Differentially evolved glucosyltransferases determine natural variation of rice flavone accumulation and UV-tolerance

Meng Peng,Takayuki Tohge,Zhigang Zheng,Junjie Zhou,Alisdair R Fernie,Jie Luo,Xianqing Liu,Elsayed Nishawy,Long Lei,Dandan Lu,Raheel Shahzad,Shouchuang Wang,Ambreen Gul,Hizar Subthain,Shuangqian Shen

doi:10.1038/s41467-017-02168-x

Meng Peng, Takayuki Tohge + Show 13 more

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https://doi.org/10.1038/s41467-017-02168-x

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Decoration 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.

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Decoration 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
We show that F7GlcT and F5GlcT enzymes evolved independently in plants, and provide evidence that functional allelic variation in these genes corresponds to the level of UV exposure and that lines overexpressing OsUGT706D1 and OsUGT707A2 have enhanced UV tolerance, indicating that tapping the natural variation inherent in these genes may represent a useful route to provide food security
One of the main model monocots, which has the highest accumulation of most flavones, and is of massive importance to the human diet, for assessing the natural variation in flavone content and dissecting its genetic and biochemical bases

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Introduction

Decoration 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. Flavonoids are a group of plant secondary metabolites playing important roles in a wide range of physiological processes[4,5,6] including ultraviolet-B (UV-B, 280–315 nm) protection[7,8] which is becoming increasingly important for yield stability in the face of present levels of environmental deterioration[9,10]. Their beneficial effects on human health as a dietary source of antioxidants attract increasing attention[11,12]. Glycosylation of flavonoids is usually catalyzed by UDPdependent glycosyltransferases (UGTs)[20] exceptions have been reported in carnation (Dianthus caryophyllus)[21], rice (Oryza sativa)[22], and Arabidopsis (Arabidopsis thaliana)[23]

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