prolonged dry season, and increased dry-wet alternation, lead to variations in plant functional traits. These changes trigger adjustments in the cooperative relationship of plant functional traits within a single organ or between multiple organs. Consequently, plant behavior and adaptation strategies change accordingly. However, the quantitative relationships and mechanisms behind this process are still unclear. This study aims to measure the specific responses of common species to climate across regions along a precipitation gradient, quantify the trait-environment relationship, elucidate the regulatory mechanism, and reveal the regional differentiation of functional traits and adaptation strategies of common species. This study will provide data support and solid scientific basis for climate management.

Methods The study focused on Ulmus pumila as the experimental subject. Ten sites were selected along a precipitation gradient from southeast to northwest China, where 28 functional traits of branches and leaves were measured. We analyzed the regional differentiation of branch and leaf traits, as well as their trade-offs. Furthermore, we quantified the regional differentiation of collaborative relationships among functional traits of branches and leaves along the precipitation gradient, revealing the adaptation strategies of U. pumila to varying moisture environments.

Important findings The results showed that: (1) In humid regions, U. pumila branches exhibited the highest hydraulic conductivity (K_s) and the lowest cavitation resistance (P₅₀); as precipitation decreased, leaf thickness and leaf tissue structure tightness increased, enhancing U. pumila’s drought resistance. (2) Across the entire precipitation gradient, there was an efficiency-safety trade-off within branches and between branches and leaves of U. pumila; however, at the regional scale, this trade-off relationship decoupled with decreasing precipitation. (3) Correlation analyses of branch and leaf functional traits revealed that, across the entire precipitation gradient, maximum net photosynthetic rate (P_n) and leaf mass per unit area were negatively correlated with K_s and positively correlated with P₅₀. Ulmus pumila regulated photosynthesis through coordinated adjustments of branch water transport capacity and leaf functional traits. The coordination and adjustment of branch and leaf functional traits are crucial mechanisms for U. pumila to adapt to varying moisture environments.

Aims The Rhododendron as a high ornamental value genus has a great potential for resources development and utilization in China, which provided the most abundant rhododendron resources in the world. The risk of drought stress is rapidly increasing in the context of global warming, but the effects of water stress on growth and physiological and ecological indexes of rhododendrons are still lacking. In this paper, the height and ground diameter growth increment of R. delavayi under the drought stress were studied, and the numerical relationship of the growth increment response to the physiological indicators were established to provide a theoretical basis for the future protection and management of rhododendron.
Methods Pots experiment with 2 years old seedlings of R. delavayi were carried out from March 11th to October 15th, 2022. The water stress gradient was set as 15%, 25%, 35%, 50%, 70%, 90% of the field water holding capacity respectively. The height and ground diameter of each R. delavayi were measured in early and late of March, April, May and in the middle of June, July and October. The physiological index of osmotic system (proline (Pro), soluble sugar (Ss), soluble protein (Sp) contents), antioxidant system (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activity, malondialdehyde (MDA) content) and photosynthesis system (net photosynthetic rate (P_n), stomatal conductance (g_s), intercellular CO₂ concentration (C_i), transpiration rate (T_r)) were measured in June, July, and August by randomly selecting five seedlings in each treatment.
Important findings 1) The equations of rhododendron height and ground diameter response to the day of year (DOY) were established under each drought gradient with the fitting accuracy between 0.94-0.99. The mortality was the highest under the treatment of 15% of the field water holding capacity. 2) The equations of the relative cumulative tree height response to the soil water content were established with the unimodal curve variation. While that of ground diameter response to the soil water content shows the U shape variation with the increase of soil water content before DOY 161, the linear pattern with that between DOY 161-201, and the unimodal curve variation after DOY 201. 3) With the increase of soil water content, SOD activity, CAT activity, POD activity, P_n, g_s, T_r and Pro content increased firstly and then decreased, the SOD activity, CAT activity, POD activity and Pro content reach the maximum value at field water holding capacity of 20%-30%, P_n, g_s and T_r reach that value at 60%-80%; MDA content gradually decreases; C_i, Ss and Sp contents decrease first and then increase, reaching the minimum value at field water holding capacity of 60%-80%. 4) Based on the regression analysis of the daily increment of ground diameter and the physiological indexes, the significant regression relationship index includes MDA content, P_n, g_s, T_r and Ss content. Except the relationship of daily ground diameter increment response to the MAD was quadratic function, the relationship of that to the other physiological indexes were power equation, the fitting accuracy of the relationships was T_r > P_n > MDA content > g_s > Ss content. The cumulative growth (diameter increment) of R. delavayi was the most when the soil content was 68% of the field water holding capacity. With the soil water varying, the growth was mainly promoted by T_r, P_n and g_s, but inhibited by Ss content. The MDA content promoted the growth when it was lower than 33.53 nmol∙g^-1, but it turned inhibited the growth when it was higher than 33.53 nmol·g^-1. This has further explained the physiological mechanism of R. delavayi seedlings growth.

INTRODUCTION: The CPSF family (cleavage and polyadenylation specificity factor) is a crucial protein family that is responsible for polyadenylation signal recognition in mRNA precursors, cleavage and the addition of poly(A) tails to mRNAs in plants. This family plays crucial roles in the regulation of flowering time, the environmental response, and seed development. Currently, the function of the CPSF family genes in Brassica napus is unclear.

 
RATIONALE: To explore the function and expression patterns of the CPSF gene family, this study cloned BnaA02.CPSF6 from B. napus variety Zhongshuang No.11 and conducted bioinformatics analysis, subcellular localization, expression pattern, and functional characterization of the gene.

 
RESULTS: These results indicate that the coding region of the BnaA02.CPSF6 gene is 1 938 bp in length and encodes 646 amino acids without intron structures. Its promoter region contains multiple cis-acting elements involved in light responses and MYB binding sites. Additionally, there are six genes homologous to BnaA02.CPSF6 in B. napus. The BnaA02.CPSF6 gene expressed in the roots, stems, leaves, flowers and different developmental seeds of B. napus, especially significantly higher in 15-35 d developmental seeds, and its encoded protein was localized in the nucleus. The BnaA02.CPSF6 gene expression is upregulated under salt and drought stress. Under treatment with hormones such as ABA, IAA, GA₃, SA, and MeJA, the expression of BnaA02.CPSF6 gene is initially inhibited and then gradually recovers to normal levels. Under normal conditions, the overexpression of the BnaA02.CPSF6 gene in Arabidopsis thaliana results in an early bolting phenotype, along with a reduced number of rosette leaves.

CONCLUSION: In summary, the above results indicate that the BnaA02.CPSF6 is involved in abiotic stress responses, is regulated by phytohormones, and may also play a promoting role in flowering regulation.

ABF transcription factors are collectively referred to as basic leucine zipper proteins that can specifically recognize and bind to ABA-responsive elements (ABRE), participating in ABA signal transduction and serving as regulators of ABA signal transcriptional responses. This study analyzed the protein encoded by the BnaABF2 gene in Brassica napus. Subcellular localization results showed that the BnaABF2 protein is localized in the nucleus. Analysis of transcriptional activity in the yeast system indicated that BnaABF2 has no transcriptional activation activity; qRT-PCR detection revealed that the expression level of BnaABF2 is highest in leaves. We also found that ABA treatment, simulated drought, and salt stress can induce the expression of BnaABF2; BiFC results showed that BnaMPK1/2/6/7/9/12/13 can interact with BnaABF2. Dual-LUC results suggested that BnaMPK7 may enhance the transcriptional regulation of BnaABF2 on downstream target genes through phosphorylation. This study initially explored the basic characteristics and interacting proteins of the transcription factor BnaABF2, providing theoretical guidance for understanding its functions and mechanisms.

