National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, PR China.
Institute of Economic Crops, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, PR China.
J Exp Bot. 2019 Mar 11;70(5):1525-1538. doi: 10.1093/jxb/erz036.
Abscission is a process that allows plants to shed tissues or organs via cell separation, and occurs throughout the life cycle. Removal of leaves through the use of chemical defoliants is very important for mechanical harvesting of cotton (Gossypium hirsutum). However, our knowledge of the molecular mechanisms of the defoliation response involved is limited. In this study, RNA-seq was conducted in order to profile the differentially expressed genes (DEGs) between cultivars X50 (sensitive to chemical defoliants) and X33 (relatively insensitive) at different time points after treatment with thidiazuron and ethephon (TE). A total of 2434 DEGs were identified between the two cultivars across the different time-points. Functional categories according to GO and KEGG analyses revealed that plant hormone signal transduction and zeatin biosynthesis were involved in the response to TE. Cytokinin oxidase/dehydrogenase (CKX) genes and ethylene-related genes were up-regulated following TE treatment, and were associated with increased level of ethylene, especially in cultivar X50. Down-regulation of GhCKX3 resulted in delayed defoliation and a reduced ethylene response. The results show that crosstalk between cytokinin and ethylene regulates cotton defoliation, and provide new insights into the molecular mechanisms underlying the mode of action of defoliants in cotton.
脱落是一种通过细胞分离使植物组织或器官脱落的过程，发生在整个生命周期中。使用化学脱叶剂去除叶片对于棉花（Gossypium hirsutum）的机械收获非常重要。然而，我们对涉及的脱叶反应的分子机制的了解是有限的。在这项研究中，进行了 RNA-seq 分析，以描绘在使用噻二唑隆和乙烯利（TE）处理后不同时间点的敏感品种 X50 和相对不敏感品种 X33 之间的差异表达基因（DEGs）。在不同时间点，两个品种之间共鉴定出 2434 个 DEGs。GO 和 KEGG 分析的功能类别表明，植物激素信号转导和玉米素生物合成参与了对 TE 的反应。细胞分裂素氧化酶/脱氢酶（CKX）基因和乙烯相关基因在 TE 处理后上调，并与乙烯水平的升高有关，特别是在品种 X50 中。GhCKX3 的下调导致脱叶延迟和乙烯反应降低。结果表明，细胞分裂素和乙烯之间的相互作用调节棉花脱叶，并为脱叶剂在棉花中的作用模式的分子机制提供了新的见解。
