A limnological study was carried out to determine the responses of superoxide dismutase (SOD) activities and soluble protein (SP) contents of 11 common aquatic plants to eutrophication stress. Field investigation in 12 lakes in the middle and lower reaches of the Yangtze River was carried out from March to September 2004. Our results indicated that nonsubmersed (emergent and floating-leafed) plants and submersed plants showed different responses to eutrophication stress. Both SOD activities of the non-submersed and submersed plants were negatively correlated with their SP contents (P < 0.000 1). SP contents of non-submersed plants were significantly correlated with all nitrogen variables in the water (P < 0.05), whereas SP contents of submersed plants were only significantly correlated with carbon variables as well as ammonium and Secchi depth (SD) in water (P < 0.05). Only SOD activities of submersed plants were decreased with decline of SD in water (P < 0.001). Our results indicate that the decline of SOD activities of submersed plants were mainly caused by light limitation, this showed a coincidence with the decline of macrophytes in eutrophic lakes, which might imply that the antioxidant system of the submersed plants were impaired under eutrophication stress.

Wu AP, Cao T, Wu SK, Ni LY, Xie P (2009) Trends of superoxide dismutase and soluble protein of aquatic plants in lakes of different trophic levels in the middle and lower reaches of the Yangtze River, China. J. Integr. Plant Biol. 51(4), 414–422.

The aim of the present study is to probe the relation between plant growth and its decontamination effect in constructed wetlands. Four species were studied in the small-scale mono-cultured constructed wetlands, which were fed with domestic wastewater. Plant rowth indexes were correlated with contaminant removal performance of the constructed wetlands. Wetlands planted with Cyperus flabelliformis Rottb. showed the highest growth indexes such as shoot growth, biomass, root activity, root biomass increment, and the highest contaminant removal rates, whereas wetlands planted with Vetiveria zizanioides L. Nash had the lowest growth indexes and the lowest removal rates. Above-ground biomass and total biomass were significantly correlated with ammonia nitrogen removal, and below-ground biomass with soluble reactive phosphorus removal. Photosynthetic rate had higher correlation with nitrogen removal in these species. Root activity and root biomass increment was more correlated with 5 d biochemical oxygen demand removal. Chemical oxygen demand removal had lower correlations with plant growth indexes. All four species had higher removal rates in summer and autumn. The results suggest that the effect of plant growth on contaminant removal in constructed wetlands were different specifically in plants and contaminants. 

Cheng XY, Liang MQ, Chen WY, Liu XC, Chen ZH (2009). Growth and contaminant removal effect of several plants in constructed wetlands. J. Integr. Plant Biol. 51(3), 325–335.

Responses of the photosynthetic activity of Phaeodactylum tricornutum (Bacillariophyta) to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic conditions. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic conditions, but was decreased under photoheterotrophic conditions. In comparison with photoautotrophic conditions, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of photosystem (PS) I and PS II and the values of F685/F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There was a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS II. These results suggested that the PS II activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity. 

Liu XJ, Duan SS, Li AF, Sun KF (2009). Effects of glycerol on the fluorescence spectra and chloroplast ultrastructure of Phaeodactylum tricornutum (Bacillariophyta). J. Integr. Plant Biol. 51(3), 272–278.

Aquatic plants develop strong fragment propagation and colonization ability to endure the natural disturbances. However, detailed research of ability to endure the natural disturbances has been lacking to date. Therefore, reproduction (shoot) and colonization (root) of shoot fragments of Potamogeton crispus L. with or without apices were investigated for the effect of apical dominance, and the growth of decapitated shoot fragments at three lengths (2, 4, 6 cm) was compared. Meanwhile, fragment propagation at levels of bud position was studied for bud position effect after escaping from apical dominance. The results showed significant increases occurred in the outgrowth of lateral branches on fragments decapitated compared with the fragments with apices, implying that apical dominance exists. Different lengths of fragments showed little difference in biomass allocations, but significant differences were noted in their propagation. Meanwhile, the effect of bud position was verified, due to the significant difference of average reproduction per node among the three length groups. Thus, the present study has made progress in the current understanding of aquatic plant dispersion among natural systems and contributes to improve methods of in vitro propagation for re-implantation purposes. 

Jiang J, An S, Zhou C, Guan B, Sun Z, Cai Y, Liu F (2009). Fragment propagation and colonization ability enhanced and varied at node level after escaping from apical dominance in submerged macrophytes. J. Integr. Plant Biol. 51(3), 308–315.