With the global increase in tree mortality events caused by drought, there have been numerous reports on the mechanism of drought-induced tree mortality both domestically and internationally in recent years. However, the exact mechanism that causes tree mortality remains unclear, which increases the uncertainty of predicting the survival probability of forests under future climate changes. This review systematically analyzed the research progress related to tree death caused by extreme drought events, focusing the prediction of death point and physiological mechanism of drought-induced tree mortality. It highlighted that tree death was the result of multiple physiological processes. Furthermore, previous reports have shown that the death judged by visual symptoms may occur after the tree has already been dead for a period, leading to a lack of early warning signals and making the death inevitable. The review analyzed the main characteristics and possible sequence of physiological variables such as the degree of xylem embolism, radial flow, cell membrane permeability, and cambium activity in the process of drought-induced tree mortality. It suggests that the loss of cambium activity ultimately led to irreversible tree death. Therefore, when discussing the mechanism of drought-induced tree mortality, quantifying the loss rate of cambium activity is crucial for accurately determining the time of tree death, which is worth further studying. This paper also proposed relevant issues and research directions in the field of drought-induced tree mortality, providing reference ideas for accurately predicting tree death and formulating efficient and appropriate solutions to future climate change.

Aims As one of the important species in shelterbelt forests of the northern China, the large-scale decline of the Populus simonii has a serious impact on the healthy development of the ecosystem and the sustainable management of shelterbelt forests, and the investigation on the causes of P. simonii degradation in the context of climate change can provide a reference for the management of plantation forests.

Methods The study investigated three P. simonii plantation forests with different degradation levels in Zhangbei, and compared their basal area increment (BAI), intrinsic water use efficiency (iWUE), tree ring carbon stable isotopes ratio, and stomatal regulation strategies, in order to analyze the impacts of climate change on the growth of P. simonii and its intrinsic water use efficiency.

Important findings The results showed that: 1) CO₂ concentration and air temperature were the main drivers of iWUE changes, with a significant increasing trend in iWUE under the combined effects of increasing atmospheric CO₂ concentration, climate change and physiological conditions. 2) The tree growth in the three P. simonii stands with different levels of degradation was mainly determined by air temperature, and in most cases the increase in iWUE did not promote tree growth. 3) Declining trees were more sensitive to drought in the context of climate change, and more stringent stomatal strategies were adopted by highly degraded stands under drought stress. 4) The negative effects of increased drought stress on tree physiology could not be counteracted by increased CO₂ concentrations and increased air temperatures, and prolonged drought stress might lead to further decline in the growth of degraded trees.

Trade-offs have long been recognized as a crucial ecological strategy for plant species in response to environmental stresses and disturbances. However, it remains unclear whether trade-offs exist among different structures (or functions) of clonal plants in response to aeolian activities in sandy environments. We examined the growth (reproductive vs. vegetative), reproduction (sexual vs. asexual), and bud bank (tiller buds and rhizome buds, representing vertical and horizontal growth potential) characteristics of two dominant rhizomatous grasses (Psammochloa villosa and Phragmites australis) in the arid sand dunes of northwestern China. Our results showed that these two rhizomatous clonal species exhibited significant trade-offs in their adaptation strategies in response to changes in sand burial depth. Specifically, as sand burial depth increased, the clonal species tended to reduce their reproductive growth, sexual reproductive capacity, and horizontal growth potential, as evidenced by reductions in reproductive ramet number and proportion, panicles number, biomass, and their proportions, as well as rhizome bud number, biomass, and their proportions. Conversely, they increased vegetative growth, reproduction, and vertical growth potential, as evidenced by enhancements in vegetative ramet number and proportion, belowground bud number, biomass, and their proportions, and in tiller bud number, biomass, and their proportions. Our study underscores the importance of trade-offs in the adaptation strategies of rhizomatous clonal species in sandy environments where drought stress and aeolian disturbance coexist. Those trade-offs could ensure the population persistence and stability of pioneering psammophytes in sand dunes, which should be considered during sand-fixing and vegetation restoration efforts in arid sand dunes.

Aims The grasslands of Mongolian Plateau are the core of the Eurasian grassland ecosystem and serve as an important ecological barrier in northern China. Climate change has significantly increased the intensity, frequency, and duration of drought events across the Mongolian Plateau. Therefore, assessing the resistance and resilience of the Mongolian Plateau grasslands quantitatively helps deepen our understanding of their responses to climatic anomalies. However, few studies have explored how different grassland types on the Mongolian Plateau withstand consecutive droughts.
Methods In this study, we used long-term series data from 2000 to 2020 on the standardized precipitation evapotranspiration index (SPEI) and net primary productivity (NPP) to quantify the resistance and resilience of the Mongolian Plateau grassland ecosystem to consecutive droughts (1-4 a) and analyze its spatiotemporal variations. Furthermore, we compared the responses of three main types of grasslands (meadow steppe, typical steppe, and desert steppe) to extreme and moderate droughts.
Important findings Our results show that: (1) Grasslands generally exhibit higher resistance under moderate drought compared to extreme drought, except during two consecutive drought years. However, they are more resilient to extreme drought. (2) As the number of consecutive drought years increases, the resistance declines for both extreme and moderate droughts, while resilience initially increases under extreme drought but decreases under moderate drought. (3) Along the spatial gradient of decreasing precipitation, meadow steppe exhibits the highest resistance, followed by typical steppe, while desert steppe shows the lowest resistance. In contrast, desert steppe demonstrates the highest resilience, whereas meadow steppe has the lowest resilience. (4) Over time, the resistance of grasslands was higher from 2011-2020 compared to 2001-2010, while resilience was lower in the later period. As consecutive drought years increase, the resistance for all types of grasslands declines in both periods (2000-2010 and 2011-2020), while resilience initially increases (2000-2010) and then decreases (2011-2020). These insights are crucial for maintaining the Mongolian Plateau’s ecological barrier, ensuring its ecological services, and supporting both regional and global ecological security and sustainable development.

INTRODUCTION Tomato (Solanum lycopersicum), a significant warm-season and water-dependent vegetable crop, is extensively cultivated worldwide. Whether grown in open fields or protected environments, tomatoes frequently encounter various environmental stresses, including drought and low temperatures, which significantly impact their yield and quality. Transcription factors play a pivotal role in plant stress responses by modulating the expression of specific target genes, thereby transmitting perceived stress signals downstream. WRKY transcription factors in tomatoes are known to regulate responses to multiple abiotic stresses. However, the specific role of the tomato SlWRKY45 in abiotic stress responses remains unclear.

RATIONALE Studies have demonstrated that WRKY transcription factors play a crucial regulatory role in plant responses to abiotic stress. As an important economic vegetable crop, tomato is susceptible to various environmental stresses during its growth and development. By genetically overexpressing SlWRKY45 in tomato and investigating its function under low-temperature and drought stress conditions, the findings can provide a theoretical foundation for understanding the complex regulatory mechanisms of WRKY transcription factors. Additionally, this research offers valuable candidate genes for breeding stress-resistant tomato varieties.

RESULTS Expression analysis revealed that low-temperature, drought, and abscisic acid (ABA) treatments significantly induced the expression of SlWRKY45. Overexpression of SlWRKY45 enhanced the resistance of tomato plants to drought and low-temperature stresses. Under drought and low-temperature conditions, the photosynthetic indices, antioxidant enzyme activities, and proline (Pro) contents in SlWRKY45 overexpression lines were significantly higher than those in wild-type (WT) plants. Conversely, the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) levels in SlWRKY45-OE plants was significantly lower than in WT plants under the same stress conditions. Transcriptome data analysis indicated that SlWRKY45 regulates tomato's response to low-temperature stress primarily by influencing antioxidant enzyme activities and stress response pathways. Dual-luciferase assays demonstrated that SlWRKY45 could directly activate the expression of SlPOD1. Furthermore, the interaction between SlWRKY45 and SlWRKY46 was confirmed through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays.

CONCLUSION Our findings demonstrate that SlWRKY45 positively regulates drought resistance and low-temperature tolerance in tomato. Additionally, SlWRKY45 can interact with SlWRKY46 and directly activate the expression of SlPOD1. These results offer valuable insights for further research into the regulatory mechanisms underlying abiotic stress responses and provide potential gene resources for genetic improvement through molecular breeding.

