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[学术文献 ] Spatial transcriptome and single-cell RNA sequencing reveal the molecular basis of cotton fiber initiation development 进入全文
PLANT JOURNAL
Recent advances in single-cell transcriptomics have greatly expanded our knowledge of plant development and cellular responses. However, analyzing fiber cell differentiation in plants, particularly in cotton, remains a complex challenge. A spatial transcriptomic map of ovule from -1 DPA, 0 DPA, and 1 DPA in cotton was successfully constructed, which helps to explain the important role of sucrose synthesis and lipid metabolism during early fiber development. Additionally, single-cell RNA sequencing (scRNA-seq) further highlighted the cellular heterogeneity and identified clusters of fiber developmental marker genes. Integration of spatial and scRNA-seq data unveiled key genes SVB and SVBL involved in fiber initiation, suggesting functional redundancy between them. These findings provide a detailed molecular landscape of cotton fiber development, offering valuable insights for enhancing lint yield.
[学术文献 ] GWAS and eQTL analyses reveal genetic components influencing the key fiber yield trait lint percentage in upland cotton 进入全文
PLANT JOURNAL
Lint percentage is an important component of cotton yield traits and an important economic indicator of cotton production. The initial stage of fiber development is a critical developmental period that affects the lint percentage trait, but the genetic regulation of the initial stage of fiber development needs to be resolved. In this study, we used a genomewide association study (GWAS) to identify 11 quantitative trait loci (QTLs) related to lint percentage and identified a total of 13 859 expression QTL (eQTLs) through transcriptome sequencing of 312 upland cotton accessions. Candidate genes for improving the lint percentage trait were identified through transcriptome-wide association study (TWAS), colocalization analysis, and differentially expressed gene analysis. We located nine candidate genes through the TWAS, and prioritized two key candidate genes (Ghir_A12G025980 and Ghir_A12G025990) related to lint percentage through colocalization and differential expression analysis. We showed that two eQTL hotspots (Hot26 and Hot28) synergistically participate in regulating the biological pathways of fiber initiation and development. Additionally, we unlocked the potential of genomic variants in improving the lint percentage by aggregating favorable alleles in accessions. New accessions suitable for improving lint percentage were excavated.
[学术文献 ] Identification of salt-resilient cotton genotypes using integrated morpho-physiological and biochemical markers at the seedling stage 进入全文
Scientific Reports
Soil salinity drastically hinders cotton productivity (Gossypium hirsutum), and fiber quality. The current study evaluated morpho-physiological and biochemical responses of fifty cotton genotypes under different salinity levels (control, 12 dS/m, and 17 dS/m) at the seedling stage. The experiment was performed in a factorial complete randomized design with three replications. Significant genotype × treatment interactions were observed for most traits, including shoot length (SL), root length (RL), fresh and dry shoot weight (FSW, DSW), fresh and dry root weight (FRW, DRW), total soluble protein (TSP), proline content, and antioxidant enzymes. Severe salinity stress reduces shoot length (SL) and root length (RL) along with notable decreases in biomass and altered biochemical responses, including increased antioxidant activities and proline content, indicating stress adaptation. Moreover, PCA and Pearson’s correlation analyses unveiled strong positive and negative correlations among studied attributes while MGIDI analyses assist in determining the salt-resilient cotton genotypes under applied treatments. The best-performing genotypes under control conditions were G2, G8, and G12, while G7, G43, and G30 showed resilience under severe salinity stress. MGIDI effectively identified genotypes with outstanding salinity tolerance, such as G2, G43, G40, and G26, across all stress levels. This research assists in determining the salinity stress-tolerant cotton genotypes using morpho-physiological and biochemical parameters and MGIDI is used as a precise method for identifying salt-resilient cotton accessions.
