Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 310008, China; Key Laboratory of Tea Biology and Resource Utilization of Ministry of Agriculture, Hangzhou, 310008, China.
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 310008, China; Key Laboratory of Tea Biology and Resource Utilization of Ministry of Agriculture, Hangzhou, 310008, China.
Plant Physiol Biochem. 2019 Feb;135:132-140. doi: 10.1016/j.plaphy.2018.11.035. Epub 2018 Dec 1.
The biosynthesis of jasmonic acid (JA) in plant peroxisomes requires the action of acyl-CoA oxidase (ACX; EC 1.3.3.6). Multiple isoforms of ACXs have been identified in various annual herbaceous plants, but the genes encoding these enzymes in perennial woody plants are yet to be fully investigated. In this study, an ACX gene named CsACX1 (GeneBank accession: KX650077.1) was isolated from tea plant (Camellia sinensis L.). CsACX1 was predicted to consist of 664 amino acid residues. Transcriptional analysis revealed that CsACX1 can be induced by mechanical wounding, JA application, and infestation by the tea geometrid Ectropis obliqua Prout and the tea green leafhopper Empoasca (Matsumurasca) onukii Matsuda. To further elucidate the function of CsACX1, it was heterologously expressed in a bacterial system and characterized. Recombinant CsACX1 showed preference for C ∼ C-CoA substrates. The constitutive expression of CsACX1 can rescue wound-related JA biosynthesis in Arabidopsis mutant acx1. CsACX1 was expressed in different organs, predominantly in flowers. Notably, CsACX1 transcripts were detected up-regulated during flower opening, and the JA levels were correlated with CsACX1 expression. All these results enrich our knowledge of the regulatory pathway involved in the JA biosynthesis in tea, and helps further understand the defense mechanism of tea plant against insects.
植物过氧化物酶体中茉莉酸（JA）的生物合成需要酰基辅酶 A 氧化酶（ACX；EC 1.3.3.6）的作用。在各种一年生草本植物中已经鉴定出多种 ACX 同工酶，但多年生木本植物中这些酶的编码基因尚未得到充分研究。本研究从茶树（Camellia sinensis L.）中分离出一个 ACX 基因，命名为 CsACX1（GeneBank 登录号：KX650077.1）。CsACX1 预测由 664 个氨基酸残基组成。转录分析表明，CsACX1 可以被机械损伤、JA 处理以及茶尺蠖 Ectropis obliqua Prout 和茶绿叶蝉 Empoasca（Matsumurasca）onukii Matsuda 的侵害诱导。为了进一步阐明 CsACX1 的功能，将其在细菌系统中异源表达并进行了表征。重组 CsACX1 对 C ∼ C-CoA 底物表现出偏好。CsACX1 的组成型表达可以挽救拟南芥突变体 acx1 中与伤口相关的 JA 生物合成。CsACX1 在不同的器官中表达，主要在花中表达。值得注意的是，在花朵开放过程中检测到 CsACX1 转录本上调，JA 水平与 CsACX1 表达相关。所有这些结果丰富了我们对茶树中 JA 生物合成调控途径的认识，并有助于进一步了解茶树对昆虫的防御机制。
