CYP74B24 is the 13-hydroperoxide lyase involved in biosynthesis of green leaf volatiles in tea (Camellia sinensis)
CYP74B24 is the 13-hydroperoxide lyase involved in biosynthesis of green leaf volatiles in tea (Camellia sinensis)
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DOI：
10.1016/j.plaphy.2015.11.016
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发表时间：
2016-01-01
影响因子：
6.5
通讯作者：
Matsui, Kenji
中科院分区：
文献类型：
--
作者：
Ono, Eiichiro;Handa, Taiki;Matsui, Kenji
绿色叶挥发物（GLVs）是C6-脂肪醛/醇/乙酸酯，在多种植物中由中心前体脂肪酸13-氢过氧化物通过13-氢过氧化物裂解酶（HPLs）生物合成。虽然GLV被认为是植物中的防御化合物，但GLV在由茶树嫩叶制成的绿色茶中为一束香气提供了特征性的草香。在此，我们从C.通过RNA测序（RNA-Seq）技术对茶树HPL基因进行了克隆和功能分析，并对候选基因CYP 74 B24进行了功能鉴定。在大肠杆菌中异源表达的重组CYP 74 B24蛋白在体外以13-HPOT为底物特异性地产生（Z）-3-己烯醛，最适pH为6.0。CYP 74 B24基因在整个地上器官中以组成型的方式表达，并被机械损伤进一步诱导。CYP 74 B24基因在完整茶叶中的组成型表达可能解释了低但大量的组成型形成的GLV子集，其中一些以糖苷形式储存。我们的研究结果不仅为GLV在茶树中发挥的生物学作用提供了新的见解，而且还为茶叶制造过程中香气品质的改善提供了依据。(C)2015年Elsevier Masson SAS。All rights reserved.
Green leaf volatiles (GLVs) are C6-aliphatic aldehydes/alcohols/acetates, and biosynthesized from the central precursor fatty acid 13-hydroperoxides by 13-hydroperoxide lyases (HPLs) in various plant species. While GLVs have been implicated as defense compounds in plants, GLVs give characteristic grassy note to a bouquet of aroma in green tea, which is manufactured from young leaves of Camellia sinensis. Here we identify three HPL-related genes from C. sinensis via RNA-Sequencing (RNA-Seq) in silico, and functionally characterized a candidate gene, CYP74B24, as a gene encoding tea HPL. Recombinant CYP74B24 protein heterologously expressed in Escherichia coli specifically produced (Z)-3-hexenal from 13-HPOT with the optimal pH 6.0 in vitro. CYP74B24 gene was expressed throughout the aerial organs in a rather constitutive manner and further induced by mechanical wounding. Constitutive expression of CYP74B24 gene in intact tea leaves might account for low but substantial and constitutive formation of a subset of GLVs, some of which are stored as glycosides. Our results not only provide novel insights into the biological roles that GLVs play in tea plants, but also serve as basis for the improvement of aroma quality in tea manufacturing processes. (C) 2015 Elsevier Masson SAS. All rights reserved.