of Botany,Chinese Academy Of Sciences
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Compensatory growth as a response to post-drought in grassland
No full textGrasslands are structurally and functionally controlled by water availability. Ongoing global change is threatening the sustainability of grassland ecosystems through chronic alterations in climate patterns and resource availability, as well as by the increasing frequency and intensity of anthropogenic perturbations. Compared with many studies on how grassland ecosystems respond during drought, there are far fewer studies focused on grassland dynamics after drought. Compensatory growth, as the ability of plants to offset the adverse effects of environmental or anthropogenic perturbations, is a common phenomenon in grassland. However, compensatory growth induced by drought and its underlying mechanism across grasslands remains not clear. In this review, we provide examples of analogous compensatory growth from different grassland types across drought characteristics (intensity, timing, and duration) and explain the effect of resource availability on compensatory growth and their underlying mechanisms. Based on our review of the literature, a hypothetic framework for integrating plant, root, and microbial responses is also proposed to increase our understanding of compensatory growth after drought. This research will advance our understanding of the mechanisms of grassland ecosystem functioning in response to climate change
High-temperature adaptation of an OsNRT2.3 allele is thermoregulated by small RNAs
No full textClimate change negatively affects crop yield, which hinders efforts to reach agricultural sustainability and food security. Here, we show that a previously unidentified allele of the nitrate transporter gene OsNRT2.3 is required to maintain high yield and high nitrogen use efficiency under high temperatures. We demonstrate that this tolerance to high temperatures in rice accessions harboring the HTNE-2 (high temperature resistant and nitrogen efficient-2) alleles from enhanced translation of the OsNRT2.3b mRNA isoform and the decreased abundance of a unique small RNA ( sNRT2.3-1) derived from the 5' untranslated region of OsNRT2.3. sNRT2.3-1 binds to the OsNRT2.3a mRNA in a temperature-dependent manner. Our findings reveal that allelic variation in the 5' untranslated region of OsNRT2.3 leads to an increase in OsNRT2.3b protein levels and higher yield during high-temperature stress. Our results also provide a breeding strategy to produce rice varieties with higher grain yield and lower N fertilizer input suitable for a sustainable agriculture that is resilient against climate change
Subtropical forest vegetation development and climate change in Baishanzu area of Zhejiang Province, China, since the Holocene
No full textHuman activities and climate change pose major challenges for the sustainable development of terrestrial biological forests. The modern vegetation in the Baishanzu area is typical mixed subtropical evergreen broad-leaved, coniferous, and deciduous broad-leaved forest, with a vegetation combination sensitive to climate change. Higher resolution pollen records from the Shangyang Lake Wetland, located in the subtropical monsoon climate of the Baishanzu area in Zhejiang, China, were combined with environmental proxy data, such as data on loss on ignition and charcoal, to reconstruct the vegetation and climate changes since the Holocene. The results show that the climate was cool and dry during the early Holocene (11660-6580 cal. aBP), when the zonal vegetation changed from evergreen deciduous broad-leaved mixed forests dominated by evergreen Quercus (Quercus(E)), Castanopsis, deciduous Quercus (Quercus(D)), and Castanea to coniferous and broad-leaved mixed forests with rich Cryptomeria. Abies pollen spread to lower altitudes during the period 9620-8020 cal. aBP with Abies beshanzuensis covering large areas of land. The increased in the East Asian summer monsoon from 6580 to 2040 cal. aBP led to the Holocene Climate Optimum, when the climate was particularly warm and humid. The zonal vegetation was middle subtropical evergreen broad-leaved forest dominated by Quercus(E), Castanopsis, and Cyclobalanopsis with particularly high forest coverage and few fire events. For the last 2000 years, coniferous and broad-leaved mixed forests, mainly Pinus taiwanensis, have dominated the vegetation in the area. Sharp increase in such flora was observed after the year 980. Decreased temperature, cold climate, and increased anthropogenic disturbances have resulted in a substantial reduction in the arboreal pollen content, including Quercus, Castanopsis, Castanea, and Ilex, and an increase in Pinus and Poaceae. The results of this study will play a positive role in fully understanding the historical background and internal mechanisms of subtropical forest changes
Different grassland managements significantly change carbon fluxes in an alpine meadow
