The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, School of Agriculture and Food Science, Zhejiang A&F University, Lin'an, Hangzhou 311300, Zhejiang, China.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430000, Hubei, China.
Int J Mol Sci. 2021 Mar 16;22(6):3000. doi: 10.3390/ijms22063000.
Dynamic remodeling of the actin cytoskeleton plays a central role in the elongation of cotton fibers, which are the most important natural fibers in the global textile industry. Here, a high-resolution mapping approach combined with comparative sequencing and a transgenic method revealed that a G65V substitution in the cotton actin Gh_D04G0865 (GhACT17D in the wild-type) is responsible for the Ligon lintless-1 () mutant (GhACT17DM). In the mutant GhACT17DM from plant, Gly65 is substituted with valine on the lip of the nucleotide-binding domain of GhACT17D, which probably affects the polymerization of F-actin. Over-expression of , but not , driven by either a CaMV35 promoter or a fiber-specific promoter in cotton produced a -like phenotype. Compared with the wild-type control, actin filaments in fibers showed higher growth and shrinkage rates, decreased filament skewness and parallelness, and increased filament density. Taken together, our results indicate that the incorporation of GhACT17DM during actin polymerization disrupts the establishment and dynamics of the actin cytoskeleton, resulting in defective fiber elongation and the overall dwarf and twisted phenotype of the mutant.
肌动蛋白细胞骨架的动态重塑在棉花纤维的伸长中起着核心作用，棉花纤维是全球纺织工业中最重要的天然纤维。在这里，一种高分辨率作图方法结合比较测序和转基因方法表明，棉肌动蛋白 Gh_D04G0865（野生型中的 GhACT17D）中的 G65V 取代是 Ligon lintless-1()突变体（GhACT17DM）的原因。在突变体 GhACT17DM 中，植物 GhACT17D 的核苷酸结合域的脂面上甘氨酸 65 被缬氨酸取代，这可能影响 F-肌动蛋白的聚合。在棉花中，由 CaMV35 启动子或纤维特异性启动子驱动的 表达，产生了类似的表型。与野生型对照相比，纤维中的肌动蛋白丝表现出更高的生长和收缩率、降低的丝倾斜度和平行度以及增加的丝密度。总之，我们的结果表明，GhACT17DM 在肌动蛋白聚合过程中的掺入破坏了肌动蛋白细胞骨架的建立和动态，导致纤维伸长缺陷和突变体的整体矮化和扭曲表型。
