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

SILVANA RIGHINI ARAMBURU; EDUARDO JOSE RODRIGUEZ; CARLA BEROSICH; ERICH GROTEWOLD; PAULA CASATI; MARÍA LORENA FALCONE-FERREYRA

PLANT, CELL AND ENVIRONMENT (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 42 p. 495 - 508

0140-7791

Flavones, one of the largest groups of flavonoids, have beneficial effects on human health andare considered of high nutritional value. Previously, we demonstrated that maize type I flavonesynthase (ZmFNSI) is one of the enzymes responsible for the synthesis of O‐glycosyl flavones infloral tissues. However, in related species such as rice and sorghum, type II FNS enzymes alsocontribute to flavone biosynthesis. In this work, we provide evidence that maize has both one FNSIand one FNSII flavone synthases. Arabidopsis transgenic plants expressing each FNS enzyme weregenerated to validate the role of flavones in protecting plants against UV‐B radiation. Here, wedemostrate that ZmCYP93G7 (FNSII) has flavone synthase activity and is able to complement theArabidopsis dmr6 mutant, restoring the susceptibility to Pseudomonas syringae. ZmFNSII expressionis controlled by the C1/PL1 + R/B anthocyanin transcriptional complexes, and both ZmFNSI andZmFNSII are regulated by UV‐B. Arabidopsis transgenic plants expressing ZmFNSI or ZmFNSII thataccumulate apigenin exhibit less UV‐B‐induced damage than wild‐type plants. Together, we showthat maize has two FNS‐type enzymes that participate in the synthesis of apigenin, conferringprotection against UV‐B radiation.Brief Summary Here, we show that maize has an active type II flavone synthase enzyme(ZmCYP93G7), in addition to the previously reported type I FNS (ZmFNSI), both involved inapigenin flavone synthesis. Furthermore, we provide evidence that apigenin confers protectionagainst UV‐B radiation induced damage.