of Botany,Chinese Academy Of Sciences
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Integrated phylogenomic analyses unveil reticulate evolution in Parthenocissus (Vitaceae), highlighting speciation dynamics in the Himalayan-Hengduan Mountains
No full textHybridization caused by frequent environmental changes can lead both to species diversification (speciation) and to speciation reversal (despeciation), but the latter has rarely been demonstrated. Parthenocissus, a genus with its trifoliolate lineage in the Himalayan-Hengduan Mountains (HHM) region showing perplexing phylogenetic relationships, provides an opportunity for investigating speciation dynamics based on integrated evidence.We investigated phylogenetic discordance and reticulate evolution in Parthenocissus based on rigorous analyses of plastome and transcriptome data. We focused on reticulations in the trifoliolate lineage in the HHM region using a population-level genome resequencing dataset, incorporating evidence from morphology, distribution, and elevation.Comprehensive analyses confirmed multiple introgressions within Parthenocissus in a robust temporal-spatial framework. Around the HHM region, at least three hybridization hot spots were identified, one of which showed evidence of ongoing speciation reversal.We present a solid case study using an integrative methodological approach to investigate reticulate evolutionary history and its underlying mechanisms in plants. It demonstrates an example of speciation reversal through frequent hybridizations in the HHM region, which provides new perspectives on speciation dynamics in mountainous areas with strong topographic and environmental heterogeneity
Effects of Moderate Water Deficit on the Accumulation and Translocation of Stem Non-Structural Carbohydrates, Yield and Yield Components in a Sink-Limited Rice Variety Under Elevated CO2 Concentration
No full textTo investigate the effects of moderate water deficit (MD) on ? non-structural carbohydrates (NSC), ? yield and yield components in a sink-limited rice variety under elevated CO2 concentration ([CO2]), a japonica rice (Oryza sativa L.) cultivar Nangeng 9108 was planted at ambient [CO2] (a[CO2]) and elevated [CO2] (e[CO2], a[CO2] + 200 ppm) in open-top chambers with MD treatment set during grain filling stage. The content, accumulation, and translocation of NSC as well as yield components were determined, and the relationships among them were analyzed. Compared to e[CO2] + CK, e[CO2] + MD treatment decreased the content (by 42%) and accumulation (by 57%) of NSC in stems, and greatly promoted NSC translocation (by 325%). At MD treatment, e[CO2] stimulated ATM(NSC) and AC(NSC), and the re-accumulation of stem NSC at maturity was limited under both CO2 treatment. With higher NSC translocation, the 1000-grain weight was lowered, but seed setting rate and harvest index were improved. Grain yield of Nangeng 9108 was not changed by MD treatment, which implied that the sink-limited rice varieties may be more adaptable to balance the survival (root growth to obtain more water) and reproduction with potential drought stress at future CO2-enriched environment
Predicting ecosystem productivity based on plant community traits
No full textWith the rapid accumulation of plant trait data, major opportunities have arisen for the integration of these data into predicting ecosystem primary productivity across a range of spatial extents. Traditionally, traits have been used to explain physiological productivity at cell, organ, or plant scales, but scaling up to the ecosystem scale has remained challenging. Here, we show the need to combine measures of community-level traits and environmental factors to predict ecosystem productivity at landscape or biogeographic scales. We show how theory can extend the production ecology equation to enormous potential for integrating traits into ecological models that estimate productivity-related ecosystem functions across ecological scales and to anticipate the response of terrestrial ecosystems to global change
MYB30 and MYB14 form a repressor-activator module with WRKY8 that controls stilbene biosynthesis in grapevine
No full textWhen exposed to pathogen infection or ultraviolet (UV) radiation, grapevine (Vitis vinifera) plants rapidly accumulate the stilbenoid resveratrol (Res) with concomitant increase of stilbene synthase (STS), the key enzyme in stilbene biosynthesis. Although a few transcription factors have been shown to regulate STSs, the molecular mechanism governing the regulation of STSs is not well elucidated. Our previous work showed that a VvMYB14-VvWRKY8 regulatory loop fine-tunes stilbene biosynthesis in grapevine through protein-protein interaction; overexpression of VvWRKY8 down-regulates VvMYB14 and VvSTS15/21; and application of exogenous Res up-regulates WRKY8 expression. Here, we identified an R2R3-MYB repressor, VvMYB30, which competes with the activator VvMYB14 for binding to the common binding sites in the VvSTS15/21 promoter. Similar to VvMYB14, VvMYB30 physically interacts with VvWRKY8 through their N-termini, forming a complex that does not bind DNA. Exposure to UV-B/C stress induces VvMYB14, VvWRKY8, and VvSTS15/21, but represses VvMYB30 in grapevine leaves. In addition, MYB30 expression is up-regulated by VvWRKY8-overexpression or exogenous Res. These findings suggest that the VvMYB14-VvWRKY8-VvMYB30 regulatory circuit allows grapevine to respond to UV stress by producing Res and prevents over-accumulation of Res to balance metabolic costs. Our work highlights the stress-mediated induction and feedback inhibition of stilbene biosynthesis through a complex regulatory network involving multiple positive and negative transcriptional regulators. VvMYB30 is involved in a complex regulatory network containing multiple positive and negative transcriptional regulators that fine-tunes stilbene biosynthesis under ultraviolet stress
