Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China.
Plant Cell. 2021 Aug 31;33(8):2736-2752. doi: 10.1093/plcell/koab153.
Cotton, one of the most important crops in the world, produces natural fiber materials for the textile industry. WRKY transcription factors play important roles in plant development and stress responses. However, little is known about whether and how WRKY transcription factors regulate fiber development of cotton so far. In this study, we show that a fiber-preferential WRKY transcription factor, GhWRKY16, positively regulates fiber initiation and elongation. GhWRKY16-silenced transgenic cotton displayed a remarkably reduced number of fiber protrusions on the ovule and shorter fibers compared to the wild-type. During early fiber development, GhWRKY16 directly binds to the promoters of GhHOX3, GhMYB109, GhCesA6D-D11, and GhMYB25 to induce their expression, thereby promoting fiber initiation and elongation. Moreover, GhWRKY16 is phosphorylated by the mitogen-activated protein kinase GhMPK3-1 at residues T-130 and S-260. Phosphorylated GhWRKY16 directly activates the transcription of GhMYB25, GhHOX3, GhMYB109, and GhCesA6D-D11 for early fiber development. Thus, our data demonstrate that GhWRKY16 plays a crucial role in fiber initiation and elongation, and that GhWRKY16 phosphorylation by GhMPK3-1 is essential for the transcriptional activation on downstream genes during the fiber development of cotton.
棉花是世界上最重要的作物之一，为纺织业生产天然纤维材料。WRKY 转录因子在植物发育和应激反应中发挥重要作用。然而，迄今为止，人们对于 WRKY 转录因子是否以及如何调节棉花纤维发育知之甚少。在本研究中，我们发现一个纤维偏好性的 WRKY 转录因子 GhWRKY16 正向调控纤维起始和伸长。GhWRKY16 沉默的转基因棉花与野生型相比，胚珠上的纤维突起数量明显减少，纤维变短。在早期纤维发育过程中，GhWRKY16 直接结合到 GhHOX3、GhMYB109、GhCesA6D-D11 和 GhMYB25 的启动子上，诱导它们的表达，从而促进纤维起始和伸长。此外，GhWRKY16 在丝裂原活化蛋白激酶 GhMPK3-1 的残基 T-130 和 S-260 处被磷酸化。磷酸化的 GhWRKY16 直接激活 GhMYB25、GhHOX3、GhMYB109 和 GhCesA6D-D11 的转录，从而促进早期纤维发育。因此，我们的数据表明 GhWRKY16 在纤维起始和伸长中起关键作用，并且 GhWRKY16 由 GhMPK3-1 磷酸化对于棉花纤维发育过程中下游基因的转录激活是必不可少的。
