Scanning electron microscopy (SEM) was used to conduct morphological observations on diatoms of the genera Falcula and Pseudofalcula distributed along the coasts of South China and Australia. Falcula media Voigt was reported as a newly recorded diatom species for China, while the ultrastructural morphology of F. semiundulata Voigt was studied for the first time. Morphological differences between Falcula and Pseudofalcula were further defined by comparing the former two species with P. hyalina (Takano) Gomez, Wang, & Lin. A key distinguishing feature between the two genera was the structure of the apical pore fields, comprising several slits in Falcula, and presenting as an ocellulimbus with a grid-like structure set into the valve mantle in Pseudofalcula. Falcula species were mainly epiphytic diatoms attached to seaweeds, while Pseudofalcula species were typically epizoic and attached to marine copepods. This study expands the geographic distribution of F. media, F. semiundulata, and P. hyalina and clarifies the basis of the morphological classification of the Falcula and Pseudofalcula genera.
Gastrodia putaoensis X. H. Jin is reported here as a newly recorded species for China, located in Motuo, Xizang. Originally discovered in northern Myanmar, this species was first described in 2017. Distinct from all other species within the genus, G. putaoensis is characterized by a bifurcated lip, comprising two segments. The apical part is densely covered with yellow hairs, while the apex of the part is densely covered with red papillae. This revised account expands upon the initial description by providing enhanced morphological details and including photographs of the floral anatomy, serving as supplementary data for the species G. putaoensis.
Armeniaca hongpingensis T. T. Yu & C. L. Li is a critically endangered species distributed only in Hongping Town, Shennongjia, Hubei Province, China. According to the Flora of China, A. hongpingensis and A. mume var. bungo Makino may be natural hybrids of A. mume Lam. and A. vulgaris Siebold. To date, however, no morphological study on the relationship between A. hongpingensis, A. vulgaris, A. mume, and A. mume var. bungo has been conducted. Through field investigations, 21 quantitative and 15 qualitative leaf, flower, fruit, kernel, and branch characters were obtained, followed by cluster analysis. Results showed that both PAM and UPGMA cluster analysis clearly divided the specimens into four species, indicating obvious distinguishing characters among them. Based on principal component analysis, the absolute weight values of annual branch color and hair-covering status, hair-covering status of leaf and fruit, leaf shape index (leaf shape, leaf tip, leaf base), and surface characters of kernel in the first three principal components were all above 0.9, indicating that these traits play important roles in the classification of the four Armeniaca species. Based on electron microscopy, the pollen grains were identified as single grain (monads), isopolar, radially symmetrical, and tri-colporate. The pollen surfaces of A. vulgaris, A. mume, and A. mume var. bungo were striate-ornamented, while the pollen of A. hongpingensis was discontinuously striped and showed inconspicuous perforation. The epidermal cells of the leaves of the four plants all showed striate keratinization. Compared to the other species, the stripes on the cell surface of A. hongpingensis were often curved, overlapped, and without fixed direction. According to cluster analysis and micromorphological characters, A. hongpingensis should be treated as an independent species from A. vulgaris and A. mume.
To study the effects of intercropping with forage grasses on the composition and diversity of weed communities in an apple orchard in Nyingchi, Tibet, two annual grasses (Avena sativa L. and Vicia sativa L.) and two perennial grasses (Medicago sativa L. and Dactylis glomerata L.) were single sown or mixed sown, with grasses naturally growing after clear tillage used as a control. The weed communities were then surveyed in 2011 and 2022, respectively. A total of 33 weed species belonging to 31 genera and 17 families were found in the experimental plots in the two studied years. The dominant families were Gramineae, Leguminosae, Polygonaceae, and Asteraceae, and the dominant species were Pennisetum flaccidum Griseb., Eragrostis pilosa (L.) Beauv., Galinsoga parviflora Cav., Taraxacum mongolicum Hand.-Mazz., and Persicaria microcephala (D. Don) H. Gross. Intercropping with forage grasses led to a reduction in weed species richness and importance values of the dominant weed species, which were influenced by forage grass species and planting year. Intercropping also resulted in lower species diversity of the weed communities, with both planting year and cropping pattern significantly affecting community diversity and dominance. Weed control efficacy was higher for Gramineae forage compared to Leguminosae forage, and mixed sowing showed better results than single sowing treatment. The above findings suggest that the selection of forage grasses should be based on their growth period, with annual forages being more effective for short-term weed control and perennial forages being more suitable for long-term grass planting in orchards.