[学术文献 ] PtrVINV2 is dispensable for cellulose synthesis but essential for salt tolerance in Populus trichocarpa Torr. and Gray 进入全文
PLANT BIOTECHNOLOGY JOURNAL
Invertase (EC.3.2.1.26), a key enzyme in sucrose breakdown, is crucial for cellulose synthesis. However, the function of the vacuolar invertase (VINV) in woody plants remains unclear. In this study, transgenic lines of Populus trichocarpa Torr. and Gray were generated to investigate the role of PtrVINV2 in wood formation and under high salinity stress. Compared to wild-type (WT), VINV activity in the developing xylem of knockout lines was reduced, resulting in a decrease in lignin content and an increase in hemicellulose content, while cellulose content remained unaffected. These changes in structural carbohydrate content were accompanied by reductions in xylem width and fibre cell wall thickness. The overexpression lines of the developing xylem exhibited opposite trends. Transcriptome analyses of developing xylem indicated that the expression level of PtrVINV2 affects the expression of genes involved in hemicellulose and lignin biosynthesis pathways, such as AXS, UAMs, HCT, COMT, CAD and peroxidases, while CesA expression remained unaffected. WGCNA analysis revealed that Potri.001G219100, Potri.009G106600 and Potri.002G081000 serve as 'hub' transcription factor genes within the structural/non-structural carbohydrate modules of PtrVINV2 transgenic lines, potentially involved in plant salt tolerance. Additionally, under 200 mmol/L NaCl treatment, the knockout lines exhibited increased salt sensitivity compared to WT. This increased sensitivity was accompanied by elevated activities of SOD, CAT and MDA, as well as higher sucrose content and reduced contents of glucose and fructose. The findings indicate that although PtrVINV2 is not essential for cellulose synthesis, it enhances salt tolerance in poplar and presents a promising candidate gene for breeding salt-tolerant poplar.
[学术文献 ] CYTOKININ DEHYDROGENASE suppression increases intrinsic water-use efficiency and photosynthesis in cotton under drought 进入全文
PLANT PHYSIOLOGY
Drought reduces endogenous cytokinin (CK) content and disturbs plant water balance and photosynthesis. However, the effect of higher endogenous CK levels (achieved by suppressing cytokinin dehydrogenase [CKX] genes) on plant water status and photosynthesis under drought stress is unknown. Here, pot experiments were conducted with wild-type (WT) cotton (Gossypium hirsutum) and 2 GhCKX suppression lines (CR-3 and CR-13) to explore the effect of higher endogenous CK levels on leaf water utilization and photosynthesis under drought stress. The GhCKX suppression lines had a higher leaf net photosynthetic rate (AN) and intrinsic water-use efficiency (iWUE) than WT under drought. This increase was attributed to the decoupling of stomatal conductance (gs) and mesophyll conductance (gm) in the suppression lines in response to drought. GhCKX suppression increased gm but maintained gs relative to WT under drought, and the increased gm was associated with altered anatomical traits, including decreased cell wall thickness (Tcw) and increased surface area of chloroplast-facing intercellular airspaces per unit leaf area (Sc/S), as well as altered cell wall composition, especially decreased cellulose levels. This study provides evidence that increased endogenous CK levels can simultaneously enhance AN and iWUE in cotton under drought conditions and establishes a potential mechanism for this effect. These findings provide a potential strategy for breeding drought-tolerant crops or exploring alternative methods to promote crop drought tolerance. Increasing endogenous cytokinin levels alters anatomical traits related to stomatal and mesophyll conductance, resulting in their decoupling and enhanced drought tolerance in cotton.
[学术文献 ] A cell fractionation and quantitative proteomics pipeline to enable functional analyses of cotton fiber development 进入全文
PLANT JOURNAL
Cotton fibers are aerial trichoblasts that employ a highly polarized diffuse growth mechanism to emerge from the developing ovule epidermis. After executing a complicated morphogenetic program, the cells reach lengths over 2 cm and serve as the foundation of a multi-billion-dollar textile industry. Important traits such as fiber diameter, length, and strength are defined by the growth patterns and cell wall properties of individual cells. At present, the ability to engineer fiber traits is limited by our lack of understanding regarding the primary controls governing the rate, duration, and patterns of cell growth. To gain insights into the compartmentalized functions of proteins in cotton fiber cells, we developed a label-free liquid chromatography mass spectrometry method for systems-level analyses of fiber proteome. Purified fibers from a single locule were used to fractionate the fiber proteome into apoplast (APOT), membrane-associated (p200), and crude cytosolic (s200) fractions. Subsequently, proteins were identified, and their localizations and potential functions were analyzed using combinations of size exclusion chromatography, statistical and bioinformatic analyses. This method had good coverage of the p200 and APOT fractions, the latter of which was dominated by proteins associated with particulate membrane-enclosed compartments. The apoplastic proteome was diverse, the proteins were not degraded, and some displayed distinct multimerization states compared to their cytosolic pool. This quantitative proteomic pipeline can be used to improve coverage and functional analyses of the cotton fiber proteome as a function of developmental time or differing genotypes.