Phenotypes of SlWRKY45-overexpressing and wild-type plants under drought and low-temperature treatments

The ecologically fragile arid valleys in western China have low afforestation survival rates, and the lack of adaptable superior variety is key to restricting forestry production and ecological restoration in this region. The native poplar trees are important germplasm resources in this region, with a wide range of taxa, rich genetic variations, and great potential for breeding and utilization. Six clones of native poplars were used in a field trial to investigate variations in survival, growth and adaptation to arid-warm and arid-hot valleys. In the arid-hot valley, clone Y1-2 exhibited the highest survival rate and growth condition, surpassing other clones, while clones B7-4 and P3-6 demonstrated superior survival and growth performance in the arid-warm valley. Clone B7-4 displayed the highest soluble sugar content in leaves across both habitats. Superoxide dismutase and ascorbate peroxidase activities, along with malondialdehyde content in leaves, were higher in the arid-hot valley for all clones compared with the arid-warm valley. Long-term water use efficiency, as indicated by δ¹³C in leaves, was significantly higher for all clones in the arid-hot valley, particularly for H1-6, T3-2 and P3-6. Increases in upper epidermis thickness were observed in clones E1, B7-4 and P3-6, while Y1-2 exhibited a higher palisade parenchyma thickness (PT) in the arid-hot valley compared with the arid-warm valley. Vein densities were higher in leaves of clones E-1, B7-4, Y1-2 and P3-6 in both valleys compared with other clones, with B7-4 showing a significant increase in mean vein width in the arid-hot valley. In conclusion, the superior growth performance of clone B7-4 in the arid-warm valley may be attributed to its stronger osmotic adjustment and higher capacity to maintain water transportation through venation. The exceptional performance of clone Y1-2 in the arid-hot valley may be associated with its compact arrangement of PT, as well as its stronger capacity for hydraulic transport and antioxidant resistance in leaves.

When and how disjunct distributions of biological taxa arose has long attracted interest in biogeography, yet the East Asian–Tethyan disjunction is understudied. Cupressus (Cupressaceae) shows this disjunction, with 10 species in East Asia and three in the Mediterranean region. Here we used target-capture sequencing and obtained 1991 single-copy nuclear genes, plus complete plastomes, to infer the evolutionary history of Cupressus. Our phylogenomic reconstruction resolved four well supported clades in Cupressus, but revealed significant phylogenetic conflicts, with inter-lineage gene flow, incomplete lineage sorting and gene tree estimation error all making important contributions. The Chengiana clade most likely originated by hybridization between the ancestors of the Himalayan–Hengduan Mountains and subtropical Asia clades, whereas orogenic and climatic changes may have facilitated gene flow within the Himalayan–Hengduan Mountains clade. Molecular dating suggested that the most recent common ancestor of Cupressus appeared in East Asia around the middle Eocene period and then became continuously distributed across Eurasia. The East Asian–Tethyan disjunction arose when the Mediterranean and Himalayan–Hengduan Mountains clades diverged, likely to have been driven by Eocene/Oligocene declines in global temperature, then reinforced by the ecogeographic barrier created by the uplift of the Qinghai–Tibet Plateau. Niche shifts in the common ancestor of the Mediterranean clade, and signatures of selection in genes for drought and salt tolerance, probably indicate adaptation of this clade to local conditions. Overall, our study suggested that in-depth phylogenomic analyses are powerful tools in deciphering the complex evolutionary history of the origin of East Asian–Tethyan disjunction of organisms, especially gymnosperms.

Aims Examining how water use efficiency (WUE) in plantations responds to environmental factors is crucial for understanding vegetation's water strategies and assessing ecosystems' carbon and water recycling capacity. Methods Utilizing eddy covariance flux data alongside concurrent meteorological data from the National Posi-tioning Observation and Research Station of Eucalypt Plantation Ecosystem, spanning the years 2018 to 2022, this study conducted an analysis of the temporal variations and seasonal differences in WUE within the Eucalyptus plantation ecosystem. The analytical methods employed included stepwise regression analysis, path analysis, and redundancy analysis. An investigation was conducted to examine the relationship between WUE and various envi-ronmental factors, with a particular focus on the distinctions between drought and rainy seasons, as well as the primary factors influencing these variations. Important findings (1) Throughout the observation period, the mean WUE of the Eucalyptus plantation ecosystem was recorded at 3.85 g C·kg–1 H2O during the dry season (November to April) and 2.61 g C·kg–1 H2O during the rainy season (May to October). The annual mean WUE was determined to be 3.22 g C·kg–1 H2O. (2) WUE exhibited distinct diurnal variation patterns, with similar trends observed during both the dry and rainy seasons. A significant negative correlation was identified between diurnal WUE and variables such as vapor pressure deficit (VPD), air temperature (Tair), soil temperature (Tsoil), photosynthetically active radiation (PAR), and soil moisture (SM). Furthermore, stepwise regression analysis indicated that VPD serves as the primary environmental factor influencing the diurnal variation of WUE. (3) The temporal variation of daily scale WUE exhibited an inverse relationship with gross primary productivity (GPP) and evapotranspiration (ET). Path analysis indicated that WUE is predominantly influenced by direct negative impacts from VPD and Tsoil, in addition to indirect negative influences from PAR. The responses of WUE to VPD and Tsoil demonstrated significant discrepancies between dry and rainy seasons, while the seasonal responses to PAR were found to be consistent. (4) On a monthly basis, WUE was predominantly influenced by temperature and VPD during the dry season, while PAR played a significant role in the rainy season. The vari-ations in WUE across different seasons were primarily influenced by alterations in ET, which were governed by temperature, VPD, and PAR. The WUE of the Eucalyptus plantation ecosystem exhibited marked variations between the drought and rainy seasons, with the primary controlling factors differing according to the temporal scale.

Members of the cyclic nucleotide-gated channel (CNGC) proteins are reportedly involved in a variety of biotic and abiotic responses and stomatal movement. However, it is unknown if and how a single member could regulate multiple responses. Here we characterized three closely related CNGC genes in rice, OsCNGC14, OsCNGC15 and OsCNGC16, to determine whether they function in multiple abiotic stresses. The loss-of-function mutants of each of these three genes had reduced calcium ion (Ca²⁺) influx and slower stomatal closure in response to heat, chilling, drought and the stress hormone abscisic acid (ABA). These mutants also had reduced tolerance to heat, chilling and drought compared with the wild-type. Conversely, overexpression of OsCNGC16 led to a more rapid stomatal closure response to stresses and enhanced tolerance to heat, chilling and drought. The tight association of stomatal closure and stress tolerance strongly suggests that tolerance to multiple abiotic stresses conferred by these OsCNGC genes results at least partially from their regulation of stomatal movement. In addition, physical interactions were observed among the three OsCNGC proteins but not with a distantly related CNGC, suggesting the formation of hetero-oligomers among themselves. This study unveils the crucial role of OsCNGC14, 15 and 16 proteins in stomatal response and tolerance to multiple stresses, suggesting a mechanism of tolerance to multiple stresses that involves calcium influx and stomatal movement regulation.

Aims Drought effects on the carbon (C) balance are considered the major factor of tree mortality and are assumed to be regulated by soil nutrient (e.g., nitrogen (N)) availability. However, the effects of nitrogen addition on trees’ carbon and nitrogen distribution between aboveground and belowground and the coupling between carbon and nitrogen relations in various organs in response to drought are still unclear in trees.
Methods A two-year full factorial microcosm experiment was set up with sessile oak (Quercus petraea). Nitrogen addition was performed in the first year, and a drought treatment was conducted in the second year. Isotope ¹⁵N and ¹³C labelling were carried out before drought and during drought, respectively. Three consecutive samplings were conducted after the dual labelling with ¹³C and ¹⁵N in the second year, and the effects of nitrogen addition on carbon and nitrogen allocation dynamics during progressive drought were tested.
Important findings Our results showed that previous nitrogen addition promoted photosynthetic carbon fixation and nitrogen allocation, increased root nitrogen uptake, reduced the non-structural carbohydrates (NSC) contents in all organs and changed the relationships of carbon and nitrogen in aboveground and belowground organs. In contrast, drought had minor effects on nitrogen and carbon allocation between aboveground and belowground and the relationship of carbon with nitrogen in all organs (represented by the ratio of ¹³C to ¹⁵N in all organs). Drought only significantly reduced the content of NSC. During drought (from day 40 to 73), previous nitrogen addition led sessile oak to prioritise belowground carbon and nitrogen allocation. Our results indicate that sessile oak can change its carbon and nitrogen allocation strategies to adapt to drought, while previous nitrogen addition may increase its drought sensitivity.