Arbuscular mycorrhizal fungi (AMF) play a vital role in maintaining the functionality and stability of plateau wetland ecosystems. However, the diversity of AMF communities along elevational gradients and their response to construction processes in the South-Tibet River Basin remain unclear. In this study, we conducted a wetland plant community survey, measured the physicochemical properties of water in situ, and collected sediment samples for further analysis across a high elevational gradient (4 200 to 5 100 m) in the South-Tibet River Basin. Results revealed that Glomus was the dominant genus within the Qinghai-Tibet Plateau wetland ecosystem. However, its relative abundance varied greatly with elevation, showing a significant declining trend with increasing elevation. Differences in AMF community composition were primarily due to species replacement. Variance partitioning analysis showed that the contribution of environmental variables to the AMF diversity-elevation patterns mainly involved sediment and water factors, with a lesser contribution from plant factors. These findings suggest that the establishment of the AMF community in the wetland habitat of the South-Tibet River Basin is predominantly governed by deterministic processes at high elevational gradients, reflecting a unique model of AMF community construction in the Qinghai-Tibet Plateau. However, further validation of these results is warranted.
This study presents comprehensive data on the geographical distribution of the genus Pyrola across China, gathered through extensive literature review and specimen analysis. Results showed that: (1) Pyrola is ubiquitously distributed throughout all Chinese provinces, with Jilin and Sichuan recording the highest species counts, each hosting 10 species. (2) The Pyrola genus exhibits a predominant north temperate distribution type, but at the species level, the Chinese endemic distribution type is most common. (3) The altitudinal range of Pyrola spans from sea level to 4 100 m, primarily between 1 500–2 500 m. (4) There is a significant overlap between Pyrola distribution areas and coniferous forests in China, predominantly within boreal coniferous forests, indicating their significance for vegetation restoration.
Valine-glutamine (VQ) is a plant-specific protein, which plays an important role in plant growth, development, and resistance to biotic and abiotic stresses. To date, however, little research has been conducted on the VQ gene family in perennial ryegrass (Lolium perenne L.). In this study, 52 LpVQ genes were identified in the perennial ryegrass genome, which were unevenly distributed on seven chromosomes. Subcellular localization prediction indicated that LpVQ proteins were mainly located in the nucleus, with only LpVQ45 located in the cell membrane. Phylogenetic analysis showed that LpVQ genes were divided into seven subfamilies and there were only four pairs of lineal homologous genes with Arabidopsis. Based on gene structure analysis of the LpVQ gene family, 88.46% of LpVQ genes had no intron. Finally, three LpVQ genes were randomly from each subfamily to observe the responses to dark, high temperature, and salt stress. The qRT-PCR analysis LpVQ genes responded quickly in early stages of stress. This study provides a theoretical foundation for further study on VQ family genes of perennial ryegrass under abiotic stress.
Gymnosphaera podophylla Dalla Torre & Sarnth. is a famous relict tree fern with strong environmental adaptability. However, the mechanisms underlying its adaptability remain unclear. In this study, the PacBio and Illumina platforms were used to sequence the root, rachis, and pinna transcriptomes of G. podophylla, resulting in the generation of 12 879, 14 185, and 16 084 full-length unigenes, respectively. Transcript quantification showed that these unigenes were related to drought resistance and biological stress and were highly expressed. KEGG enrichment analysis indicated that the up-regulated genes in the roots, rachis, and pinna were enriched in the "phenylpropane biosynthesis pathway", while the up-regulated genes in the roots and rachis were enriched in the "flavonoid biosynthetic pathway". A total of 192 full-length unigenes were annotated as structural genes involving 13 enzymes in the flavonoid biosynthesis pathway, including 112 differentially expressed genes (DEGs), suggesting that the flavonoid biosynthesis pathway was conserved in G. podophylla, with organ-specific DEGs. This research is the first to perform a comprehensive analysis of the full-length transcriptome across multiple organs in G. podophylla and to investigate the structural genes of the flavonoid biosynthetic pathway. This study provides an abundance of genetic resources for further examination of environmental adaptation in this species.
Hypocotyl elongation is essential for early survival and later growth and development in plants. In this investigation, we examined and screened Arabidopsis thaliana (L.) Heynh. mutant phenotypes, identifying the u2bl variant with a notable short hypocotyl. We also conducted preliminary studies on the role of U2BL in the regulation of hypocotyl development in A. thaliana. The u2bl mutant showed a short hypocotyl phenotype under different light conditions. Cytological experiments showed the shorter cell length of hypocotyls in the u2bl mutant was the reason for its short hypocotyl phenotype. The plant hormone gibberellin (GAs) is the main factor promoting hypocotyl elongation, while paclobutrazol (PAC) is an endogenous GA synthesis inhibitor. Our study showed that the u2bl mutant was not sensitive to exogenous GA treatment or PAC treatment, indicating that U2BL affected GA signal transduction. Subcellular localization results indicated that U2BL was enriched in the nucleus. Furthermore, Q-PCR assay showed that the transcription levels of PRE1, SAUR16, YUC2, YUC8, and PIF4 genes were all significantly down-regulated in the u2bl mutant, suggesting that U2BL may indirectly regulate hypocotyl elongation by regulating the above genes. Our study provided a reference for further research on the possible functions of U2BL in the growth and development of A. thaliana and other species.
