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Solar UV light regulates flavonoid metabolism in apple ( Malus x domestica)
Author(s) -
HenryKirk Rebecca A.,
Plunkett Blue,
Hall Miriam,
McGhie Tony,
Allan Andrew C.,
Wargent Jason J.,
Espley Richard V.
Publication year - 2018
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.13125
Subject(s) - flavonols , anthocyanin , flavonoid biosynthesis , flavonoid , malus , chalcone synthase , plant physiology , ripening , botany , chemistry , biology , proanthocyanidin , biochemistry , hypocotyl , gene expression , horticulture , food science , gene , antioxidant , polyphenol , transcriptome
Ultraviolet‐B light (UV‐B) is one environmental signal perceived by plants that affects the flavonoid pathway and influences the levels of anthocyanins, flavonols, and proanthocyanidins. To understand the mechanisms underlying UV exposure, apple trees were grown under spectral filters that altered transmission of solar UV light. Fruit analysis showed that UV induced changes in physiology, metabolism, and gene expression levels during development over a season. These changes were sustained after storage. Under low UV, ripening was delayed, fruit size decreased, and anthocyanin and flavonols were reduced. Expression analysis showed changes in response to UV light levels for genes in the regulation and biosynthesis of anthocyanin and flavonols. Transcription of flavonol synthase (FLS), ELONGATED HYPOCOTYL 5 (HY5), MYB10, and MYB22 were down‐regulated throughout fruit development under reduced UV. Functional testing showed that the FLS promoter was activated by HY5, and this response was enhanced by the presence of MYB22. The MYB22 promoter can also be activated by the anthocyanin regulator, MYB10. As ambient levels of UV light vary around the globe, this study has implications for future crop production, the quality of which can be determined by the response to UV.