National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, 430070, China.
Institute of Tropical Agriculture and Forestry of Hainan University, Haikou, 570288, China.
Sci China Life Sci. 2020 Jul;63(7):1037-1052. doi: 10.1007/s11427-019-1604-3. Epub 2020 Feb 25.
Although natural variations in rice flavonoids exist, and biochemical characterization of a few flavonoid glycosyltransferases has been reported, few studies focused on natural variations in tricin-lignan-glycosides and their underlying genetic basis. In this study, we carried out metabolic profiling of tricin-lignan-glycosides and identified a major quantitative gene annotated as a UDP-dependent glycosyltransferase OsUGT706C2 by metabolite-based genome-wide association analysis. The putative flavonoid glycosyltransferase OsUGT706C2 was characterized as a flavonoid 7-O-glycosyltransferas in vitro and in vivo. Although the in vitro enzyme activity of OsUGT706C2 was similar to that of OsUGT706D1, the expression pattern and induced expression profile of OsUGT706C2 were very different from those of OsUGT706D1. Besides, OsUGT706C2 was specifically induced by UV-B. Constitutive expression of OsUGT706C2 in rice may modulate phenylpropanoid metabolism at both the transcript and metabolite levels. Furthermore, overexpressing OsUGT706C2 can enhance UV-B tolerance by promoting ROS scavenging in rice. Our findings might make it possible to use the glycosyltransferase OsUGT706C2 for crop improvement with respect to UV-B adaptation and/or flavonoid accumulation, which may contribute to stable yield.
尽管稻米类黄酮存在天然变异，并且已经报道了几种类黄酮糖基转移酶的生化特性，但很少有研究关注tricnin-lignan-糖苷的天然变异及其潜在的遗传基础。在这项研究中，我们对 tricin-lignan-糖苷进行了代谢组学分析，并通过基于代谢物的全基因组关联分析鉴定了一个主要的数量性状基因，注释为 UDP 依赖性糖基转移酶 OsUGT706C2。推测的类黄酮糖基转移酶 OsUGT706C2 在体外和体内被鉴定为类黄酮 7-O-糖基转移酶。尽管 OsUGT706C2 的体外酶活性与 OsUGT706D1 相似，但 OsUGT706C2 的表达模式和诱导表达谱与 OsUGT706D1 非常不同。此外，OsUGT706C2 还受到 UV-B 的特异性诱导。OsUGT706C2 在水稻中的组成型表达可能会在转录和代谢物水平上调节苯丙烷代谢。此外，过量表达 OsUGT706C2 可以通过促进水稻中 ROS 的清除来增强 UV-B 耐受性。我们的研究结果可能使利用糖基转移酶 OsUGT706C2 进行作物改良成为可能，以适应 UV-B 和/或类黄酮积累，这可能有助于稳定产量。