Soil hosts diverse communities of photosynthetic eukaryotes (algae) that have not yet been fully explored. Here we describe an interesting coccoid green alga isolated from a soil sample from a forest-steppe in South Urals (Bashkortostan, Russia) that, based on a phylogenetic analysis of 18S rRNA gene sequence, appears to represent a new phylogenetic lineage related to the genus Leptosira within the class Trebouxiophyceae. This new alga is characterized by uninucleate cells with a shape ranging from spherical to ellipsoid or egg-like, occurring solitary or more often grouped in irregular masses or colonies. Remarkably, cells with a characteristic pyriform shape are encountered in cultures grown on a solid medium. The cells harbour a single pyrenoid-lacking parietal chloroplast with the margin undulated or forming finger-like projections; in mature cells the chloroplast becomes divided by deep incisions into more or less separate lobes. Transmission electron microscopy of vegetative cells revealed an unprecedented structure in the form of a cluster of microfibrils located in the cytoplasm near the plasma membrane, often appressed to the chloroplast. Reproduction takes place via autospores or biflagellated zoospores. The unique suite of characters of our isolate distinguishes it from previously described coccoid green algae and suggests that it should be classified as a new species in a new genus; we propose it be named Chloropyrula uraliensis.

We have identified hpm91, a Chlamydomonas mutant lacking Proton Gradient Regulation5 (PGR5) capable of producing hydrogen (H₂) for 25 days with more than 30-fold yield increase compared to wild type. Thus, hpm91 displays a higher capacity of H₂ production than a previously characterized pgr5 mutant. Physiological and biochemical characterization of hpm91 reveal that the prolonged H₂ production is due to enhanced stability of PSII, which correlates with increased reactive oxygen species (ROS) scavenging capacity during sulfur deprivation. This anti-ROS response appears to protect the photosynthetic electron transport chain from photo-oxidative damage and thereby ensures electron supply to the hydrogenase.

Filamentous cyanobacterium (strain 10C-PS) isolated from a fresh water body of Bilaspur, Chhattisgarh, India is being described as new species of the polyphyletic genus Scytonema. Phenotypic, molecular and phylogenetic characterization was performed and the combined results validated the strain as a new species. Careful observations of the filaments, presence of a distinctly textured sheath throughout the length of the trichome, differences in the shape and dimensions of the vegetative cells, and heterocytes provided reliable morphological signals that the strain differed from rest of the closely related species. Sequencing of the 16S rRNA gene showed 96.89% sequence similarity with Scytonema hofmanni PCC 7110 while rbcl and psbA sequencing showed 95% and 92% similarities with Scytonema hofmanni PCC 7110 and Nostoc sp. PCC 7524 respectively while the nifD gene sequence similarity was found to be 96% with Scytonema hofmanni PCC 7110. The PC-IGS region was sequenced and concatenated cpcB, IGS and cpcA regions indicated 97% closest similarity with Scytonema sp. PCC 7110 and Scytonema bohnerii Ind24. Subsequent phylogenetic analyses gave a strong pattern of distinct clustering in case of all the molecular markers. The phenotypic, genetic and phylogenetic observations prove conclusively that the strain 10C-PS is a new species in the genus Scytonema with the name proposed being Scytonema bilaspurensis.

Green plants comprise two main clades: the Streptophyta, which include charophyte green algae and the embryophytic land plants, and the Chlorophyta including a wide diversity of marine, freshwater, and terrestrial green algae. Establishing a robust phylogeny is important to provide an evolutionary framework for comparative and functional studies. During the last two decades our understanding of the evolution of green algae has profoundly changed, first by phylogenetic analyses of nuclear ribosomal sequence data (mainly 18S), and more recently by analyses of multi-gene and chloroplast genomic data. The phylogenetic relationships among the main streptophytan lineages have been extensively studied and are now relatively well resolved. Although a lot of progress has been made in the last few years, the phylogenetic relationships in the Chlorophyta are still less well established. Here we review how chloroplast genomic data have contributed to address relationships among the main chlorophytan lineages. We highlight recent progress and conflicts among different studies, and discuss future directions in chloroplast phylogenomics of green algae.

The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models (LSM). Particularly in high-altitude regions, choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM simulations. Therefore, this study conducted four offline LSM simulations over the Tibetan Plateau (TP) using the Community Land Model version 4.5 (CLM4.5) driven by four state-of-the-art atmospheric forcing datasets. The performances of CRUNCEP (CLM4.5 model default) and three other reanalysis-based atmospheric forcing datasets (i.e. ITPCAS, GSWP3 and WFDEI) in simulating the net primary productivity (NPP) and actual evapotranspiration (ET) were evaluated based on in situ and gridded reference datasets. Compared with in situ observations, simulated results exhibited determination coefficients (R²) ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET, respectively, among which GSWP3 and ITPCAS showed superior performance. At the plateau level, CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ET. GSWP3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and ET. The simulated ET increase over the TP during 1982–2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET, suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the TP. These results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the TP. This study contributes to enhancing the accuracy of LSM in water–carbon simulations over alpine regions.

