Apigenin produced by maize flavone synthase I and II protects plants against UV-B-induced damage

First author: Silvana Righini; Affiliations: Universidad Nacional de Rosario (国立罗萨里奥大学): Rosario, Argentina

Corresponding author: María Lorena Falcone Ferreyra

Flavones (黄酮), one of the largest groups of flavonoids, have beneficial effects on human health and are considered of high nutritional value. Previously, we demonstrated that maize type I flavone synthase (ZmFNSI) is one of the enzymes responsible for the synthesis of O‐glycosyl flavones (O-糖基黄酮) in floral tissues. However, in related species like rice and sorghum, type II FNS enzymes also contribute to flavone biosynthesis. In this work, we provide evidence that maize has both one FNSI and one FNSII flavone synthases. Arabidopsis transgenic plants expressing each FNS enzyme were generated to validate the role of flavones in protecting plants against UV‐B radiation. Here, we demostrate that ZmCYP93G7 (FNSII) has flavone synthase activity and is able to complement the Arabidopsis dmr6 mutant, restoring the susceptibility to Pseudomonas syringae (丁香假单胞菌). ZmFNSII expression is controlled by the C1/PL1 + R/B anthocyanin transcriptional complexes; and both ZmFNSI and ZmFNSII are regulated by UV‐B. Arabidopsis transgenic plants expressing ZmFNSI or ZmFNSII that accumulate apigenin (芹菜素) exhibit less UV‐B‐induced damage than wild type plants. Together, we show that maize has two FNS type enzymes that participate in the synthesis of apigenin, conferring protection against UV‐B radiation.

黄酮是植物生物类黄酮代谢物的最大一个分支，被证明有益于人类的健康，并具有极高的营养价值。作者在之前的研究中揭示了玉米I类黄酮合酶ZmFNSI作用于花组织中的O-糖基黄酮合成。然而，在玉米和高粱中，II类黄酮合酶同样作用于黄酮的生物合成。本文的研究显示玉米中同时存在I类和II类的黄酮合酶。任何一个的黄酮合酶拟南芥转基因植株都显示了黄酮在保护植物不受紫外辐射伤害的作用。玉米II类黄酮合酶ZmCYP93G7具有黄酮合酶活性，并且互补于拟南芥dmr6突变体，能够拯救该突变体对于丁香假单胞菌的易感性。ZmFNSII的表达受到C1/PL1 + R/B花青素转录调控复合物的调控，并且ZmFNSI和ZmFNSII都受到紫外辐射的调控。拟南芥转ZmFNSI和ZmFNSII植株相较于野生型会积累芹菜素减少植株受紫外辐射诱导的损伤。综上，本文的研究显示FNS类合酶部分参与芹菜素的生物合成，进而赋予植株对紫外辐射的抗性。

doi: https://doi.org/10.1111/pce.13428

Journal: Plant, Cell & Environment

First Published: 30 August, 2018

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