Soil organic carbon sourcing variance in the rhizosphere vs. non-rhizosphere of two mycorrhizal tree species
No full textSoil organic carbon (SOC) plays a central role in ecosystem carbon sequestration and climate change mitigation, and its stability and dynamics are related to sourcing from microbial vs. plant residues. However, SOC sourcing and its regulating mechanisms remain poorly understood in soil's most bioactive compartment, the rhizosphere, which may differ from non-rhizosphere and under different mycorrhizal tree species. To fill the knowledge gap, here we collect the rhizosphere and non-rhizosphere soils under an arbuscular mycorrhizal (AM; Castanopsis eyrie) vs. an ectomycorrhizal (ECM) tree species (Pinus massoniana) of varied tree diameters (i.e., ages) in the Gutianshan subtropical forest of China. Plant and microbial residual components are quantified by lignin phenols and amino sugars, respectively. Coupled with the measurements of soil, microbial community and plant litter properties, we assess potential mechanisms (i.e., saprotrophic bacteria competition, microbial necromass recycling/reuse, and substrate quality control) influencing the distribution of plant and microbial residues in the rhizosphere vs. non-rhizosphere. We show that lignin phenols are more concentrated in rhizosphere than nonrhizosphere SOC, especially under the ECM trees showing inhibited saprotrophic decomposition induced by competition between ECM fungi and (saprophytic) bacteria. Amino sugars are also more concentrated in the rhizosphere of ECM trees due to ECM fungal contribution, but not under AM trees exhibiting reduced fungal necromass stability partially reflected by low biomass-normalized necromass accumulation coefficients in the rhizosphere. As a result, ratios of amino sugars to lignin phenols are relatively lower in the rhizosphere than nonrhizosphere under AM tree, challenging the presumed microbial dominance in rhizosphere carbon accumulation. These results highlight differences in and controls on rhizosphere SOC sourcing related to different mycorrhizal tree species, providing new information on the mechanisms regulating soil carbon dynamics in root-soil systems
An endoplasmic reticulum-associated degradation-related E2-E3 enzyme pair controls grain size and weight through the brassinosteroid signaling pathway in rice
No full textGrain size is an important agronomic trait, but our knowledge about grain size determination in crops is still limited. Endoplasmic reticulum (ER)-associated degradation (ERAD) is a special ubiquitin proteasome system that is involved in degrading misfolded or incompletely folded proteins in the ER. Here, we report that SMALL GRAIN 3 (SMG3) and DECREASED GRAIN SIZE 1 (DGS1), an ERAD-related E2-E3 enzyme pair, regulate grain size and weight through the brassinosteroid (BR) signaling pathway in rice (Oryza sativa). SMG3 encodes a homolog of Arabidopsis (Arabidopsis thaliana) UBIQUITIN CONJUGATING ENZYME 32, which is a conserved ERAD-associated E2 ubiquitin conjugating enzyme. SMG3 interacts with another grain size regulator, DGS1. Loss of function of SMG3 or DGS1 results in small grains, while overexpression of SMG3 or DGS1 leads to long grains. Further analyses showed that DGS1 is an active E3 ubiquitin ligase and colocates with SMG3 in the ER. SMG3 and DGS1 are involved in BR signaling. DGS1 ubiquitinates the BR receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) and affects its accumulation. Genetic analysis suggests that SMG3, DGS1, and BRI1 act together to regulate grain size and weight. In summary, our findings identify an ERAD-related E2-E3 pair that regulates grain size and weight, which gives insight into the function of ERAD in grain size control and BR signaling. An endoplasmic reticulum-associated degradation-related E2-E3 pair affects grain size in rice through the brassinosteroid signaling pathway
Depth-Dependent Controls Over Soil Organic Carbon Stock across Chinese Shrublands
No full textSoil organic carbon (SOC) in shrublands is an important component of global carbon cycling. However, there is a dearth of large-scale systematic observations of SOC stocks at different soil depths, and it remains uncertain whether and how the relative importance of biotic and abiotic variables in regulating SOC stocks changes with soil depth. Here, we quantified large-scale patterns and controlling factors of SOC storage per area (SOCD, kg m(-2)) for both topsoils (0-30 cm) and subsoils (30-100 cm) by taking full advantage of a consistent stratified random sampling study of one-meter soil profiles across 1211 sites in Chinese shrublands. We found that subsoils stored about 53.30% of total SOCD, falling into the range of previously reported values for terrestrial ecosystems. SoilGrids250m model-derived assessments overestimated SOCD by 13.72 and 65.49% for topsoils and subsoils, respectively. The effects of climate means and seasonality on SOCD were equally strong in both topsoils and subsoils. The predominant effects of edaphic properties on SOCD were more robust in subsoils than in topsoils. Belowground biomass of shrublands was the only significant predictor of topsoil SOCD, but it did not predict subsoil SOCD accurately. These findings have refined our understanding of the pivotal role of shrublands in SOC storage and sequestration potential and could serve as an ecologically valuable baseline for large-scale improvement and validation of depth-dependent SOC dynamics for multilayer SOC modules in Earth Systems Models