Aims Populus euphratica and Tamarix ramosissima are two dominant species in the Daliyaboyi oasis, located at the tail of the Keriya River in the hinterland of the Taklamakan Desert. Against the backdrop of a warming and wetting climate trend in Northwest China, the relationship between the radial growth of these two species and climate change remains unclear. This study aimed to identify the limiting factors for the radial growth of P. euphraticaand T. ramosissima and to examine the characteristics of their growth-climate relationships in the conditions of a warming and wetting climate.

Methods Tree-ring samples of P. euphraticaand T. ramosissima were collected from two sites with different groundwater depths (1.0 m and 4.4 m) at the Daliyaboyi oasis. Standard chronologies were established for the two species, and the relationships between tree-ring width index and runoff and climatic factors for both species were analyzed. The differences in the climate responses of these two species were also explored.

Important findings The results indicated that P. euphratica and T. ramosissima with different groundwater depths have different responses to climate factors. With a groundwater depth of 1.0 m, the radial growth of P. euphratica was significantly and positively correlated with precipitation in April of the previous year and April of the current year. Meanwhile, the radial growth of T. ramosissima was significantly and positively correlated with runoff in June of the previous year and precipitation in February of the current year, and was significantly and negatively correlated with air temperature in December of the previous year. With a groundwater depth of 4.4 m, the radial growth of P. euphratica was significantly and positively correlated with air temperatures in January of the previous year and January of the current year, as well as with the Palmer Drought Severity Index (PDSI) from January of the previous year to June of the current year and from August to September of the current year. Meanwhile, the radial growth of T. ramosissima was significantly and positively correlated with runoff in June of the previous year, temperatures in September of the previous year, and precipitation in December of the previous year, as well as with temperatures in April of the current year. Sliding correlation analysis suggested that, under the influence of climate warming and wetting in the Taklamakan Desert, the positive response of P. euphratica radial growth to runoff factors (January to March) weakened at a groundwater depth of 1.0 m. In contrast, T. ramosissima showed an increased positive response to precipitation in April of the previous year and runoff from January to February of the previous year. With a groundwater depth of 4.4 m, the radial growth of P. euphratica showed a shift from a positive to a significant negative correlation with air temperature during April to May and July to August of the previous year, as well as during April to May and July to August of the current year, and the relationship between radial growth of P. euphratica to PDSI changed from significant positive correlation to non-significant correlation. The relationship between radial growth of T. ramosissima and precipitation and PDSI changed from negative correlation to positive correlation. In conclusion, P. euphratica demonstrates greater dependence on long-term climate factors at the deep groundwater depth, while T. ramosissima is more sensitive to short-term hydrological factors.

INTRODUCTION: Plant roots respond to various abiotic stresses, including drought stress, heavy metal stress, salt stress, and deficiencies in essential nutrients, during their growth and development. Among these factors, soil structure, especially soil compaction, significantly affects root growth and morphology, ultimately influencing crop yield.

RATIONALE: The Golgi apparatus plays a role in root growth and responds to abiotic stress through vesicle secretion. However, the mechanisms by which the Golgi apparatus contributes to the response of the root system to soil compaction remain unclear. Previous studies have demonstrated that AtFTCD-L in Arabidopsis is located on the trans-Golgi network (TGN) opposite the Golgi apparatus, and plays a role in vesicle sorting and/or secretion regulation of mucin components in the peripheral cells of the root cap.

RESULTS: Compared with those of the wild type, the root tips and root tip cells of the ftcd mutant are shorter in the longitudinal direction, but wider in the transverse direction, indicating abnormal cell morphology. Analysis of fluorescent signals from PIN-GFP plants revealed that PIN7 was either not expressed or expressed at very low levels in mutants. This study provides theoretical insights into the adaptive mechanisms of plant roots in response to abiotic stress induced by soil compaction.

CONCLUSION: In summary, AtFTCD-L responds to soil compaction in the roots of Arabidopsis by regulating the distribution or expression of PIN7.

Phenotypic differences in the effects of soil compaction on AtFTCD-L (WT)-, and mutant (ftcd)-mediated PIN7 regulation of root cell growth. The growth phenotypes of the root tips of the Arabidopsis lines on the 7^th day.

The saline and alkaline land in Xinjiang is vast， and clarifying the characteristics of carbon， nitrogen and phosphorus stoichiometric cycles between organs and soil in the native drought-resistant and saline-tolerant Elaeagnus angustifolia forests in Xinjiang is of great significance in promoting the construction of desert， saline and alkaline vegetation and ecological restoration in the middle and lower reaches of the Tarim River. The E. angustifolia forests（E.moorcroftii and E. angustifolia） in the lower reaches of Tarim River were taken as materials， and the stoichiometric characteristics of different organs（leaves， branches， roots） and soils of two tree species in the forest and their interrelationships were analyzed， respectively. The results showed that： （1）The average content of carbon， nitrogen， and phosphorus in the leaves of E. angustifolia forests were 424.36-484.40 g⋅kg^-1， 33.83-38.71 g⋅kg^-1 and 1.50-2.20 g⋅kg^-1， respectively， and with moderate C and N contents and slightly low P content. The N∶P ratios of E.moorcroftii（17.64） and E. angustifolia（22.82） were higher than 16， indicating the growth limited by P. （2）There were significant differences in ecological stoichiometric characteristics of each organ in the E. angustifolia forests， and the contents of N and P were the largest in leaves. （3）The soil elements content of the E. angustifolia forests were significantly affected by soil depth， showing a vertical decrease along the soil profile and presenting a certain enrichment in the surface layer （0-20 cm）. The C∶N， C∶P and N∶P of the 0-60 cm soil layer were 17.94， 9.32 and 0.62， respectively， and the mineralization capacity of soil N element was weak， and N was deficient. （4）Soil N and P contents of E. angustifolia forests were significantly positively correlated with root N and P contents（P<0.05）， leaf N contents were significantly negatively correlated with 0-20 cm soil C and N contents of each layer（P<0.05）， and significantly positively correlated with soil P contents； leaf P contents were significantly and positively correlated with soil P contents of each layer， and there was no significant correlation between leaf C with soil C（P>0.05）. In general， in poor and severe saline-alkaline soils， the E. angustifolia forests stored less nutrients in branches and roots and usually supplied preferentially nutrients to leaves， the upper part of the E. angustifolia forests was mainly limited by P， and the underground part was mainly limited by N. Therefore， the overall nutrient cycling in E. angustifolia forests was limited by N and P elements.

