of Botany,Chinese Academy Of Sciences
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The transcription factor OsGATA6 regulates rice heading date and grain number per panicle
No full textHeading date, panicle architecture, and grain size are key traits that affect the yield of rice (Oryza sativa). Here, we identified a new gene, OsGATA6, whose product regulates heading date. Overexpression of OsGATA6 resulted in delayed heading, increased grain number, and decreased grain size. Knockdown lines generated by artificial microRNA (amiRNA) and CRISPR genome-edited lines of OsGATA6 both showed earlier heading, decreased grain number, and increased grain size. These results suggested that OsGATA6 negatively regulates heading date, positively regulates panicle development, and affects grain size. OsGATA6 was found to be constitutively expressed in rice, and strongly expressed in young leaves and panicles. In situ hybridization analyses showed that OsGATA6 was specifically localized in superficial cells of the panicle primordium. Overexpression lines show decreased expression of RFT1 and Hd3a, which promote heading. OsMFT1, which delays heading date and increases grain number, was down-regulated in amiRNA lines. Further analyses showed that OsGATA6 could bind to the promoter of OsMFT1 and induce its expression, thereby regulating heading date and panicle development. Overexpression of OsGATA6 in Arabidopsis resulted in repressed expression of AtFT and late flowering, suggesting that its function is similar. Taken together, we have identified a new GATA regulator that influences rice heading date and grain number, which potentially increases rice yield. OsGATA6inhibits rice heading and increases grain number through transcriptional regulation of MFT1, and its overexpression has the potential to enhance yield through increasing grain number
Shifts in understory plant composition induced by nitrogen addition predict soil fungal beta diversity in a boreal forest
No full textAboveground-belowground interactions are important drivers of terrestrial ecosystem structure and function. However, changes in soil microbial diversity caused by shifts in the plant community composition in the context of nitrogen (N) deposition remain poorly understood in boreal forests. Based on a long-term experiment of N addition at rates of 0, 20, 50, and 100 kg N ha(-1) year(-1) in a boreal forest in northeastern China, we found that N addition resulted in an increasing dissimilarity in understory plant community composition along the elevated N addition rates. N addition had no effects on the soil microbial alpha diversity but did alter the soil microbial beta diversity. The shifts in the soil bacterial beta diversity following N addition were correlated with soil pH, whereas the changes in the soil fungal beta diversity were explained by changes in the understory plant composition. Since soil fungi play an irreplaceable role in boreal forests, our findings imply that N deposition-induced changes in understory plant community structures might be associated with changes in soil fungal community composition, with potential profound consequences on soil nutrient dynamics and soil carbon cycling
AtNusG, a chloroplast nucleoid protein of bacterial origin linking chloroplast transcriptional and translational machineries, is required for proper chloroplast gene expression in Arabidopsis thaliana
No full textIn Escherichia coli, transcription-translation coupling is mediated by NusG. Although chloroplasts are descendants of endosymbiotic prokaryotes, the mechanism underlying this coupling in chloroplasts remains unclear. Here, we report transcription-translation coupling through AtNusG in chloroplasts. AtNusG is localized in chloroplast nucleoids and is closely associated with the chloroplast PEP complex by interacting with its essential component PAP9. It also comigrates with chloroplast ribosomes and interacts with their two components PRPS5 (uS5c) and PRPS10 (uS10c). These data suggest that the transcription and translation machineries are coupled in chloroplasts. In the atnusg mutant, the accumulation of chloroplast-encoded photosynthetic gene transcripts, such as psbA, psbB, psbC and psbD, was not obviously changed, but that of their proteins was clearly decreased. Chloroplast polysomic analysis indicated that the decrease in these proteins was due to the reduced efficiency of their translation in this mutant, leading to reduced photosynthetic efficiency and enhanced sensitivity to cold stress. These data indicate that AtNusG-mediated coupling between transcription and translation in chloroplasts ensures the rapid establishment of photosynthetic capacity for plant growth and the response to environmental changes. Therefore, our study reveals a conserved mechanism of transcription-translation coupling between chloroplasts and E. coli, which perhaps represents a regulatory mechanism of chloroplast gene expression. This study provides insights into the underlying mechanisms of chloroplast gene expression in higher plants
Temporal shifts in the relative importance of climate and leaf litter traits in driving litter decomposition dynamics in a Chinese transitional mixed forest
