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[学术文献 ] Novel resources to investigate leaf plasmodesmata formation in C3 and C4 monocots 进入全文
PLANT JOURNAL
Plasmodesmata (PD) are nanochannels that facilitate cell-to-cell transport in plants. More productive and photosynthetically efficient C4 plants form more PD at the mesophyll (M)-bundle sheath (BS) interface in their leaves than their less efficient C3 relatives. In C4 leaves, PD play an essential role in facilitating the rapid metabolite exchange between the M and BS cells to operate a biochemical CO2 concentrating mechanism, which increases the CO2 partial pressure at the site of Rubisco in the BS cells and hence photosynthetic efficiency. The genetic mechanism controlling PD formation in C3 and C4 leaves is largely unknown, especially in monocot crops, due to the technical challenge of quantifying these nanostructures with electron microscopy. To address this issue, we have generated stably transformed lines of Oryza sativa (rice, C3) and Setaria viridis (setaria, C4) with fluorescent protein-tagged PD to build the first spatiotemporal atlas of leaf pit field (cluster of PD) density in monocots without the need for electron microscopy. Across leaf development, setaria had consistently more PD connections at the M-BS wall interface than rice while the difference in M-M pit field density varied. While light was a critical trigger of PD formation, cell type and function determined leaf pit field density. Complementary temporal mRNA sequencing and gene co-expression network analysis revealed that the pattern of pit field density correlated with differentially expressed PD-associated genes and photosynthesis-related genes. PD-associated genes identified from our co-expression network analysis are related to cell wall expansion, translation and chloroplast signalling.
[学术文献 ] Convergence and divergence of diploid and tetraploid cotton genomes 进入全文
NATURE GENETICS
Polyploidy is an important driving force in speciation and evolution; however, the genomic basis for parallel selection of a particular trait between polyploids and ancestral diploids remains unexplored. Here we construct graph-based pan-genomes for diploid (A2) and allotetraploid (AD1) cotton species, enabled by an assembly of 50 genomes of genetically diverse accessions. We delineate a mosaic genome map of tetraploid cultivars that illustrates genomic contributions from semi-wild forms into modern cultivars. Pan-genome comparisons identify syntenic and hyper-divergent regions of continued variation between diploid and tetraploid cottons, and suggest an ongoing process of sequence evolution potentially linked to the contrasting genome size change in two subgenomes. We highlight 43% of genetic regulatory relationships for gene expression in diploid encompassing sequence divergence after polyploidy, and specifically characterize six underexplored convergent genetic loci contributing to parallel selection of fiber quality. This study offers a framework for pan-genomic dissection of genetic regulatory components underlying parallel selection of desirable traits in organisms. High-quality assemblies of 15 diploid and 35 allotetraploid cotton accessions are analyzed in graph-based pan-genomes, providing insights into genome dynamics and regulatory control of fiber transcriptomes under varying ploidy and selection pressures.
[学术文献 ] Membrane Interactions of GET1 and GET2 Facilitate Fiber Cell Initiation through the Guided Entry of the TA Protein Pathway in Cotton 进入全文
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
The guided entry of TA proteins (GET) pathway, which is responsible for the post-translational targeting and insertion of the tail-anchored (TA) protein into the endoplasmic reticulum (ER), plays an important role in physiological processes such as protein sorting, vesicle trafficking, cell apoptosis, and enzymatic reactions in which the GET1/2 complex is indispensable. However, a comprehensive study of the GET1 and GET2 genes and the GET pathway in cotton has not yet been carried out. Here, 12 GET1 and 21 GET2 genes were identified in nine representative plant species, and the phylogenetic relationships, gene structures, protein motifs, cis-regulatory elements (CREs), and temporal and spatial expression profiles were analyzed thoroughly. Our study indicated that GhGET1s and GhGET2s might be localized on ER membranes. According to expression profiling and CREs analysis, GhGET2-A02 was identified as a promising candidate for fiber cell development, interacting with two GhGET1s in the membrane, with a binding bias toward GhGET1-A06. Silencing of GhGET1-A06 or GhGET2-A02 reduced fiber initiation and elongation. In summary, our research provides important evidence for understanding the gene families and functions of GET1 and GET2 in cotton and provides clues for molecular breeding of high-quality cotton fiber varieties.