In recent years， frequent extreme weather and uneven distribution of rain have caused water shortage in the key growth period of Codonopsis pilosula， leading to declines in quality and yield. To solve this problem， this study used Codonopsis pilosula as the object， investigated the regulatory effects of C. pilosula polysaccharides（CPPs） synthesis under drought stress by siliconaddition based on glycolysis （EMP） and tricarboxylic acid cycle（TCA）. Three groups were set up： water（CK）， drought by 15% PEG-6000（D） and drought by 15% PEG-6000 after silicon treatment（Si+D）. In Si+D group， 200 mL of 2 mmol⋅L^-1 potassium silicate solution was applied to each basin on the 7th day before drought treatment. EMP and TCA-related substances， enzymes activity and key genes expression were measured at 7， 14 and 21 days respectively after drought treatment. Meanwhile， the contents of CPPs and its biosynthesis-related substances were measured to analyze comprehensively the regulation of CPPs synthesis by silicon under drought stress. The results showed that： （1） Drought stress weakened the content of photosynthetic pigment of C. pilosula， accelerated the consumption of sucrose， fructose and glucose， and enhanced the energy consumption in EMP and TCA pathways for the synthesis and accumulation of starch and polysaccharide， and there was a mutual fluctuation of yield and quality. （2） The silicon addition enhanced the content of relative leaf water of C. pilosula， inhibited the content of photosynthetic pigments， increased the sucrose and fructose contents， decreased the enzymes activity related to starch synthesis and increased the enzymes activity related to starch decomposition， resulting in the decrease of starch and polysaccharide contents， but the overall yield of C. pilosula were increased. Silicon addition promoted the EMP pathway of C. pilosula under drought stress， prevented the TCA cycle process， and made pyruvic acid， the end product of EMP， synthesize into citric acid and its accumulation. The application of silicon might affect the photosynthesis of C. pilosula， regulate the energy generation and distribution of EMP and TCA pathways， enhance the ability of C. pilosula to resist drought， and play a positive role in the synthesis of polysaccharide and the quality and yield of C. pilosula. However， with the extension of drought stress time， the regulation effect was weakened gradually.

Reactive oxygen species (ROS) plays critical roles in modulating plant growth and stress response and its homeostasis is fine tuned using multiple peroxidases. H₂O₂, a major kind of ROS, is removed rapidly and directly using three catalases, CAT1, CAT2, and CAT3, in Arabidopsis. Although the activity regulations of catalases have been well studied, their degradation pathway is less clear. Here, we report that CAT2 and CAT3 protein abundance was partially controlled using the 26S proteasome. To further identify candidate proteins that modulate the stability of CAT2, we performed yeast-two-hybrid screening and recovered several clones encoding a protein with RING and vWA domains, CIRP1 (CAT2 Interacting RING Protein 1). Drought and oxidative stress downregulated CIRP1 transcripts. CIRP1 harbored E3 ubiquitination activity and accelerated the degradation of CAT2 and CAT3 by direct interaction and ubiquitination. The cirp1 mutants exhibited stronger drought and oxidative stress tolerance, which was opposite to the cat2 and cat3 mutants. Genetic analysis revealed that CIRP1 acts upstream of CAT2 and CAT3 to negatively regulate drought and oxidative stress tolerance. The increased drought and oxidative stress tolerance of the cirp1 mutants was due to enhanced catalase (CAT) activities and alleviated ROS levels. Our data revealed that the CIRP1–CAT2/CAT3 module plays a vital role in alleviating ROS levels and balancing growth and stress responses in Arabidopsis.

NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) are a family of plant-specific TFs that play crucial roles in various aspects of plant development and stress responses. Here, we provide an in-depth review of the structural characteristics, regulatory mechanisms, and functional roles of NACs in different plant species. One of the key features of NACs is their ability to regulate gene expression through a variety of mechanisms, including binding to DNA sequences in the promoter regions of target genes, interacting with other TFs, and modulating chromatin structure. We discuss these mechanisms in detail, providing insights into the complex regulatory networks that govern the activity of NACs. We explore the diverse functions of these TFs in plant growth and development processes, including embryogenesis, seed development, root and shoot development, floral development and fruit ripening, secondary cell wall formation, and senescence. We also discuss the diverse regulatory roles of NACs in response to various stresses, including drought, flooding, heat, cold, salinity, nutrient deficit, and diseases. Lastly, we emphasize the crosstalk role of NACs between developmental processes and stress responses. This integrated perspective highlights how NACs orchestrate plant growth and resilience. Overall, this review provides a comprehensive overview of the pivotal roles of NACs in plant development and stress responses, emphasizing their potential for engineering stress-resistant crops and enhancing agricultural productivity.

Plant root-associated fungal communities play a pivotal role in enhancing plant growth, nutrient absorption, disease resistance and environmental stress adaptation. Despite their importance, the assembly processes of these communities remain inadequately explored. In this study, we utilizzzed high-throughput sequencing, co-occurrence network analysis and null models to examine the diversity, composition, interaction patterns and assembly mechanisms of the root-associated fungal communities of Mussaenda pubescens, a drought-tolerant shrub that thrives in stressful environments and is widely used for Chinese medicine. Our findings revealed pronounced regional and ecological niche-based variations in the diversity and assembly of total fungi and essential functional guilds, including saprotrophs, symbiotrophs and plant pathogens. Significantly, the fungal diversity of plant pathogens decreased with elevation, whereas total fungi, saprotrophs and symbiotrophs were minimally affected. Stochastic processes, such as dispersal limitation, played a significant role in fungal assembly. Furthermore, soil physicochemical properties, climatic conditions and spatial variables emerged as critical determinants of fungal community structure. This study enriches our understanding of the dynamics governing root-associated fungal community assemblies and underscores the factors essential for sustaining fungal diversity.

Plants have co-evolved with a wide range of microbial communities over hundreds of millions of years, this has drastically influenced their adaptation to biotic and abiotic stress. The rapid development of multi-omics approaches has greatly improved our understanding of the diversity, composition, and functions of plant microbiomes, but how global climate change affects the assembly of plant microbiomes and their roles in regulating host plant adaptation to changing environmental conditions is not fully known. In this review, we summarize recent advancements in the community assembly of plant microbiomes, and their responses to climate change factors such as elevated CO₂ levels, warming, and drought. We further delineate the research trends and hotspots in plant–microbiome interactions in the context of climate change, and summarize the key mechanisms by which plant microbiomes influence plant adaptation to the changing climate. We propose that future research is urgently needed to unravel the impact of key plant genes and signal molecules modulated by climate change on microbial communities, to elucidate the evolutionary response of plant–microbe interactions at the community level, and to engineer synthetic microbial communities to mitigate the effects of climate change on plant fitness.

INTRODUCTION: 14-3-3 proteins are a highly conserved protein family that specifically recognize phosphorylated target proteins and play crucial roles in plant abiotic stress responses. By interacting with AREB/ABF (ABA-responsive element binding protein/ABA-responsive element binding factor) transcription factors, 14-3-3 proteins participate in ABA signal transduction and regulate abiotic stress tolerance. TaGRF3-D is a 14-3-3 protein gene in wheat (Triticum aestivum), and our previous studies revealed that the expression of this gene was upregulated under ABA and abiotic stress.
RATIONALE: To explore the biological function of the TaGRF3-D gene, we cloned the gene, and investigated its subcellular localization and function under drought stress.
RESULTS: The results revealed that TaGRF3-D is highly conserved in monocotyledonous plants and is localizes in the nucleus and plasma membrane. Compared with the wild type, the Arabidopsis thaliana transgenic lines overexpressing TaGRF3-D presented significantly longer roots under PEG and ABA treatments and showed a markedly greater survival rate after drought stress. Yeast two-hybrid analysis revealed that TaGRF3-D interacted with wheat TaABF3-B, TaABF4-A, TaABF15-D, TaABF16-B, TaABF17-D, and TaABF18-B, but not with TaABF1-D, TaABF2-A or TaABF19-A.
CONCLUSION: These results suggest that TaABF3-D responds to ABA signaling by interacting with wheat TaABF transcription factors, thereby increasing the drought stress tolerance of transgenic plants.

Phenotypes of the TaGRF3-D transgenic lines and the wild type (WT) under drought stress (A) and interaction between the TaGRF3-D protein and the ABF protein (B). Bars=1 cm

Maize (Zea mays L.) growth and yield are severely limited by drought stress worldwide. Stomata play crucial roles in transpiration and gas exchange and are thus essential for improving plant water-use efficiency (WUE) to help plants deal with the threat of drought. In this study, we characterized the maize dsd1 (decreased stomatal density 1) mutant, which showed defects in stomatal development, including guard mother cell differentiation, subsidiary cell formation and guard cell maturation. DSD1 encodes the basic helix-loop-helix transcription factor INDUCER OF CBF EXPRESSION b (ZmICEb) and is a homolog of ICE1 in Arabidopsis (Arabidopsis thaliana). DSD1/ZmICEb is expressed in stomatal file cells throughout stomatal development and plays a conserved role in stomatal development across maize and Arabidopsis. Mutations in DSD1/ZmICEb dramatically improved drought tolerance and WUE in maize and reduced yield losses under drought conditions. Therefore, DSD1/ZmICEb represents a promising candidate target gene for the genetic improvement of drought tolerance in maize by manipulating stomatal density.

