Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
Plant J. 2022 Aug;111(3):785-799. doi: 10.1111/tpj.15852. Epub 2022 Jun 18.
The BRASSINAZOLE-RESISTANT (BZR) transcription factor is a core component of brassinosteroid (BR) signaling and is involved in the development of many plant species. BR is essential for the initiation and elongation of cotton fibers. However, the mechanism of BR-regulating fiber development and the function of BZR is poorly understood in Gossypium hirsutum L. (cotton). Here, we identified a BZR family transcription factor protein referred to as GhBZR3 in cotton. Overexpression of GhBZR3 in Arabidopsis caused shorter root hair length, hypocotyl length, and hypocotyl cell length, indicating that GhBZR3 negatively regulates cell elongation. Pathway enrichment analysis from VIGS-GhBZR3 cotton plants found that fatty acid metabolism and degradation might be the regulatory pathway that is primarily controlled by GhBZR3. Silencing GhBZR3 expression in cotton resulted in taller plant height as well as longer fibers. The very-long-chain fatty acid (VLCFA) content was also significantly increased in silenced GhBZR3 plants compared with the wild type. The GhKCS13 promoter, a key gene for VLCFA biosynthesis, contains two GhBZR3 binding sites. The results of yeast one-hybrid, electrophoretic mobility shift, and luciferase assays revealed that GhBZR3 directly interacted with the GhKCS13 promoter to suppress gene expression. Taken together, these results indicate that GhBZR3 negatively regulates cotton fiber development by reducing VLCFA biosynthesis. This study not only deepens our understanding of GhBZR3 function in cotton fiber development, but also highlights the potential of improving cotton fiber length and plant growth using GhBZR3 and its related genes in future cotton breeding programs.
BRASSINAZOLE-RESISTANT（BZR）转录因子是油菜素内酯（BR）信号的核心组成部分，参与许多植物物种的发育。BR 对于棉花纤维的起始和伸长是必不可少的。然而，BR 调节纤维发育的机制和 BZR 的功能在陆地棉（Gossypium hirsutum L.）中知之甚少。在这里，我们鉴定了一个 BZR 家族转录因子蛋白，在棉花中称为 GhBZR3。在拟南芥中过表达 GhBZR3 导致根毛长度、下胚轴长度和下胚轴细胞长度变短，表明 GhBZR3 负调控细胞伸长。VIGS-GhBZR3 棉花植株的途径富集分析发现，脂肪酸代谢和降解可能是 GhBZR3 主要调控的调节途径。沉默 GhBZR3 在棉花中的表达导致植株更高，纤维更长。沉默 GhBZR3 表达的棉花中非常长链脂肪酸（VLCFA）含量也明显高于野生型。VLCFA 生物合成的关键基因 GhKCS13 启动子含有两个 GhBZR3 结合位点。酵母单杂交、电泳迁移率变动分析和荧光素酶测定的结果表明，GhBZR3 直接与 GhKCS13 启动子相互作用，抑制基因表达。总之，这些结果表明，GhBZR3 通过减少 VLCFA 生物合成来负调控棉花纤维发育。本研究不仅加深了我们对 GhBZR3 在棉花纤维发育中的功能的理解，而且还突出了在未来棉花育种计划中利用 GhBZR3 及其相关基因来提高棉花纤维长度和植物生长的潜力。
