Zeng Jianyan, Xi Jing, Li Baoxia, Yan Xingying, Dai Yonglu, Wu Yiping, Xiao Yuehua, Pei Yan, Zhang Mi
Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China.
Academy of Agricultural Sciences, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China.
Plant Cell Rep. 2022 Apr;41(4):1059-1073. doi: 10.1007/s00299-022-02837-2. Epub 2022 Feb 26.
Dynamic organization of actin and microtubule cytoskeletons directs a distinct expansion behavior of cotton fiber initiation from cell elongation. Cotton fibers are highly elongated single cells derived from the ovule epidermis. Although actin and microtubule (MT) cytoskeletons have been implicated in cell elongation and secondary wall deposition, their roles in fiber initiation is poorly understood. Here, we used fluorescent probes and pharmacological approaches to study the roles of these cytoskeletal components during cotton fiber initiation. Both cytoskeletons align along the growth axis in initiating fibers. The dorsal view of ovules shows that unlike the fine actin filaments (AFs) in nonfiber cells, the AFs in fiber cells are dense and bundled. MTs are randomized in fiber cells and well-ordered in nonfiber cells. The pharmacological experiments revealed that the depolymerization of AFs and MTs assisted fiber initiation. Both AF stabilization and depolymerization inhibited fiber elongation. In contrast, the proper depolymerization of MTs promoted cell elongation, although the MT-stabilizing drug consistently resulted in a negative effect. Notably, we found that the organization of AFs was correlated with MT dynamics. Stabilizing the MTs by taxol treatment promoted the formation of AF bundles (in fiber initials) and transversely aligned AFs (in elongating fibers), whereas depolymerizing the MTs by oryzalin treatment promoted the fragmentation of AFs. Collectively, our data indicates that MTs plays a crucial role in regulating AF organization and early development of cotton fibers.
肌动蛋白和微管细胞骨架的动态组织引导棉花纤维起始阶段从细胞伸长开始的独特扩展行为。棉花纤维是源自胚珠表皮的高度伸长的单细胞。尽管肌动蛋白和微管（MT）细胞骨架与细胞伸长和次生壁沉积有关，但其在纤维起始阶段的作用却知之甚少。在此，我们使用荧光探针和药理学方法来研究这些细胞骨架成分在棉花纤维起始阶段的作用。在起始纤维中，两种细胞骨架均沿生长轴排列。胚珠的背面视图显示，与非纤维细胞中的细肌动蛋白丝（AFs）不同，纤维细胞中的AFs密集且成束。MTs在纤维细胞中随机分布，而在非纤维细胞中排列有序。药理学实验表明，AFs和MTs的解聚有助于纤维起始。AFs的稳定和去聚合均抑制纤维伸长。相反，MTs的适当解聚促进细胞伸长，尽管MT稳定药物始终产生负面影响。值得注意的是，我们发现AFs的组织与MT动态相关。通过紫杉醇处理稳定MTs促进了AF束（在纤维起始细胞中）和横向排列的AFs（在伸长纤维中）的形成，而通过氨磺乐灵处理使MTs解聚则促进了AFs的断裂。总体而言，我们的数据表明MTs在调节AF组织和棉花纤维早期发育中起关键作用。