Aims Grassland plant roots and mycorrhizal fungi are the main sources of soil organic carbon, which play an important role in the formation and turnover of soil organic carbon and its components, and they also affect the soil nitrogen pool. Under the scenario of climate change, global drought events are frequent. How drought affects the role of roots and mycorrhizal fungi on soil carbon and nitrogen pools of different components is still unclear.
Methods In this study, Cleistogenes squarrosa was planted in indoor pots and subjected to control and drought treatments. Root bags and mycorrhizal bags were set up to distinguish the effects of plant roots and mycorrhizal fungi on the carbon and nitrogen content of soil organic matter and its components during plant growth. After 64 days of plant growth, the plants were harvested. The soil inorganic nitrogen content, plant biomass, plant leaf carbon and nitrogen content, carbon and nitrogen content of soil organic matter and its components in root bags and mycorrhizal bags, and microbial community composition were measured.
Important findings The results showed that compared with mycorrhizal bags without root participation, the soil organic carbon and particulate organic carbon content in the root bags enhanced by 17.5% and 55.8%, and the mineral-associated organic nitrogen content increased by 10.1%. Drought treatment increased soil inorganic nitrogen content, reduced plant biomass, had no significant effect on the carbon and nitrogen content of soil organic matter and its components in the root bag, but significantly reduced the content of particulate organic carbon in the mycorrhizal bag. Drought treatment did not significantly change the microbial biomass in the root bag, but increased the microbial biomass in the mycorrhizal bag. The particulate organic carbon content in the mycorrhizal bags was negatively correlated with the amount of mycorrhizal fungi and the total microbial biomass. The results showed that during plant growth, the roots mainly affected the content of particulate organic carbon in the soil, and mycorrhizal fungi mainly affected the content of mineral-associated organic nitrogen. Short-term drought reduced the content of particulate organic carbon in the soil where mycorrhizal fungi were present. Future research should pay more attention to how global change affects the relative contributions of grassland plant roots and mycorrhizal fungi to soil organic matter and its components and their potential impact on soil organic carbon and nitrogen on a long-term scale.

Aims: The combined impacts of climate change and human activities are likely to increase the land areas suitable for poisonous weeds, leading to rapid biodiversity loss and increasingly severe grassland degradation in the semi-arid region of Xinjiang. Enhanced understanding of the relationship between soil biomes and ecosystem multifunctionality can provide theoretical support for efforts to control the spread of poisonous weeds in Xinjiang.
Methods: This study used a field experiment to explore the effects of nitrogen, water addition and mowing on soil biodiversity patterns, co-occurrence networks, and the relationship between diversity indices and ecosystem multifunctionality. This study adopted a randomized block trial design and set up eight treatments, which are no nitrogen, no watering, no mowing (CK), nitrogen addition (N treatment), watering (W treatment), mowing (M treatment), nitrogen × watering (NW treatment), nitrogen × mowing (NM treatment), watering × mowing (WM treatment), nitrogen × watering × mowing (NWM treatment).
Results: (1) The Shannon-Wiener diversity index of soil bacteria differed significantly between the control, water addition, and nitrogen-mowing treatments. There were no significant differences between the diversity of soil fungi, nematodes, and arthropods in each treatment. (2) N, W, M, NW, and NM treatments all resulted in reduced complexity and connectivity of soil biological co-occurrence networks. WM and NWM treatments increased the complexity and connectivity of soil biological co-occurrence networks. (3) In the control, there was a significant and positive correlation between multidiversity and ecosystem multifunctionality (P < 0.01). In the NM treatment, there was a significant and negative correlation between multidiversity and ecosystem multifunctionality (P < 0.05). There was no correlation between multidiversity and ecosystem multifunctionality in the other treatments. Finally, soil bacterial diversity was most susceptible to the change of external environment.
Conclusion: This study demonstrated that short-term nitrogen addition, watering, and mowing can weaken the relationship between soil biodiversity and ecosystem multifunctionality. These findings provide a theoretical basis for closer study of the mechanisms that affect the relationship between soil biodiversity and ecosystem multifunctionality through environmental changes caused by global climate change.

The black wolfberry (Lycium ruthenicum; 2n = 2x = 24) is an important medicinal plant with ecological and economic value. Its fruits have numerous beneficial pharmacological activities, especially those of anthocyanins, polysaccharides, and alkaloids, and have high nutritional value. However, the lack of available genomic resources for this species has hindered research on its medicinal and evolutionary mechanisms. In this study, we developed the telomere-to-telomere (T2T) nearly gapless genome of L. ruthenicum (2.26 Gb) by integrating PacBio HiFi, Nanopore Ultra-Long, and Hi-C technologies. The assembled genome comprised 12 chromosomes with 37,149 protein-coding genes functionally annotated. Approximately 80% of the repetitive sequences were identified, of which long terminal repeats (LTRs) were the most abundant, accounting for 73.01%. The abundance of LTRs might be the main reason for the larger genome of this species compared to that of other Lycium species. The species-specific genes of L. ruthenicum were related to defense mechanisms, salt tolerance, drought resistance, and oxidative stress, further demonstrating their superior adaptability to arid environments. Based on the assembled genome and fruit transcriptome data, we further constructed an anthocyanin biosynthesis pathway and identified 19 candidate structural genes and seven transcription factors that regulate anthocyanin biosynthesis in the fruit developmental stage of L. ruthenicum, most of which were highly expressed at a later stage in fruit development. Furthermore, 154 potential disease resistance-related nucleotide-binding genes have been identified in the L. ruthenicum genome. The whole-genome and proximal, dispersed, and tandem duplication genes in the L. ruthenicum genome enriched the number of genes involved in anthocyanin synthesis and resistance-related pathways. These results provide an important genetic basis for understanding genome evolution and biosynthesis of pharmacologically active components in the Lycium genus.

During the restoration of degraded ecosystems, different shrub species often segregate along environmental water gradients. However, the physiological mechanisms driving this segregation remain unclear. To address this gap, we conducted a drought stress experiment (70%–80% field water holding capacity, CK; 40%–50% field water holding capacity, MD; 20%–30% field water holding capacity, SD) to explore the physiological mechanisms driving the dominance of different shrub species at various stages of ecosystem restoration. Salix gordejevii, a species dominant in the early stages of restoration with high water availability, and Caragana microphylla, a species dominant in the later stages under low water availability, were studied. The results showed that the living state index (LSI) of S. gordejevii was significantly lower than that of C. microphylla under drought stress (P < 0.05). Differences in plant hydraulics and water-use strategies explained how these species adapt to varying soil moisture conditions. Salix gordejevii employed a proactive water-use strategy with lower water-use efficiency (WUE) and reduced resistance to xylem embolism (xylem water potentials corresponding to 50% loss of conductivity, P₅₀), making it better suited to environments with more abundant water. In contrast, C. microphylla adopted a conservative water-use strategy. This strategy was characterized by increased WUE and enhanced resistance to drought-induced xylem embolism, which allowed it to thrive under more drought-prone conditions. Importantly, hydraulic efficiency (⁠K_leaf, K_s, and K₁) emerged as the primary determinant of living state in both S. gordejevii (47.30%) and C. microphylla (62.20%). The lower embolism resistance of S. gordejevii (⁠P₅₀ = 1.3 MPa) made it more susceptible to xylem cavitation, leading to a decline in hydraulic efficiency under SD. In contrast, C. microphylla’s higher embolism resistance (⁠P₅₀ = 2.3 MPa) enabled it to maintain stable hydraulic conductance across all drought treatments. These differences in hydraulic efficiency, driven by xylem embolism resistance, were key factors influencing shifts in shrub dominance during ecosystem restoration. These findings provide a physiological explanation for the replacement of shrub species during ecosystem restoration, where soil moisture is the main limiting factor.