No full textPurpose To assess the direction and strength of climate and leaf litter trait effects on decomposition dynamics throughout the litter decomposition process. Methods We performed a three-year-long litterbag translocation experiment along an elevational gradient in a transitional mixed forest in China. We explored temporal shifts in the relative contribution of microclimate and litter traits of seven dominant species to mass loss throughout the decomposition process. Results Air temperature and soil moisture imparted no significant effects on mass loss in the initial decomposition stage (0-6 months) but exerted positive effects after 6 months' incubation (p < 0.05). Initial specific leaf area (SLA) was positively associated with mass loss only during the early decomposition stages (0-12 months). Litter P concentration was positively while N concentration was negatively associated with mass loss for almost all decomposition stages. Both litter Mg and Ca concentrations were negatively associated with mass loss throughout the whole decomposition process (p < 0.05). The relative contribution of microclimate was weaker than that of litter traits during the early stages but increased in the late decomposition stage (after 36 months). SLA and Mg were the most important traits during the early stages (0-12 months), whereas N and Mg were relatively stronger during the later stages (30-36 months). Conclusion Our results have highlighted that microclimate (particularly temperature) exerted dominant control over later-stage litter decomposition. Often-overlooked litter traits such as Mg, are key potential drivers of litter decomposition dynamics and should be more explicitly incorporated into current biogeochemical models to better understand litter-driven nutrient and carbon cycling
Carbonate-Induced Chemical Reductants Are Responsible for Iron Acquisition in Strategy I Wild Herbaceous Plants Native to Calcareous Grasslands
No full textSignificant progress has been made in understanding Strategy I iron (Fe) acquisition using crop/model plants under controlled conditions in laboratories. However, plant species native to calcareous soils may have evolved unique strategies for adaptation to high carbonate/pH-induced Fe deficiency. Until now, little information is available on the Fe acquisition mechanisms in these plants. Here, we explored the Fe acquisition mechanisms in wild dicot species native to calcareous grasslands, by monitoring the Fe nutrition-related rhizosphere processes in field and greenhouse conditions. Most of these wild species displayed comparable shoot Fe concentration to those of crops, and some dicots actually accumulated very high shoot Fe. However, these species did not exhibit ferric reductase oxidase (FRO)-dependent Strategy I responses to Fe deficiency, including visual rhizosphere acidification and increased Fe3+ reduction. In contrast, chemical reductants exuded by roots of dicots were responsible for Fe3+ reduction in these wild plants. These features were not observed in the FRO-dependent Strategy I crop plant cucumber. Neither leaf chlorophyll nor shoot/root Fe was depressed by 10% CaCO3 application in all the examined wild species. Furthermore, their root exudation was significantly activated by CaCO3, leading to an increased Fe3+ reduction. We show that chemical reductant-mediated Fe3+ reduction occurs preferentially in these wild dicots and that these mechanisms are not sensitive to high soil carbonate/pH. Our findings support that Fe acquisition in Strategy I wild plants native to calcareous soils is substantially different from the enzyme-dependent system of Strategy I plants
Coordination of leaf functional traits under climatic warming in an arid ecosystem
No full textBackground Climatic warming is increasing regionally and globally, and results concerning warming and its consequent drought impacts have been reported extensively. However, due to a lack of quantitative analysis of warming severities, it is still unclear how warming and warming-induced drought influence leaf functional traits, particularly how the traits coordinate with each other to cope with climatic change. To address these uncertainties, we performed a field experiment with ambient, moderate and severe warming regimes in an arid ecosystem over 4 years. Results Severe warming significantly reduced the specific leaf area and net photosynthetic rate with a relatively stable change and even enhancement under moderate warming, especially showing species-specific performance. The current results largely indicate that a coordinated trade-off can exist between plant functional traits in plant communities in a dryland ecosystem under ambient temperature conditions, which is strongly amplified by moderate warming but diminished or even eliminated by severe warming. Based on the present findings and recent results in the relevant literature, we advance the ecological conceptual models (e.g., LES and CSR) in the response to climatic warming in arid grassland communities, where the few key species play a crucial role by balancing their functional performances to cope with environmental change. Conclusion Our results highlight the importance of coordination and/or trade-off between leaf functional traits for understanding patterns of climatic change-induced vegetation degradation and suggest that the plant community composition in these drylands could be shifted under future climate change
Inhibitory Effects of CaCl2 and Pectin Methylesterase on Fruit Softening of Raspberry during Cold Storage
No full textQuality of raspberry fruit experiences a rapid decline after harvest due to its vulnerable texture and high moisture content. Application of calcium chloride (CaCl2) combined with pectin methylesterase (PME) is efficient in delaying fruit softening. In this study, the effects of exogenous CaCl2 alone or in combination with PME on the structure of the cell wall, the molecular properties of pectin, and the amount of free water of raspberry during postharvest storage were investigated. The results showed that CaCl2 combined with PME treatment could maintain fruit firmness and inhibit weight loss. The treatment of CaCl2+PME maintained the cell wall structure via sustaining middle lamella integrity and reducing the activities of cell wall-degrading enzymes, such as polygalacturonase, pectin methylesterase, beta-galactosidase, alpha-L-arabinofuranosidase, and beta-xylosidase. In addition, CaCl2+PME treatment could effectively increase the content of chelate-soluble pectin (CSP) and develop a cross-linked structure between Ca2+ and CSP. Moreover, CaCl2+PME treatment was of benefit in maintaining free water content. CaCl2 in combination with PME treatment could be a promising method for inhibiting softening and maintaining the quality of postharvest raspberry during cold storage
