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A negative MYB regulator of proanthocyanidin accumulation, identified through expression quantitative locus mapping in the grape berry
Author(s) -
Huang YungFen,
Vialet Sandrine,
Guiraud JeanLuc,
Torregrosa Laurent,
Bertrand Yves,
Cheynier Véronique,
This Patrice,
Terrier Nancy
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12557
Subject(s) - quantitative trait locus , biology , myb , genetics , locus (genetics) , transcriptome , gene , candidate gene , gene expression profiling , gene expression , population , demography , sociology
Summary Flavonoids are secondary metabolites with multiple functions. In grape ( Vitis vinifera ), the most abundant flavonoids are proanthocyanidins ( PA s), major quality determinants for fruit and wine. However, knowledge about the regulation of PA composition is sparse. Thus, we aimed to identify novel genomic regions involved in this mechanism. Expression quantitative trait locus (e QTL ) mapping was performed on the transcript abundance of five downstream PA synthesis genes (dihydroflavonol reductase ( V v DFR ), leucoanthocyanidin dioxygenase ( V v LDOX ), leucoanthocyanidin reductase ( V v LAR 1 ), V v LAR 2 and anthocyanidin reductase ( V v ANR )) measured by real‐time quantitative PCR on a pseudo F 1 population in two growing seasons. Twenty‐one e QTL s were identified; 17 of them did not overlap with known candidate transcription factors or cis ‐regulatory sequences. These novel loci and the presence of digenic epistasis support the previous hypothesis of a polygenic regulatory mechanism for PA biosynthesis. In a genomic region co‐locating e QTL s for V v DFR , V v LDOX and V v LAR 1 , gene annotation and a transcriptomic survey suggested that V v MYBC 2‐ L 1 , a gene coding for an R 2 R 3‐ MYB protein, is involved in regulating PA synthesis. Phylogenetic analysis showed its high similarity to characterized negative MYB factors. Its spatiotemporal expression profile in grape coincided with PA synthesis. Its functional characterization via overexpression in grapevine hairy roots demonstrated its ability to reduce the amount of PA and to down‐regulate expression of PA genes.