Wang Li, Mu Chun, Du Mingwei, Chen Yin, Tian Xiaoli, Zhang Mingcai, Li Zhaohu
State Key Laboratory of Plant Physiology and Biochemistry, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; College of Life Sciences, Henan Normal University, Xinxiang, Henan 453007, China.
State Key Laboratory of Plant Physiology and Biochemistry, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
Plant Sci. 2014 Aug;225:15-23. doi: 10.1016/j.plantsci.2014.05.005. Epub 2014 May 20.
The growth regulator mepiquat chloride (MC) is globally used in cotton (Gossypium hirsutum L.) canopy manipulation to avoid excess growth and yield loss. However, little information is available as to whether the modification of plant architecture by MC is related to alterations in gibberellic acid (GA) metabolism and signaling. Here, the role of GA metabolism and signaling was investigated in cotton seedlings treated with MC. The MC significantly decreased endogenous GA3 and GA4 levels in the elongating internode, which inhibited cell elongation by downregulating GhEXP and GhXTH2, and then reducing plant height. Biosynthetic and metabolic genes of GA were markedly suppressed within 2-10d of MC treatment, which also downregulated the expression of DELLA-like genes. A remarkable feedback regulation was observed at the early stage of MC treatment when GA biosynthetic and metabolic genes expression was evidently upregulated. Mepiquat chloride action was controlled by temporal translocation and spatial accumulation which regulated GA biosynthesis and signal expression for maintaining GA homeostasis. The results suggested that MC application could reduce endogenous GA levels in cotton through controlled GA biosynthetic and metabolic genes expression, which might inhibit cell elongation, thereby shortening the internode and reducing plant height.
生长调节剂甲哌鎓（MC）在全球范围内用于棉花（陆地棉）冠层调控，以避免过度生长和产量损失。然而，关于MC对植物形态的改变是否与赤霉素（GA）代谢和信号传导的变化有关，目前所知甚少。在此，研究了GA代谢和信号传导在经MC处理的棉花幼苗中的作用。MC显著降低了伸长节间内的内源GA3和GA4水平，通过下调GhEXP和GhXTH2抑制细胞伸长，进而降低株高。在MC处理的2-10天内，GA的生物合成和代谢基因受到显著抑制，这也下调了类DELLA基因的表达。在MC处理早期观察到明显的反馈调节，此时GA生物合成和代谢基因的表达明显上调。甲哌鎓的作用受时间转运和空间积累控制，其调节GA生物合成及信号表达以维持GA稳态。结果表明，施用MC可通过控制GA生物合成和代谢基因的表达降低棉花内源GA水平，这可能抑制细胞伸长，从而缩短节间并降低株高。