A genome for Cissus illustrates features underlying its evolutionary success in dry savannas
No full textCissus is the largest genus in Vitaceae and is mainly distributed in the tropics and subtropics. Crassulacean acid metabolism (CAM), a photosynthetic adaptation to the occurrence of succulent leaves or stems, indicates that convergent evolution occurred in response to drought stress during species radiation. Here we provide the chromosomal level assembly of Cissus rotundifolia (an endemic species in Eastern Africa) and a genome-wide comparison with grape to understand genome divergence within an ancient eudicot family. Extensive transcriptome data were produced to illustrate the genetics underpinning C. rotundifolia's ecological adaption to seasonal aridity. The modern karyotype and smaller genome of C. rotundifolia (n=12, 350.69 Mb/1C), which lack further whole-genome duplication, were mainly derived from gross chromosomal rearrangements such as fusions and segmental duplications, and were sculpted by a very recent burst of retrotransposon activity. Bias in local gene amplification contributed to its remarkable functional divergence from grape, and the specific proliferated genes associated with abiotic and biotic responses (e.g. HSP-20, NBS-LRR) enabled C. rotundifolia to survive in a hostile environment. Reorganization of existing enzymes of CAM characterized as diurnal expression patterns of relevant genes further confer the ability to thrive in dry savannas
Vegetation Classification and Distribution Patterns in the South Slope of Yarlung Zangbo Grand Canyon National Nature Reserve, Eastern Himalayas
No full textYarlung Zangbo Grand Canyon National Nature Reserve has the most complete vertical vegetation belts in China. However, identification and distribution of vertical vegetation belts is still uncertain and in debate. To explore the above issues, 190 plots were surveyed within the reserve from 2019 to 2021. Based on the vegetation plot data, cluster analysis, ordination analysis, and biodiversity statistics were performed to reveal the structure of vertical vegetation belts-the driving factors of vegetation distribution-to describe the main biodiversity patterns. Five vertical vegetation belts were identified by clustering. NMDS ordination showed that the main factor of vegetation distribution is elevation. Based on the results of the analysis and previous literature, a new scheme of vertical vegetation belts in the south slope of the reserve was proposed. There was a lower montane seasonal rainforest belt (600-1100 m), a lower montane evergreen broadleaf forest belt (1100-1800 m), a middle montane semi-evergreen broadleaf forest belt (1800-2400 m), a subalpine evergreen needleleaf forest belt (2400-3800 m), a alpine shrubland and meadow belt (3800-4400 m), an alpine sparse vegetation belt (4400-4800 m), and a nival belt (4800-7782 m). Among them, the seasonal rainforest belts are the northernmost distribution of this type, and the semi-evergreen broadleaf forest belts exist only in the Eastern Himalayas. The study showed a unimodal pattern in plant species diversity, the peak of which is about 1900 m. The middle montane semi-evergreen broadleaf forest belt had the highest species diversity in the reserve. This study settled the issues regarding the vertical vegetation belts, the main drivers of vegetation and assessment of plant species diversity in the south slope of the Yarlung Zangbo Grand Canyon National Nature Reserve. It provides essential support for the management and conservation of these ecosystems in the reserve
Subgenome dominance and its evolutionary implications in crop domestication and breeding
No full textPolyploidization or whole-genome duplication (WGD) is a well-known speciation and adaptation mechanism in angiosperms, while subgenome dominance is a crucial phenomenon in allopolyploids, established following polyploidization. The dominant subgenomes contribute more to genome evolution and homoeolog expression bias, both of which confer advantages for short-term phenotypic adaptation and long-term domestication. In this review, we firstly summarize the probable mechanistic basis for subgenome dominance, including the effects of genetic [transposon, genetic incompatibility, and homoeologous exchange (HE)], epigenetic (DNA methylation and histone modification), and developmental and environmental factors on this evolutionary process. We then move to Brassica rapa, a typical allopolyploid with subgenome dominance. Polyploidization provides the B. rapa genome not only with the genomic plasticity for adapting to changeable environments, but also an abundant genetic basis for morphological variation, making it a representative species for subgenome dominance studies. According to the 'two-step theory', B. rapa experienced genome fractionation twice during WGD, in which most of the genes responding to the environmental cues and phytohormones were overretained, enhancing subgenome dominance and consequent adaption. More than this, the pangenome of 18 B. rapa accessions with different morphotypes recently constructed provides further evidence to reveal the impacts of polyploidization and subgenome dominance on intraspecific diversification in B. rapa. Above and beyond the fundamental understanding of WGD and subgenome dominance in B. rapa and other plants, however, it remains elusive why subgenome dominance has tissue- and spatiotemporalspecific features and could shuffle between homoeologous regions of different subgenomes by environments in allopolyploids. We lastly propose acceleration of the combined application of resynthesized allopolyploids, omics technology, and genome editing tools to deepen mechanistic investigations of subgenome dominance, both genetic and epigenetic, in a variety of species and environments. We believe that the implications of genomic and genetic basis of a variety of ecologically, evolutionarily, and agriculturally interesting traits coupled with subgenome dominance will be uncovered and aid in making new discoveries and crop breeding