In this study, 10 foxtail millet (Setaria italica L.) germplasm accessions were treated with varying concentrations of NaCl solution. By analyzing four indexes, including the relative germination potential, relative germination rate, relative shoot length, and relative root length during germination stage, we established that the suitable NaCl concentration for the identification of salt tolerance during germination in foxtail millet was 180 mmol/L. To evaluate the salt-tolerance of 180 core germplasms during the germination stage, correlation analysis and principal component analysis were employed to calculate the aforementioned four traits under 180 mmol/L NaCl treatment. Comprehensive evaluation and salt-tolerant grade of the 180 germplasms were identified by membership functional analysis and cluster analysis. Results revealed that except for the non-significant correlation between relative germination rate and relative shoot length, all other indexes showed a highly significant positive correlation. Furthermore, principal component analysis suggested that the four indexes could be considered as key indices for assessing salt tolerance. Cluster analysis revealed that the 180 germplasms could be divided into four groups: highly salt tolerant, salt tolerant, salt sensitive, and extremely salt sensitive. Jiangu, Henggu 12, Qitoubai, K-3606, and Jingu 20 were identified as extremely salt tolerant accessions through comprehensive evaluation using membership function. In addition, under 180 mmol/L NaCl stress, 40 lines from the F7 generation recombinant inbred line (RIL) of Heizhigu (extremely salt-sensitive)×Changnong 35 (salt-tolerant) were analyzed. Results showed significant variation among the 40 lines, with their frequency distribution of salt tolerance grades approximating normal distribution, indicating that this population was suitable for salt-tolerant QTL mapping. These findings demonstrated that 180 mmol/L NaCl could be used for the identification of salt-tolerant foxtail millet germplasms during the germination stage and that at this concentration, salt tolerance differences among various germplasms can be better distinguished by four indexes: relative germination potential, relative germination rate, relative shoot length, and relative root length.
Gardenia jasminoides J. Ellis flowers are white in color and have a pleasant aroma. These flowers have high ornamental value and are an important source of natural spices. Terpenes are the main components of the unique aroma of G. jasminoides flowers, but the key terpene synthases (TPSs) for the biosynthesis of such volatile products have not yet been identified. Here, based on the high-quality genome of G. jasminoides, this study comprehensively explored the TPS genes related to floral scent biosynthesis through transcriptomic, phylogenetic, and conserved domain analysis. In total, 44 GjTPS genes were identified in G. jasminoides, unevenly distributed on 11 chromosomes, and nine GjTPS genes participated in tandem duplication events. All GjTPSs were clustered into five subfamilies, 27 of which belonged to the angiosperm-specific clades, including TPS-a, TPS-b, and TPS-g. Combining transcriptomic data and quantitative real-time PCR (qRT-PCR) analyses of five organs, five candidate GjTPS genes, with high expression in blooming flowers and containing the active motif DDXXD and NSE/DTE, were screened. Among them, GjTPS1, GjTPS2, GjTPS3, and GjTPS27 were grouped in the TPS-b clade, speculated to be the TPSs responsible for the biosynthesis of the main floral aroma components of G. jasminoides, such as linalool and ocimene, while GjTPS18 from the TPS-a clade may be a farnesene synthase.
The composition, content, and structure of anthocyanins and flavonoids in purple-red, pink, and white petals of Bauhinia variegata L. were studied to lay a foundation for further investigations of the floral pigment mechanisms and molecular breeding of this species. The anthocyanins and flavonoids were analyzed using liquid chromatography-mass spectrometry (LC-MS/MS). In total, 53 anthocyanins and 340 flavonoids were detected. However, the anthocyanins were markedly different among the different colored petals. Malvidin-3-O-galactoside, malvidin-3-O-glucoside, delphinidin-3-O-galactoside were higher in the purple-red petals than in the white and pink petals. Delphinidin-3-O-(coumaryl)-glucoside, malvidin-3-O-sophoroside, petunidin-3-O-(coumaryl)-glucoside were higher in the pink petals than in the purple-red and white petals. Pelargonidin-3-O-(coumaryl)-glucoside was higher in the white petals than in the purple-red and pink petals. The flavonoids also differed significantly among the different petals. Pelargonidin-3-O-sambubioside-5-O-glucoside, pelargonidin-3-O-sophoroside, and delphinidin-3-O-sambubioside were almost not detected in the white petals and delphinidin-3-O-sophoroside was almost not detected in the purple-red petals, while peonidin-3-O-glucoside, peonidin-3,5-O-diglucoside, chrysoeriol-7-O-rutinoside-5-O-glucoside, and isovitexin-7-O-(6''-sinapoyl) glucoside were higher in the pink than in the white and purple-red petals.