No full textAlpine meadow plays vital roles in regional animal husbandry and the ecological environment. However, different grassland managements affect the structure and function of the alpine meadow. In this study, we selected three typical grassland managements including free grazing, enclosure, and artificial grass planting and conducted a field survey to study the effects of grassland managements on carbon fluxes in an alpine meadow. The carbon fluxes were observed by static chamber and environmental factors including vegetation and soil characteristics were measured simultaneously. Our results show that the alpine meadow was a CO2 and CH4 sink, and grassland managements had a significant effect on all CO2 fluxes, including gross ecosystem production (GEP, P 0.05). The ranking of GEP under the different grassland managements was enclosure > free grazing > artificial grass planting. Furthermore, NEP and ER at enclosure plots were significantly higher than those of the free grazing and artificial grass planting plots. In addition, different grassland managements also affected the vegetation and soil characteristics of the alpine meadow. The aboveground biomass of artificial grass planting was significantly higher than that of the free grazing and enclosure plots. The vegetation coverage under three different grassland managements was ranked in the order of enclosure > artificial grass planting > free grazing and significant differences were observed among them. Moreover, significant differences in the number of species (P< 0.01) and the Margalef richness index (P< 0.05) were detected under three different grassland managements. Further analysis of the relationship between environmental factors and carbon fluxes revealed that GEP and NEP of the alpine meadow were positively correlated with vegetation coverage, the number of species, and the Margalef richness index. Therefore, grassland restoration should be configured with multiple species, which could improve carbon sink capacity while considering the functions of grassland restoration and production
Seed viability testing for research and conservation of epiphytic and terrestrial orchids
No full textBackground Seed viability testing is essential in plant conservation and research. Seed viability testing determines the success of ex-situ conservation efforts, such as seed banking but commonly testing protocols of orchids lack consistency and accuracy, therefore, there is a need to select an appropriate and reliable viability test, especially when conducting comparative studies. Here, we evaluated the suitability of three seed viability tests, Evans blue test (EB), Fluorescein diacetate test (FDA) and Tetrazolium test (TTC), with and without sterilization, on seeds of 20 orchid species, which included five epiphytes and fifteen terrestrials, using both fresh seeds and seeds stored at - 18 oC for 6 to 8 years. Results We found that sterilization and lifeform of seeds affected seed viability across all tests but the storage time was not an influential factor. Sterilization negatively affected seed viability under EB and FDA test conditions but increased the detection of viable seeds in the TTC test in both epiphytic and terrestrial species. The EB test, when administered without sterilization provided the highest viability results. Being non-enzymatic unlike TTC and FDA tests, as expected, the EB test was the most reliable with similar results between sterilized and not sterilized seeds for most epiphytic and terrestrial species as well as when compared between groups. Conclusions The lifeform of the species and seed sterilization prior to testing are important influential factors in orchid seed viability testing. Since EB test was found to be reliable we recommend the EB test for seed viability assessment in orchids rather than the less reliable but commonly used TTC test, or the FDA test, which require more expensive and sophisticated instrumentation. Since storage time was not an influential factor in orchid seed viability testing, the recommendations of this study can be used for both fresh as well as long-term stored orchid seeds. This is helpful for research and especially for conservation measures such as seed banking. However, due to the species specificity of the bio-physiology of orchids, we call for comprehensive viability test assessment in the hyper diverse orchid family to be extended to a greater number of species to facilitate efficient conservation and research
Nitrogen deposition increases xylem hydraulic sensitivity but decreases stomatal sensitivity to water potential in two temperate deciduous tree species
No full textAlthough the effects of nitrogen deposition on tree water relations are studied extensively, its impact on the relative sensitivities of stomatal and xylem hydraulic conductance to vapor pressure deficit and water potential is still poorly understood. This study investigated the effects of a 7-year N deposition treatment on the responses of leaf water relations and sensitivity of canopy stomatal conductance to vapor pressure deficit (VPD) and water potential, as well as the sensitivity of branch hydraulic conductance to water potential in a dominant tree species (Quercus wutaishanica) andan associated tree species (Acer mono) in a temperate forest. It was found that the N deposition increased stomatal sensitivity to VPD, decreased stomatal sensitivity to water potential, and increased the vulnerability of the hydraulic system to cavitation in both species. The standardized stomatal sensitivity to VPD, however, was not affected