Glucosylation of the phytoalexin N-feruloyl tyramine modulates the levels of pathogen-responsive metabolites in Nicotiana benthamiana.
Glucosylation of the phytoalexin N-feruloyl tyramine modulates the levels of pathogen-responsive metabolites in Nicotiana benthamiana.
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DOI：
10.1111/tpj.14420
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发表时间：
2019-10
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通讯作者：
Guangxin Sun;M. Strebl;M. Merz;Robert Blamberg;F. Huang;Kate McGraphery;T. Hoffmann;W. Schwab-
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文献类型：
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作者：
Guangxin Sun;M. Strebl;M. Merz;Robert Blamberg;F. Huang;Kate McGraphery;T. Hoffmann;W. Schwab-
酶的混杂性是许多转化小分子的尿苷二磷酸糖依赖性糖基转移酶 (UGT) 的共同特性，它显着阻碍了天然底物的识别，从而阻碍了酶生理作用的表征。在这里，我们提出了一种简单但有效的策略，使用 LC-MS 引导的转基因植物靶向糖苷分析来鉴定植物 UGT 的内源底物。我们成功地鉴定了两种混杂的本塞姆氏烟草 UGT（NbUGT73A24 和 NbUGT73A25）的天然底物，它们是来自烟草的病原体诱导的烟草 UGT (TOGT) 的直系同源物，参与过敏反应。而在烟草中，TOGT 葡萄糖基化的东莨菪碱经水杨酸盐、真菌诱导子和烟草花叶病毒处理后，NbUGT73A24 和 NbUGT73A25 产生植物抗毒素 N-阿魏酰酪胺的糖苷，可以增强细胞壁以防止病原体的侵入，并在农杆菌渗透后产生黄酮醇 本塞姆氏烟草中的相应基因。生理糖苷配基文库部分的酶促糖基化证实了 UGT 的生物底物。此外，本塞姆氏烟草中这两个基因的过度表达会在叶子上产生明显的损伤，并导致病原体诱导的植物代谢物（例如苯丙氨酸和色氨酸）的含量显着降低。我们的结果揭示了 TOGT 酶的其他生物学功能，并表明 UGT 在植物抗性中的多功能作用。本文受版权保护。版权所有。
Enzyme promiscuity, a common property of many uridine-diphosphate sugar-dependent glycosyltransferases (UGTs) that convert small molecules, significantly hinders the identification of natural substrates and thus the characterization of the physiological role of enzymes. Here we present a simple but effective strategy to identify endogenous substrates of plant UGTs using LC-MS-guided targeted glycoside analysis of transgenic plants. We successfully identified natural substrates of two promiscuous Nicotiana benthamiana UGTs (NbUGT73A24 and NbUGT73A25), orthologues of pathogen-induced tobacco UGT (TOGT) from N. tabacum, which is involved in the hypersensitive reaction. While in N. tabacum, TOGT glucosylated scopoletin after treatment with salicylate, fungal elicitors and the tobacco mosaic virus, NbUGT73A24 and NbUGT73A25 produced glucosides of phytoalexin N-feruloyl tyramine, which may strengthen cell walls to prevent the intrusion of pathogens, and flavonols after agroinfiltration of the corresponding genes in N. benthamiana. Enzymatic glucosylation of fractions of a physiological aglycone library confirmed the biological substrates of UGTs. In addition, overexpression of both genes in N. benthamiana produced clear lesions on the leaves and led to a significantly reduced content of pathogen-induced plant metabolites such as phenylalanine and tryptophan. Our results revealed additional biological functions of TOGT enzymes and indicate a multifunctional role of UGTs in plant resistance. This article is protected by copyright. All rights reserved.