This study used a method based on a spatial series in place of a temporal series, selecting Tamarix ramosissima shrubs at different developmental stages of coppice dunes as research subjects to investigate their chlorophyll fluorescence characteristics and non-structural carbohydrates (NSC). The results indicated that: (1) As coppice dunes developed, T. ramosissima showed a significant increase in photosynthetic pigment content alongside a decrease in actual photochemical efficiency (Y_(II)). Simultaneously, the reduction state of the plastoquinone (PQ) pool intensified, the apparent electron transport rate (ETR) increased, and the quantum yield of regulated energy dissipation significantly increased. These adaptations enabled T. ramosissima to dissipate excess light energy by enhancing its non-photochemical energy dissipation mechanisms. (2) Photosynthetically active radiation (PAR) and T. ramosissima leaf temperature (T_L) gradually increased during coppice dune development, whereas soil water content decreased, leading to increased stress on T. ramosissima and a subsequent decline in NSC content. This increased stress placed T. ramosissima at risk of ‘carbon starvation’, resulting in a gradual reduction in photosynthesis, biomass accumulation, and ultimately, mortality. (3) Correlations among various indicators of T. ramosissima were significant, with the highest degree of association and marked enhancement of synergistic effects in the growth and stable stages of coppice dunes. Comprehensive analysis revealed that high soil moisture content can alleviate water stress, improve light energy use efficiency and enhance the photosynthetic carbon assimilation process in T. ramosissima during coppice dune development.

To explore the environmental adaptation mechanisms of Caragana halodendron in leaf traits， to provide a theoretical basis for breeding superior varieties of C. halodendron， and protection of species diversity in desert areas， soil and water conservation， and desertification mitigation， the phenotypic variations among different populations and their relationships with environmental factors were analyzed respectively. The 108 individuals from 18 natural populations of C. halodendron were used as research materials， and 11 leaf-related traits and 28 environmental factors were collected. Pearson correlation analysis and principal component analysis were utilized to explore the variation patterns of leaf traits and their correlations with environmental factors. The results showed that： （1）There were remarkably significant differences in the leaf traits of C.halodendron among different populations. The variation coefficient of leaf traits ranged from 9.42% to 83.12% among the populations and 1.58% to 59.07% intra-populations. Through a detailed comparison of the variation coefficient of traits within and among populations， it was evident that the average coefficient of variation among populations（31.17%） for all traits was higher than that within populations（21.86%）. （2）Correlation analysis of leaf traits revealed significant positive correlation between traits related to leaf shape （leaf length， leaf width， leaf area， specific leaf area）（P<0.05）， and leaf water content showed a significant positive correlation with leaf shape traits（P<0.05）. （3） Four principal components extracted from trait principal component analysis accounted for a cumulative contribution rate of 91.13%. （4）The correlation analysis between leaf traits and environmental factors showed that leaf shape， rachis length， stipular spine length， and the number of leaflets were extremely significantly correlated with multiple environmental factors such as drought， precipitation， temperature， and soil（P<0.01）， whereas specific leaf area was only extremely significantly correlated with multiple environmental factors（P<0.01）. The variation in leaf traits reflects the adaptability of this species to arid and saline-alkali environments and the strategy of C. halodendron adapting to environmental pressure by adjusting traits such as leaf shape， rachis length， and leaf water content. This work provided important insights for understanding the adaptation mechanism of desert plants.

Avena barbata, a wild oat species within the genus Avena, is a widely used model for studying plant ecological adaptation due to its strong environmental adaptability and disease resistance, serving as a valuable genetic resource for oat improvement. Here, we phased the high-quality chromosome-level genome assembly of A. barbata (6.88 Gb, contig N50 = 53.74 Mb) into A (3.57 Gb with 47,687 genes) and B (3.31 Gb with 46,029 genes) subgenomes. Comparative genomics and phylogenomic analyses clarified the evolutionary relationships and trajectories of A, B, C and D subgenomes in Avena. We inferred that the A subgenome donor of A. barbata was Avena hirtula, while the B subgenome donor was probably an extinct diploid species closely related to Avena wiestii. Genome evolution analysis revealed the dynamic transposable element (TE) content and subgenome divergence, as well as extensive structure variations across A, B, C, and D subgenomes in Avena. Population genetic analysis of 211 A. barbata accessions from distinct ecotypes identified several candidate genes related to environmental adaptability and drought resistance. Our study provides a comprehensive genetic resource for exploring the genetic basis underlying the strong environmental adaptability of A. barbata and the molecular identification of important agronomic traits for oat breeding.

The calcineurin B-like protein (CBL)-CBL-interacting protein kinase (CIPK) Ca²⁺ sensors play crucial roles in the plant's response to drought stress. However, there have been few reports on the synergistic regulation of drought stress by CBL-CIPK and abscisic acid (ABA) core signaling components. In this study, we discovered that ZmCIPK33 positively regulates drought resistance in maize. ZmCIPK33 physically interacts with and is enhanced by phosphorylation from ZmSnRK2.10. Drought stress can activate ZmCIPK33, which is partially dependent on ZmSnRK2.10. ZmCIPK33 in combination with ZmSnRK2.10 can activate the slow anion channel ZmSLAC1 in Xenopus laevis oocytes independently of CBLs, whereas ZmCIPK33 or ZmSnRK2.10 alone is unable to do so. Furthermore, ZmCIPK33 phosphorylates ZmPP2C11 at Ser60, which leads to a reduction in the interaction between ZmPP2C11 and ZmEAR1 (the ortholog of Arabidopsis Enhancer of ABA co-Receptor 1) and weakens the phosphatase activity of ZmPP2C11, consequently, enhancing the activity of ZmSnRK2.10 in an in vitro assay and in the in-gel assay of the zmcipk33 mutant. Our findings provide novel insights into the molecular mechanisms underlying the reciprocal enhancement of Ca²⁺ and ABA signaling under drought stress in maize.

The north-south transitional zone in central China is a climatic and ecological sensitive area, and the southern margin of Pinus tabuliformis distribution, yet regional response to climate has not been investigated. Here, we developed different regional chronologies from 14 samplings along an east-west gradient in the Funiu Mountains. Correlation results indicated that regional tree growth was mainly limited by temperature and precipitation in May, especially for YM. Temperature in the south and precipitation in the north were significant limiting effects, except in LCM, where trees were more limited by temperature in the south than precipitation in the north. The limiting effect of temperature in May gradually weakened from east to west, while the effect of precipitation in May was higher in YM (east) and BB (west) than in LCM (middle), and the promoting effect of precipitation in the north was stronger than that in the south. The self-calibrating Palmer Drought Severity Index (scPDSI) had significant positive correlations with tree growth from April to June, with the highest correlation in May. Tree growth increased in the 1970s–80s and then decreased after the 1990s indicated that the growth had degraded under global warming. This result supports the ecological marginal effect theory of growth degeneration of P. tabuliformis in NSTZ under global warming. However, whole regional tree growth also showed stronger recovery and resilience under extreme drought, the resilience basically restored to the pre-disturbance level after three years, which is obviously contradictory with tree growth trend and needs to be further studied.

