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A UDP ‐glucosyltransferase functions in both acylphloroglucinol glucoside and anthocyanin biosynthesis in strawberry ( Fragaria × ananassa )
Author(s) -
Song Chuankui,
Zhao Shuai,
Hong Xiaotong,
Liu Jingyi,
Schulenburg Katja,
Schwab Wilfried
Publication year - 2016
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13140
Subject(s) - glucosyltransferase , fragaria , chalcone synthase , biochemistry , chemistry , glucoside , glycosylation , anthocyanin , biosynthesis , glycosyltransferase , biology , enzyme , botany , food science , medicine , alternative medicine , pathology
Summary Physiologically active acylphloroglucinol ( APG ) glucosides were recently found in strawberry ( Fragaria sp.) fruit. Although the formation of the APG aglycones has been clarified, little is known about APG glycosylation in plants. In this study we functionally characterized ripening‐related glucosyltransferase genes in Fragaria by comprehensive biochemical analyses of the encoded proteins and by a RNA interference ( RNA i) approach in vivo . The allelic proteins UGT 71K3a/b catalyzed the glucosylation of diverse hydroxycoumarins, naphthols and flavonoids as well as phloroglucinols, enzymatically synthesized APG aglycones and pelargonidin. Total enzymatic synthesis of APG glucosides was achieved by co‐incubation of recombinant dual functional chalcone/valerophenone synthase and UGT 71K3 proteins with essential coenzyme A esters and UDP ‐glucose. An APG glucoside was identified in strawberry fruit which has not yet been reported in other plants. Suppression of UGT 71K3 activity in transient RNA i‐silenced fruits led to a loss of pigmentation and a substantial decrease of the levels of various APG glucosides and an anthocyanin. Metabolite analyses of transgenic fruits confirmed UGT 71K3 as a UDP ‐glucose: APG glucosyltransferase in planta . These results provide the foundation for the breeding of fruits with improved health benefits and for the biotechnological production of bioactive natural products.