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

Plant Cell Environ. 2019 Feb;42(2):495-508. doi: 10.1111/pce.13428. Epub 2018 Sep 17.

Abstract

Flavones, 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 in floral tissues. However, in related species such as 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. 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 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.

Keywords: DNA damage; UV-B radiation; Zea mays; apigenin; flavones.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Apigenin / metabolism
  • Apigenin / physiology*
  • Arabidopsis / metabolism
  • Cytochrome P-450 Enzyme System / metabolism*
  • DNA Damage / radiation effects
  • Mixed Function Oxygenases / metabolism*
  • Plant Proteins / metabolism
  • Plant Proteins / physiology*
  • Plants, Genetically Modified
  • Ultraviolet Rays / adverse effects*
  • Zea mays / enzymology
  • Zea mays / metabolism*
  • Zea mays / radiation effects

Substances

  • Plant Proteins
  • Apigenin
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • cytochrome P-450 CYP93B1 (Glycyrrhiza echinata)
  • flavone synthase I