by the N deposition, indicating that the stomata maintained the ability to regulate the water balance under nitrogen deposition condition. Although the increased stomatal sensitivity to VPD could compensate the decreased stomatal sensitivity to water potential to some extent, the combined response would increase the percentage loss of hydraulic conductivity (PLC) when 50 % loss in stomatal conductance occurred, particularly in the dominant species Q. wutaishanica. The result indicates that N deposition would increase the risk of hydraulic failure in those species if the soil and/or air becomes drier under future climate change scenarios. The results of the study can have significant implications on the modelling of ecosystem vulnerability to drought under the scenario of atmospheric nitrogen deposition
Temporal and spatial comparisons of angiosperm diversity between eastern Asia and North America
No full textContrasting community responses of root and soil dwelling fungi to extreme drought in a temperate grassland
No full textFungal communities inhabiting plant roots and the soil diverge because they are shaped by differences in abiotic environment and plant filtering. Therefore, these two communities will also likely respond differently to climate change. However, such responses are poorly understood, especially for climate extremes with increasing fre-quency and intensity. Based on a long-term field experiment that simulated two types of extreme drought (chronic/intense) of once-in-20-year occurrence in the temperate grassland, we studied the response of soil and root fungal communities to extreme drought in association with plant communities. The species richness, community composition, and network stability of the root fungi were sensitive to extreme drought and showed legacy effects during recovery; notably, these responses were independent of extreme drought types. The sensitivity of the root community was mainly driven by rare symbiotic and saprotrophic fungal species, with abundant species remaining stable. In contrast, except for species relative abundances, soil fungal communities were resistant to drought. Structural equation modelling revealed that plant communities mediate drought ef-fects on root fungal communities but not soil communities. Our findings highlight the climate sensitivity of root fungal communities and their response asymmetry to soil communities, with potentially profound consequences for ecosystem stability and functionality
Condensation of SEUSS promotes hyperosmotic stress tolerance in Arabidopsis
No full textOsmotic stress imposed by drought and high salinity inhibits plant growth and crop yield. However, our current knowledge on the mechanism by which plants sense osmotic stress is still limited. Here, we identify the transcriptional regulator SEUSS (SEU) as a key player in hyperosmotic stress response in Arabidopsis. SEU rapidly coalesces into liquid-like nuclear condensates when extracellular osmolarity increases. The intrinsically disordered region 1 (IDR1) of SEU is responsible for its condensation. IDR1 undergoes conformational changes to adopt more compact states after an increase in molecular crowding both in vitro and in cells, and two predicted alpha-helical peptides are required. SEU condensation is indispensable for osmotic stress tolerance, and loss of SEU dramatically compromises the expression of stress tolerance genes. Our work uncovers a critical role of biomolecular condensates in cellular stress perception and response and expands our understanding of the osmotic stress pathway
Intensity and Duration of Nitrogen Addition Jointly Alter Soil Nutrient Availability in a Temperate Grassland
No full textIncreasing N input can alter soil nutrient availability and influence plant growth. Previous studies focused on N addition effects on N and P availability, while less on other mineral nutrients. Besides, how N addition duration affects nutrient availability has remained unclear. Based on a simulative N deposition experiment in a typical steppe with four N addition levels (0, 2, 10, and 50 g m(-2) yr(-1)) under three N addition duration (2, 5, and 10 years), we determined contents of 10 mineral nutrients in surface soils. In the 0-10 cm soil, short-term N addition (2-year) significantly increased exchangeable Ca (+7.2%) and decreased exchangeable Mg (-22.5%) as compared with the control, while decreased available Fe, Cu, and Zn, but increased Mn remarkably (+80.4%). Medium-term N addition (5-year) significantly raised soil total N and available Fe, Mn and Cu, while decreased total P and exchangeable Ca, Na and Mg. The response patterns of these nutrients were largely similar in the 10-20 cm soil, but were weaker and significant only at high N inputs (50 g m(-2) yr(-1)). Long-term N addition (10-year) significantly decreased contents of total base cations (K, Ca, Na, Mg) and micronutrients (Fe, Mn, Cu, Zn) by an average of 32.1% and 20.4%, respectively, across the two soil depths. Influences of pH and plant growth on micronutrients showed remarkable differences among different duration of N addition. These findings indicate that intensity and duration of N addition jointly alter soil nutrient availability and this should be considered in soil nutrient-cycling modeling