The successful invasion of alien plants is regulated by both abiotic factors (such as changes in aboveground and underground resources) and biological factors (such as mutualistic symbionts). In this study, the typical invasive plant Trifolium repens L. was used to investigate the effects of light, phosphorus, symbiotic arbuscular mycorrhizal fungi (AMF), and their interactions on growth using a three-factor two-level orthogonal experiment. Results showed that: (1) High light, high phosphorus, and AMF inoculation significantlyincreased the biomass and growth rate of T. repens. The promotion effect of AMF inoculation on biomass increased with increasing light, and the promotion effect of AMF on total biomass and relative growth rate was more pronounced under low phosphorus conditions; (2) High light intensity reduced specific leaf area but improved the performance of other aboveground traits, except for root mass fraction. High phosphorus and AMF inoculation significantly increased the number of leaves and total leaf area, which was more obvious under high light intensity; (3) High light intensity significantly increased root surface area, root diameter, and root mass fraction, but decreased the proportion of fine roots and specific root length. The promotion effect of high light intensity on root surface area was higher under low phosphorus. High phosphorus significantly reduced the root mass fraction. In the absence of AMF inoculation, high phosphorus increased the root surface area and root diameter and decreased the proportion of fine root length. However, after inoculation with AMF, high phosphorus reduced the root surface area and root diameter and also increased the proportion of fine root length. AMF significantly reduced the root mass fraction and specific root length. Overall, these results showed that light, phosphorus, and AMF significantly affected T. repens growth, and the intensity of the effects of phosphorus and AMF on growth and aboveground traits was dependent on light intensity, while the intensity of the effects of AMF on underground traits was dependent on phosphorus concentration.
In this study, different concentrations of Phoebe bournei(Hemsl.) Yang litter branch and leaf extracts were tested to treat P. bournei seeds and seedlings. Seed germination, seedling growth, and physiological indices were measured. Results showed that: (1) Extracts of P. bournei litter branches and leaves inhibited seed germination at all concentrations. Inhibition intensity was enhanced with the increase in the concentration of the two extracts. However, inhibition intensity of the litter branches was greater than that of the litter leaves. Notably, inhibition intensity was branch>leaf regarding the germination index; leaf>branch regarding root bud length; and branch>leaf regarding comprehensive allelopathy. (2) Litter branch extracts inhibited the growth of one-year-old P. bournei seedlings, while litter leaf extracts showed “low promoting and high inhibiting” effects. High concentrations of the extracts seriously inhibited the growth of seedlings, causing many leaves to develop spots, atrophy, and yellow color. (3) The effects of litter extracts on P. bournei seedling physiology were complex. High-concentration extracts disturbed the physiological of seedlings, causing abnormalities in the antioxidant system, significant increases in malondialdehyde (MDA) content, and increases in cell membrane permeability in leaves, resulting in an abnormal growth state. Long-term exposure to low-concentration extracts induced stress in the plants and caused changes in related physiological indices.
The abscission of fruit is a crucial stage in the ontogeny of fruit trees, signifying the detachment of fruit from the tree body. This process is integral to the survival, growth, reproduction, and economic value of fruit trees. As such, analyzing the molecular mechanisms that regulate fruit abscission is important for improving fruit tree varieties and fruit quality. Fruit abscission predominantly occurs in the abscission zone, a region in which the generation and reception of abscission-stimulating signals are regulated by multiple genes. This regulatory process is the outcome of the joint action of various factors, including cellular structure, carbohydrates, cell wall metabolic enzymes, ethylene synthesis, and signal transduction pathways. The functional dynamics and interrelationships of these factors warrant further exploration. In light of this, the present paper provides a comprehensive review of the formation and structural changes of the abscission zone, concentrations of carbohydrates, ethylene, and other substances, and expression of related genes during the fruit abscission process in fruit trees. This review aims to provide novel insights into the study of the fruit abscission mechanism and to lay a theoretical foundation for the scientific regulation of fruit abscission, improvement of fruit quality, and reduction of losses in fruit tree production.