Male-linked gene TsRPL10a′ in androdioecious tree Tapiscia sinensis: implications for sex differentiation by influencing gynoecium development
No full textThe mechanism of sex differentiation in androdioecy is of great significance for illuminating the origin and evolution of dioecy. Tapiscia sinensis Oliv. is a functionally androdioecious species with both male and hermaphroditic individuals. Male flowers of T. sinensis lack the ovules of gynoecia compared with hermaphrodites. To identify sex simply and accurately, and further find the potential determinants of sex differentiation in T. sinensis, we found that TsRPL10a ', a duplicate of TsRPL10a, was a male-linked gene. The promoter (5 ' untranslated region and the first intron) of TsRPL10a ' can be used to accurately identify sex in T. sinensis. TsRPL10a is a ribosomal protein that is involved in gynoecium development, and sufficient ribosomal levels are necessary for female gametogenesis. The expression level of TsRPL10a was significantly downregulated in male flower primordia compared with hermaphrodites. The RNA fluorescence in situ hybridization (FISH) assay demonstrated that TsRPL10a was almost undetectable in male gynoecia at the gynoecial ridge stage, which was a key period of ovule formation by scanning electron microscope observation. In male flowers, although the promoter activity of TsRPL10a was significantly higher than TsRPL10a ' verified by transgenic Arabidopsis thaliana, the transcriptional expression ratio of TsRPL10a was obviously lower than TsRPL10a ' and reached its lowest at the gynoecial ridge stage, indicating the existence of a female suppressor. The promoter similarity of TsRPL10a and TsRPL10a ' was only 45.29%; the genomic sequence similarity was 89.8%; four amino acids were altered in TsRPL10a '. The secondary structure of TsRPL10a ' was different from TsRPL10a, and TsRPL10a ' did not exhibit FISH and GUS expression in the gynoecium the way TsRPL10a did. From the perspective of RT-qPCR, its high expression level, followed by the low expression level of TsRPL10a in male flowers, indicates its antagonism function with TsRPL10a. The evolutionary analysis, subcellular localization and flower expression pattern suggested that TsRPL10a might be functionally conserved with AtRPL10aA, AtRPL10aB and AtRPL10aC in A. thaliana. Overall, we speculated that TsRPL10a and its duplicate TsRPL10a ' might be involved in sex differentiation by influencing gynoecium development in T. sinensis
A meta-analysis on the responses of soil microbial biomass and community structure to antibiotics
No full textThe overuse of antibiotics over the last few decades is of serious concern worldwide, and may lead to profound alterations in the biomass and structure of soil microbial communities, thus posing threats to soil ecosystems. However, on a global scale, the effects of antibiotics on soil microbial biomass and community structure remain elusive. Here, by performing 66 paired observations, we conducted one of the first global meta-analysis to evaluate the effects of various antibiotics on soil microbial communities and to explore the underlying mechanisms. Our results showed that antibiotics suppressed soil microbial biomass (indicated by PLFA) by 17 %, bacterial biomass by 17 %, and fungal biomass by 10 %. The ratio of bacteria to fungi biomass was decreased for all antibiotic types. The negative effects of antibiotics on soil microbial community and bacteria biomass attenuated with time. Additionally, the response of bacteria biomass to antibiotics, which is regulated by mean annual temperature and precipitation through soil pH and soil total nitrogen, diminished with latitude. Collectively, this study illustrates the global patterns and drivers of antibiotic-induced negative influences on microbial communities in soils, and can help identify global hotspots facing the negative effects of increasing anthropogenic usage of antibiotics
Uncovering the hidden diversity of the rosette-forming Selaginella tamariscina group based on morphological and molecular data
No full textPlants of the Selaginella tamariscina group are common rosette-forming species showing great morphological variability across their distribution range. Integrating chloroplast genome data and morphological evidence, we studied the species delimitation within this group. We newly sequenced the complete chloroplast genomes of 53 individuals representing almost the entire geographical distribution of this group. Our phylogenetic analyses yielded a consistent topology dividing the S. tamariscina group into five major clades, which is further supported by principal component analysis of 18 morphological characters taken from 80 herbarium specimens. Based on the results of molecular analyses and morphological studies combined with the distribution information, we finally recognize five species in the S. tamariscina group, including two new species (S. algida sp. nov., S. graniticola sp. nov.), and one new subspecies (S. pulvinata subsp. qinbashanica subsp. nov.)