Pan evaporation (E_pan) is a critical measure of the atmospheric evaporation demand. Analyzing meteorological data from the Tropical Rainforest Comprehensive Meteorological Observation Field in the Xishuangbanna Tropical Botanical Garden (XTBG Meteorological Observing Station) based on physical models is helpful to improve our understanding of the state of the hydrological cycle in the Xishuangbanna tropical rainforest region. In this study, we investigated the long-term trend in E_pan using the observation data from 1959 to 2021. Moreover, correlation analyses of E_pan were performed, such as trend test, assessment of periodic properties and abrupt change analysis. Then, D20 E_pan data and related meteorological data from 1979 to 2008 were used to drive Penman‒Monteith and PenPan models for simulating E_pan. The partial derivative attribution method was used to analyze the dominant factors affecting E_pan. The results showed that E_pan exhibits obvious periodic changes, the 19a is the first primary period. In addition, there was a clear ‘evaporation paradox’ phenomenon in Xishuangbanna. E_pan showed a decreasing trend during both 1959-2008 and 2009-2018, and the decreasing trend reached a significant level with a rate of -3.404 mm·a^-2 during 1959-2008. Through comparative analysis, the PenPan model was considered more suitable for simulating E_pan in Xishuangbanna. In order to identify the main meteorological factors influencing E_pan, complete data from the D20 pan monitoring period, namely, 1979-2008, were selected for attribution calculations. The variations in the net radiation and saturated vapor pressure deficit are the main triggers that explain the ‘evaporation paradox’ phenomenon in Xishuangbanna.

Energy partitioning and evapotranspiration (ET) of alpine meadows in permafrost areas are crucial for water cycle on the Qinghai-Tibet Plateau. However, seasonal (freeze-thaw cycle) variations in energy partitioning and ET and their driving factors must be clarified. Therefore, 4-year energy fluxes [i.e. latent heat (LE) and sensible heat (H)] were observed, and bulk parameters [i.e. surface conductance, decoupling coefficient (Ω), and Priestley-Taylor coefficient (α)] were estimated in an alpine meadow in the Qinghai-Tibet Plateau. Mean daily LE (27.45 ± 23.89 W/m²) and H (32.51 ± 16.72 W/m²) accounted for 31.71% and 50.14% of available energy, respectively. More available energy was allocated to LE during the rainfall period, while 67.54 ± 28.44% was allocated to H during the frozen period. H was half the LE during rainfall period and seven times the LE during frozen period due to low soil water content and vegetation coverage during the frozen season. Mean annual ET was 347.34 ± 8.39 mm/year, close to mean annual precipitation. Low mean daily Ω (0.45 ± 0.23) and α (0.60 ± 0.29) throughout the year suggested that ET in the alpine meadow was limited by water availability. However, ET was constrained by available energy because of sufficient water supply from precipitation during rainfall season. In contrast, large differences between ET and precipitation indicated that soil water was supplied via lateral flow from melting upstream glaciers and snow during the transition season. The results suggest that seasonal variations in bulk parameters should be considered when simulating water and energy fluxes in permafrost regions.

Direct sewage discharge may enhance soil nitrous oxide (N₂O) emissions, worsening the greenhouse effect. However, the effects of sewage discharge into bogs on N₂O flux, drivers and influencing mechanisms remain unclear. Additionally, investigating the impact of reclaimed water on N₂O flux is important for bog replenishment and water shortage alleviation. This study simulated sewage from different sources into a bog and analyzed N₂O fluxes, soil (organic carbon, total nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorus, available phosphorus, pH and electrical conductivity), plant (species richness and biomass) and microorganisms (ammonia-oxidizing archaea, napA, nirS, nirK and nosZ genes). Results showed that the reclaimed water did not significantly change N₂O flux, while 50% tap water mixed with 50% domestic sewage and domestic sewage significantly increased the N₂O flux. Among soil factors, available nitrogen and pH were key in influencing N₂O flux. Among plant parameters, species richness was the primary factor affecting N₂O flux. Nitrogen transformation functional genes contributed the most to the increase in the N₂O fluxes, with an increase in domestic sewage input leading to a higher abundance of these genes and subsequent N₂O emissions. Therefore, domestic sewage should be considered, as it significantly increases N₂O emissions by affecting the soil, plants and microorganisms, thereby increasing the global warming potential. This study’s findings suggest that using treated reclaimed water for bog replenishment could be an environmentally friendly approach to wetland management.

Algal blooms significantly affect microbial communities in wetland ecosystems. However, little is known about the succession of sediment microbial communities during algal blooms. This study aimed to investigate the temporal patterns of sediment bacterial community structure and function succession during algal blooms (March to May 2022) with high-throughput sequencing technology. To this end, algal blooms were divided into the bloom stage (BS), decomposition stage (DS) and end stage (ES). The results showed that: (i) The algal blooms were dominated by Microcystis species within Cyanobacteria. Both phytoplankton abundance and biomass reached the peak in the BS, with 45.78 × 10⁵ cells/L and 5.97 mg/L, respectively. (ii) The alpha diversity indices of the sediment bacterial community showed a monotonically increasing trend, with the lowest value in the BS. Cyanobacterial blooms reduced the relative abundance of Actinobacteria and Chloroflexi, and raised that of Firmicutes, Proteobacteria and Bacteroidetes. (iii) Cyanobacterial blooms remarkably decreased the complexity of the co-occurrence network of the sediment bacterial community, which resisted extreme environmental conditions in the BS and DS by increasing positive relationships. (iv) Mantel test showed that phytoplankton biomass, T, dissolved oxygen and organic carbon had significant effects on the sediment bacterial community. The results of this study are important for the ecological management of algal blooms through microorganisms.