Nicotinate O-Glucosylation Is an Evolutionarily Metabolic Trait Important for Seed Germination under Stress Conditions in Arabidopsis thaliana
Nicotinate O-Glucosylation Is an Evolutionarily Metabolic Trait Important for Seed Germination under Stress Conditions in Arabidopsis thaliana
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烟酸O-葡萄糖基化是拟南芥胁迫条件下种子萌发的重要进化代谢特征
DOI：
10.1105/tpc.15.00223
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发表时间：
2015-07-01
期刊：
影响因子：
11.6
通讯作者：
Wang, Guodong
中科院分区：
文献类型：
--
作者：
Li, Wei;Zhang, Fengxia;Wang, Guodong
烟酸（NA）是NAD补救途径的关键中间体，其糖基化广泛存在于陆生植物中。然而，NA糖基化的生理功能在植物中尚不清楚，迄今为止还没有编码NA糖基转移酶的基因的报道。拟南芥中NA糖基化发生在NA分子的N-或O-位置，并且O-葡糖基化似乎是拟南芥科所特有的。使用基因-酶的相关性集中在家庭1糖基转移酶（GT; EC 2.4），我们确定和表征三个拟南芥GT，这是可能参与NA糖基化。这些包括一种NAOGT（UGT 74 F2;先前鉴定为水杨酸糖基转移酶）和两种NANT（UGT 76 C4和UGT 76 C5）。拟南芥突变体UGT 74 F2积累更高水平的游离NA，但不水杨酸，比野生型，这与种子发芽率在各种非生物胁迫下呈负相关。UGT 74 F2 -1突变体的发芽缺陷可以通过UGT 74 F2的过表达得到完全补充。这些观察，再加上全面的化学分析，表明NA糖基化可能起到保护植物细胞的毒性NA过度积累在种子萌发过程中。结合系统发育分析，我们的研究结果表明，NAOGTs出现最近在菊科，并可能提供健身的好处。UGT 74 F2在拟南芥中的多功能性也进行了研究和讨论。
The glycosylation of nicotinate (NA), a key intermediate of the NAD salvage pathway, occurs widely in land plants. However, the physiological function of NA glycosylation is not well understood in planta, and no gene encoding NA glycosyltransferase has been reported to date. NA glycosylation in Arabidopsis thaliana occurs at either the N- or the O-position of the NA molecule, and O-glucosylation appears to be unique to the Brassicaceae. Using gene-enzyme correlations focused on Family 1 glycosyltransferases (GTs; EC 2.4), we identified and characterized three Arabidopsis GTs, which are likely involved in NA glycosylation. These include one NAOGT (UGT74F2; previously identified as a salicylic acid glycosyltransferases) and two NANGTs (UGT76C4 and UGT76C5). Arabidopsis mutants of UGT74F2 accumulate higher levels of free NA, but not salicylic acid, than that of the wild type, and this inversely correlated with seed germination rates under various abiotic stresses. The germination defect of the ugt74f2-1 mutant could be fully complemented by overexpression of UGT74F2. These observations, together with comprehensive chemical analysis, suggest that NA glycosylation may function to protect plant cells from the toxicity of NA overaccumulation during seed germination. Combined with phylogenetic analysis, our results suggest that NAOGTs arose recently in the Brassicaceae family and may provide a fitness benefit. The multifunctionality of UGT74F2 in Arabidopsis is also investigated and discussed.