The physiological response mechanisms of trees to climate change are complex, particularly across varying elevations and among different tree species. In this study, we collected tree ring samples from two dominant conifer species (Picea crassifolia and Pinus tabuliformis) at three elevations at the edge of the Tengger Desert. We used tree-ring width (TRW) and tree ring oxygen isotopes (δ¹⁸O_TR) to investigate how species and elevations affect their responses to climate change. Pearson’s correlation analysis and relative importance analysis were used to study the specific response processes of the two conifers to climate. The results showed that the TRW was mainly controlled by Standardized Precipitation Evapotranspiration Index (SPEI) during the growing season, which means that drought stress had the greatest effect on it. And δ¹⁸O_TR mainly responded to summer relative humidity. Both TRW and δ¹⁸O_TR of P. crassifolia showed higher sensitivity to climate change. This sensitivity is largely attributed to the rapid uptake of precipitation by its developed shallow-rooted root system, which allows it to retain the precipitation signal in both TRW and δ¹⁸O_TR. However, P. crassifolia may be more susceptible to drought stress and growth decline or even death in the context of a warming region. Our results are important for understanding the impacts of climate change on forest ecosystems using multiple indicators and developing corresponding ecological conservation measures.

Drought represents a paramount abiotic stressor constraining global agroforestry productivity. Plants have evolved multifaceted adaptive strategies involving active modulation of symbiotic microbial communities to mitigate drought stress. These plant-associated microbes enhance plant drought adaptation via five principal mechanisms: (i) extracellular polymeric substance-mediated biofilm formation on plant surface enhances hydroregulation and edaphic structural stability; (ii) osmoprotectant biosynthesis (e.g., proline) maintains cellular osmotic equilibrium; (iii) synthesizing antioxidants to reduce damage from reactive oxygen species and oxidative stress; (iv) regulating plant phytohormone metabolism by secreting hormones (e.g. indole-3-acetic acid) and 1-aminocyclopropane-1-carboxylic deaminase; (v) emitting signaling molecules (e.g. volatile organic compounds, hormones and enzymes) to activate plant drought adaptation. Future researches should focus on the development of host-specific drought-adaptive microbial consortia while elucidating phyllosphere–rhizosphere microbiome crosstalk, ultimately harnessing translational microbiome engineering to evaluate their efficacy in multi-environment agricultural systems.

Abstract Aims With climate change, extreme drought events occur frequently around the world, and there is an urgent need to understand the resilience and influencing factors of trees after extreme drought. Methods Seven dominant tree species in karst evergreen and deciduous broad-leaved mixed forest in Guilin, Guangxi were selected to analyze the dynamic differences of xylem water transport function and its correlation with xylem characteristics and environmental factors at the end of extreme drought and after drought. Important findings (1) At the end of extreme drought, the percentage loss of xylem hydraulic conductivity (PLC) of all tree species except Cinnamomum camphora was higher than or close to 50%, and the highest was 87.92%.PLC of all species decreased linearly with the increase of xylem saturation water content at the end of extreme drought. PLC of porous species had significant positive and negative correlations with xylem density (WD) and xylem saturation water content (SWC), respectively, indicating that xylem water storage capacity was an important factor affecting water transport function of karst trees under extreme drought. (2) PLC of Fraxinus chinensis decreased significantly for the first time in the spring of the following year after extreme drought, and the formation of new vessels may be the strategy for restoring water transport function after extreme drought. The PLC of Choerospondias axillaris and Quercus acutissima, Quercus glauca, Boniodendron minius and Machilus calcicola decreased significantly for the first time on the 3rd and 13th day after extreme drought, respectively. The refilling of embolized vessels may be the strategy to restore water transport function of these species. (3) After the extreme drought event, the PLC recovery degree of all tree species at the last 6 sampling times was significantly positively correlated with the mean saturated water vapor pressure deficit (VPD) within 3 days before the current sampling time, indicating that the degree of air dryness had an important effect on the hydraulic function recovery of karst trees after extreme drought after the soil moisture condition recovered. (4) During the recovery process after extreme drought, many tree species showed embolism degree close to or even higher than that at the end of extreme drought, and the embolism fatigue degree of annular porous wood species was higher than that of loose porous wood species.

Aims The accumulation of nutritional components in plants is critically linked to their survival capacity and productivity. Investigating how arbuscular mycorrhizal fungi (AMF) inoculation regulates drought tolerance in plants through nutrient component changes in various organ will establish a theoretical framework for applying AMF to improve crop resilience under water-limited conditions.
Methods The study employed a controlled pot experiment with two water regimes (75% vs. 55% field capacity) and AMF inoculation treatments, using oat (Avena sativa) cultivar ‘Bayou 1’. Mycorrhizal colonization rates were quantified at jointing and filling stages, followed by analysis of non-structural carbohydrates (NSC), carbon (C), nitrogen (N), phosphorus (P) contents in root, stem, and leaf. Grain yield was recorded at the maturity stage.
Important findings In oat plants inoculated with AMF under drought stress, the AMF colonization rate, plant height, and root-to-shoot ratio were significantly enhanced, resulting in 13.31% increase in grain yield. Notably, these improvements in growth parameters and yield exceeded those observed in AMF-inoculated plants under well-watered conditions. Furthermore, AMF inoculation under drought stress increased soluble sugar accumulation in stem and leaf. Concurrently, the contents of C, N, P in root, stem, leaf, as well as the leaf C:N significantly increased, especially the contents of P in leaf. In contrast, the leaf N:P significantly declined. Redundancy analysis revealed that the contents of leaf soluble sugars, and stem C, root N contents served as key indicators explaining variations in growth traits and grain yield under drought stress and AMF inoculation, respectively. Overall, AMF inoculation under drought conditions enhanced oat drought tolerance and hence improved grain yield, primarily attributed to increase AMF colonization rate, which facilitated synergistically the accumulation of soluble sugar and C, N, P in organs, and modulated the leaf stoichiometric ratios (C:N and N:P).

The karst forest in southwestern China is characterized by thin soil layers, numerous fissures and holes, resulting in low soil water availability and poor water retention, making it challenging for plant growth and survival. While the relationship between plant functional traits and tree growth performance has been extensively studied, the links between tree seasonal growth and drought-tolerant traits in tree species with different leaf habit remains poorly understood. This study evaluated the associations between four-year averaged rainy season stem diameter growth rate and 17 branch and leaf traits across evergreen and deciduous species in a tropical karst forest in southwest China. The cross-species variations in tree growth rates were related to plant hydraulic traits (e.g., vessel lumen diameter, xylem vessel density, stomatal density, and stomatal size) and leaf anatomical traits (e.g., total leaf thickness, lower/upper epidermis thickness, and spongy thickness). The growth of evergreen trees exhibited lower hydraulic efficiency but greater drought tolerance than deciduous tree, which enabled them to maintain higher persistence under low soil water availability and consequently a relatively longer growing season. In contrast, deciduous species showed no correlation between their functional traits and growth rate. The distinct water use strategies of evergreen and deciduous trees may offer a potential explanation for their co-existence in the tropical karst forests.

The mechanisms of plant adaptation to environmental gradients have been the focus of ecological research, with environmental stresses driving coordinated or differentiated regulation of plant functional traits. Plant resource acquisition involves root trait plasticity and mycorrhizal symbiosis. However, root trait plasticity along precipitation gradients and root-mycorrhizal trade-offs remain unclear. We conducted community surveys along a west-east precipitation gradient in four natural grassland communities (alpine desert steppe, alpine steppe, alpine meadow steppe and alpine meadow) on the plateau in northern Xizang Plateau. Six key root traits (root diameter, RD; root dry matter content, RDMC; root tissue density, RTD; specific root length, SRL; root branching intensity, RBI; and root length colonization percentage, RLC) were measured in 18 alpine plant species to investigate the coordination and trade-offs between root traits and mycorrhizal fungi along the precipitation gradient. Our results showed community-level declines in RDMC, RD, RTD and RLC with increasing precipitation, contrasting with elevated RBI and SRL. Functional groups exhibited distinct patterns: grasses and legumes demonstrated root-mycorrhizal trade-offs, sedges displayed synergy and forbs showed inconsistent responses. Divergent trends in plant root traits and mycorrhizal fungi were observed at the species level. Alpine plants in humid eastern meadows favored root elongation, while those in arid western desert steppe relied on radial growth and mycorrhizal fungal cooperation for resource acquisition. These findings highlight varied root absorption strategies among alpine plants along environmental gradients, supporting the importance of ecological niche diversification in maintaining alpine ecosystem diversity and stability.