AbstractDecoration of phytochemicals contributes to the majority of metabolic diversity in nature, whereas how this process alters the biological functions of their precursor molecules remains to be investigated. Flavones, an important yet overlooked subclass of flavonoids, are most commonly conjugated with sugar moieties by UDP-dependent glycosyltransferases (UGTs). Here, we report that the natural variation of rice flavones is mainly determined by OsUGT706D1 (flavone 7-O-glucosyltransferase) and OsUGT707A2 (flavone 5-O-glucosyltransferase). UV-B exposure and transgenic evaluation demonstrate that their allelic variation contributes to UV-B tolerance in nature. Biochemical characterization of over 40 flavonoid UGTs reveals their differential evolution in angiosperms. These combined data provide biochemical insight and genetic regulation into flavone biosynthesis and additionally suggest that adoption of the positive alleles of these genes into breeding programs will likely represent a potential strategy aimed at producing stress-tolerant plants.
摘要
植物化学物质的修饰对自然界的代谢多样性起着重要作用,然而这一过程如何改变它们前体分子的生物功能尚待研究。黄酮类化合物是一类重要但常被忽视的类黄酮类化合物,它们通常通过UDP依赖型糖苷转移酶(UGTs)与糖基结合。在这里,我们报告了水稻黄酮类化合物的自然变异主要由OsUGT706D1(黄酮7-O-葡萄糖基转移酶)和OsUGT707A2(黄酮5-O-葡萄糖基转移酶)确定。紫外线B暴露和转基因评估表明它们的等位变异在自然界中有助于UV-B耐受性。对超过40种黄酮类化合物UGTs的生化特性表征揭示了它们在被子植物中的差异进化。这些综合数据提供了关于黄酮合成的生化见解和遗传调控,并额外建议将这些基因的正等位基因引入育种计划,可能代表一种旨在生产耐逆植物的潜在策略。