State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China.
Collaborative Innovation Center of Henan Grain Crops, Agronomy College, Henan Agricultural University, Zhengzhou, China.
J Exp Bot. 2022 Jan 27;73(3):711-726. doi: 10.1093/jxb/erab451.
In plants, glucose (Glc) plays important roles, as a nutrient and signal molecule, in the regulation of growth and development. However, the function of Glc in fiber development of upland cotton (Gossypium hirsutum) is unclear. Here, using gas chromatography-mass spectrometry (GC-MS), we found that the Glc content in fibers was higher than that in ovules during the fiber elongation stage. In vitro ovule culture revealed that lower Glc concentrations promoted cotton fiber elongation, while higher concentrations had inhibitory effects. The hexokinase inhibitor N-acetylglucosamine (NAG) inhibited cotton fiber elongation in the cultured ovules, indicating that Glc-mediated fiber elongation depends on the Glc signal transduced by hexokinase. RNA sequencing (RNA-seq) analysis and hormone content detection showed that 150mM Glc significantly activated brassinosteroid (BR) biosynthesis, and the expression of signaling-related genes was also increased, which promoted fiber elongation. In vitro ovule culture clarified that BR induced cotton fiber elongation in a dose-dependent manner. In hormone recovery experiments, only BR compensated for the inhibitory effects of NAG on fiber elongation in a Glc-containing medium. However, the ovules cultured with the BR biosynthetic inhibitor brassinazole and from the BR-deficient cotton mutant pag1 had greatly reduced fiber elongation at all the Glc concentrations tested. This demonstrates that Glc does not compensate for the inhibition of fiber elongation caused by BR biosynthetic defects, suggesting that the BR signaling pathway works downstream of Glc during cotton fiber elongation. Altogether, our study showed that Glc plays an important role in cotton fibre elongation, and crosstalk occurs between Glc and BR signaling during modulation of fiber elongation.
在植物中，葡萄糖（Glc）作为一种营养物质和信号分子，在调节生长和发育方面发挥着重要作用。然而，Glc 在陆地棉（Gossypium hirsutum）纤维发育中的功能尚不清楚。在这里，我们使用气相色谱-质谱联用（GC-MS）发现，在纤维伸长阶段，纤维中的 Glc 含量高于胚珠。体外胚珠培养表明，较低的 Glc 浓度促进棉花纤维伸长，而较高的浓度则具有抑制作用。己糖激酶抑制剂 N-乙酰葡萄糖胺（NAG）抑制培养胚珠中的棉花纤维伸长，表明 Glc 介导的纤维伸长依赖于己糖激酶传递的 Glc 信号。RNA 测序（RNA-seq）分析和激素含量检测表明，150mM Glc 显著激活了油菜素内酯（BR）的生物合成，并且信号相关基因的表达也增加，从而促进了纤维伸长。体外胚珠培养澄清，BR 以剂量依赖的方式诱导棉花纤维伸长。在激素恢复实验中，只有 BR 在含 Glc 的培养基中补偿了 NAG 对纤维伸长的抑制作用。然而，在所有测试的 Glc 浓度下，用 BR 生物合成抑制剂油菜素唑和 BR 缺陷型棉花突变体 pag1 培养的胚珠，其纤维伸长大大减少。这表明 Glc 不能补偿 BR 生物合成缺陷对纤维伸长的抑制作用，这表明 BR 信号通路在棉花纤维伸长过程中位于 Glc 信号的下游。总之，我们的研究表明，Glc 在棉花纤维伸长中起重要作用，并且在调节纤维伸长过程中，Glc 和 BR 信号之间存在串扰。
