College of Biological Science and Agriculture, Qiannan Normal University for Nationalities, Duyun 558000, China.
South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou 510650, China.
J Agric Food Chem. 2022 Sep 28;70(38):11880-11891. doi: 10.1021/acs.jafc.2c01549. Epub 2022 Sep 15.
Polyamine oxidase (PAO) is a key enzyme maintaining polyamine homeostasis, which affects plant physiological activities. Until now, the gene members and function of PAOs in tea () have not been fully identified. Here, through the expression in and , we identified six genes annotated as in tea genome and transcriptome and determined their enzyme reaction modes and gene expression profiles in tea cultivar 'Yinghong 9'. We found that CsPAO1,2,3 could catalyze spermine, thermospermine, and norspermidine, and CsPAO2,3 could catalyze spermidine in the back-conversion mode, which indicated that the precursor of γ-aminobutyric acid might originate from the oxidation of putrescin but not spermidine. We further investigated the changes of CsPAO activity with temperature and pH and their stability. Kinetic parameters suggested that CsPAO2 was the major PAO modifying polyamine composition in tea, and it could be inactivated by β-hydroxyethylhydrazine and aminoguanidine. Putrescine content and expression were high in tea flowers. responded to wound, drought, and salt stress; might be the main member responding to cold stress; anoxia induced . We conclude that in terms of phylogenetic tree, enzyme characteristics, and expression profile, might be the dominant in the polyamine degradation pathway.
多胺氧化酶（PAO）是维持多胺稳态的关键酶，影响植物的生理活动。到目前为止，茶（）中 PAO 的基因成员和功能尚未完全确定。在这里，通过在 和 中的表达，我们在茶树基因组和转录组中鉴定了六个注释为 的基因，并确定了它们在茶树品种“迎红 9”中的酶反应模式和基因表达谱。我们发现 CsPAO1、2、3 可以催化精胺、热精胺和正亚精胺，而 CsPAO2、3 可以以反向转化模式催化亚精胺，这表明γ-氨基丁酸的前体可能来自腐胺的氧化，而不是亚精胺。我们进一步研究了 CsPAO 活性随温度和 pH 值的变化及其稳定性。动力学参数表明 CsPAO2 是主要的 PAO，可修饰茶叶中的多胺组成，其可被β-羟乙基肼和氨基胍失活。腐胺含量和 表达在茶花中较高。 对创伤、干旱和盐胁迫有反应； 可能是主要的冷胁迫响应成员；缺氧诱导 。我们的结论是，从系统发生树、酶特性和表达谱来看， 可能是多胺降解途径中的主要 。
