Background

Cotton is the source of natural fibers globally, fulfilling 90% of the textile industry's requirements. However, fiber development is a complex biological process comprising four stages. Fiber develops from a single cell, and cell elongation is a vital process in fiber development. Therefore, it is pertinent to understand and exploit mechanisms underlying cell elongation during fiber development. A previous report about cell division control protein 42 (CDC-42) with its key role in cell elongation in eukaryotes inspired us to explore its homologs Rho GTPases for understanding of cell elongation during cotton fiber development.

Result

We classified 2 066 Rho proteins from 8 Gossypium species into 5 and 8 groups within A and D sub-genomes, respectively. Asymmetric evolution of Rho members was observed among five tetraploids. Population fixation statistics between two short and long fiber genotypes identified highly diverged regions encompassing 34 Rho genes in G. hirustum, and 31 of them were retained through further validation by genome wide association analysis (GWAS). Moreover, a weighted gene co-expression network characterized genome-wide expression patteren of Rho genes based on previously published transcriptome data. Twenty Rho genes from five modules were identified as hub genes which were potentially related to fiber development. Interaction networks of 5 Rho genes based on transcriptional abundance and gene ontology (GO) enrichment emphasized the involvement of Rho in cell wall biosynthesis, fatty acid elongation, and other biological processes.

Conclusion

Our study characterized the Rho proteins in cotton, provided insights into the cell elongation of cotton fiber and potential application in cotton fiber improvement.

中文翻译：

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棉花 Rho 家族的全基因组表征为纤维发育提供了见解

背景

棉花是全球天然纤维的来源，可满足纺织工业 90% 的需求。然而，纤维发育是一个复杂的生物过程，包括四个阶段。纤维由单个细胞发育而成，细胞伸长是纤维发育的重要过程。因此，了解和利用纤维发育过程中细胞伸长的机制是相关的。之前一篇关于细胞分裂控制蛋白 42 (CDC-42) 及其在真核生物细胞伸长中的关键作用的报告启发我们探索其同源物 Rho GTPases，以了解棉纤维发育过程中的细胞伸长。

结果

我们将来自 8 个棉属物种的2 066 个 Rho 蛋白分别分为 A 和 D 亚基因组内的 5 组和 8 组。在五个四倍体中观察到 Rho 成员的不对称进化。两种短纤维和长纤维基因型之间的群体固定统计数据确定了陆地棉中包含 34 个Rho基因的高度分化区域，其中 31 个通过全基因组关联分析 (GWAS) 的进一步验证被保留。此外，加权基因共表达网络根据先前发表的转录组数据表征了Rho基因的全基因组表达模式。来自五个模块的二十个Rho基因被鉴定为可能与纤维发育相关的中心基因。基于转录丰度和基因本体（GO）富集的 5 个Rho基因的相互作用网络强调了 Rho 参与细胞壁生物合成、脂肪酸延伸和其他生物过程。

结论

我们的研究表征了棉花中的 Rho 蛋白，为棉纤维的细胞伸长及其在棉纤维改良中的潜在应用提供了见解。