[前沿资讯 ] Breeding, digitalization boost Xinjiang's cotton output, quality 进入全文
CGTN
The breeding of superior cotton varieties, along with digitalization and mechanization in cotton cultivation, has significantly boosted cotton output and quality in northwest China's Xinjiang Uygur Autonomous Region. A major cotton production area in the country, Xinjiang supplies exceptional raw materials for the textile and apparel industry. On October 9, Li Xueyuan, chief expert of Xinjiang's technological system for the cotton industry, announced that the per-unit output at a high-yield cotton demonstration field in Jinghe County, Bortala Mongolian Autonomous Prefecture, has set a national record for calculated yield over a large harvest area. Since superior varieties are crucial for achieving high cotton yields, Li and his team have independently developed over 20 high-quality cotton varieties in recent years to boost yields in Xinjiang. "Initially, our goal in breeding new varieties focused solely on increasing cotton yields. Later, we expanded our objectives to achieve early maturity, premium quality, disease resistance, and suitability for mechanical harvesting. Now, most of these objectives have been achieved," Li said. In addition to cotton breeding efforts, the Xinjiang Department of Agriculture and Rural Affairs has established a technology system for cotton production, with the chief expert bearing ultimate responsibility. Demonstration fields have been set up in major cotton-growing counties to promote balanced growth in cotton production across the region. Now, digital farming supports cotton farmers in the meticulous management of their fields. For instance, field practices such as watering and fertilization can be controlled via mobile phone. "You see, the cotton crops we grow have robust stalks and abundant bolls. It's easy for one person to manage nearly 500 mu (about 33.3 hectares) of land," said Dong Chenglong, a cotton farmer in Jinghe County. Mechanized harvesting further eases Dong's work. A cotton picker can harvest an average of 500 mu of cotton per day, equivalent to the work of 2,000 laborers. "In the past, cotton scattered on the ground would become contaminated upon contact with soil. Now, with the cotton being baled by the cotton picker, contamination is eliminated. We use loaders and forklifts, making transportation simple with just one lift. This method also ensures high cotton quality," Dong said. This year, the mechanization rate for cotton plowing, planting, and harvesting in Xinjiang has reached 97 percent. In China, 90 percent of the cotton is used in the textile and apparel industry. Xinjiang's long-staple cotton, known for its long fibers, softness, and absorbency, is an excellent raw material for high-end textile products. "When we simulate sweating in the lining, there's no visible sweat stain from the outside. This solves the issue of sweat stains for people who wear shirts in summer. It's similar to coating the cotton with a membrane, and since we use long-staple cotton from Xinjiang, the fabric's breathability is excellent," said Cai Wei, general manager of a clothing brand in Xinjiang. Xinjiang's total cotton output has remained steady at over 5 million tonnes for five consecutive years, with its planting area and total production ranking first in China for 30 consecutive years.
[学术文献 ] Daily glycome and transcriptome profiling reveals polysaccharide structures and correlated glycosyltransferases critical for cotton fiber growth 进入全文
PLANT JOURNAL
Cotton fiber is the most valuable naturally available material for the textile industry and the fiber length and strength are key determinants of its quality. Dynamic changes in the pectin, xyloglucan, xylan, and cellulose polysaccharide epitope content during fiber growth contribute to complex remodeling of fiber cell wall (CW) and quality. Detailed knowledge about polysaccharide compositional and structural alteration in the fiber during fiber elongation and strengthening is important to understand the molecular dynamics of fiber development and improve its quality. Here, large-scale glycome profiling coupled with fiber phenotype and transcriptome profiling was conducted on fiber collected daily covering the most critical window of fiber development. The profiling studies with high temporal resolution allowed us to identify specific polysaccharide epitopes associated with distinct fiber phenotypes that might contribute to fiber quality. This study revealed the critical role of highly branched RG-I pectin epitopes such as beta-1,4-linked-galactans, beta-1,6-linked-galactans, and arabinogalactans, in addition to earlier reported homogalacturonans and xyloglucans in the formation of cotton fiber middle lamella and contributing to fiber plasticity and elongation. We also propose the essential role of heteroxylans (Xyl-MeGlcA and Xyl-3Ar), as a guiding factor for secondary CW cellulose microfibril arrangement, thus contributing to fiber strength. Correlation analysis of profiles of polysaccharide epitopes from glycome data and expression profiles of glycosyltransferase-encoding genes from transcriptome data identified several key putative glycosyltransferases that are potentially involved in synthesizing the critical polysaccharide epitopes. The findings of this study provide a foundation to identify molecular factors that dictate important fiber traits.
[前沿资讯 ] 浙江大学棉花团队揭示棉花苞叶发育新机制 进入全文
科学网
棉花通常具有三片苞叶，位于蕾铃外部，具有保护花和种子免受外界不良环境的影响以及承担一部分的光合作用。窄卷苞叶是棉花苞叶突变体的一种，于1945年在美国阿堪萨斯州的一个农场被发现。窄卷苞叶突变体苞叶长而狭窄，与蕾铃贴合不紧密，是棉花育种上一个重要的抗虫性状和机采性状。该突变体发现距今已有半个世纪之久，但调控该性状的基因却没有被克隆。 近日，浙江大学棉花精准育种团队在国际知名期刊Advanced Science杂志发表了题为“A CC-NB-ARC-LRR Gene Regulates Bract Morphology in Cotton”的研究论文。该研究克隆了棉花窄卷苞叶基因，解析了苞叶发育的分子机制。 该研究通过TM-1和T582的F2作图群体成功克隆窄卷苞叶基因（fg），并利用病毒诱导基因沉默技术（Virus-induced genes silencing, VIGS）、基因编辑技术（CRISPR/Cas9）、RNA干扰技术（RNA interference, RNAi）、单细胞转录组技术等进行了基因功能验证及作用机制解析，并初步提出了一个关于窄卷苞叶和正常苞叶形成的模式。该研究也为进一步研究苞叶形态建成的分子调控机制奠定了重要的研究基础。 此外，利用该研究中开发的分子标记进行辅助选择，将窄卷苞叶表型导入到新疆零式果枝长绒棉品种中，培育出一个新型的窄卷苞叶型长绒棉新品系Gb.CB。该材料可在一定程度上解决长绒棉机采过程中由苞叶导致的纤维含杂率过高的问题，欢迎育种单位合作开发利用。 该论文的第一作者是现代种业所博士生严孙艺、新农院副研究员司占峰、博士生齐国安，胡艳教授为论文的通讯作者。张天真教授为本研究提供了诸多建议和帮助。博士后玄丽莎，在读博士研究生何璐、李笑然，已毕业博士研究生曹译文参与了部分研究。该研究受到农业生物育种重大项目的支持。
