Expression of multi-copy flavonoid pathway genes coincides with anthocyanin, flavonol and flavan-3-ol accumulation of grapevine

The biosynthetic pathways of main grape flavonoids: anthocyanins, flavonols, and flavan-3-ols, hold in common the early step enzymes of biosynthetic pathway: chalcone synthase (CHS), chalcone isomerase (CHI), and flavanone 3-hydroxylase (F3H), the genes of which are multi-copied in the grape genome. The ratios of mRNA levels of the three Chss ( Chs1, Chs2 , and Chs3 ), as well as those of the two Chis ( Chi1 and Chi2 ) and those of the two F3hs ( F3h1 and F3h2 ), were different among organs, even though no organ-specificity was observed in the strictest sense. Multiple regression analysis demonstrated that the transcription of particular genes significantly coincided with the biosynthesis of a particular flavonoid: the transcription of Chi2 coincided with flavan-3-ol; Chs1, Chs2, F3h1, and F3h2 with flavonol; and Chs2, Chs3, and F3h2 with anthocyanin biosynthesis. Thus, the transcription of these multi-copy genes is likely induced differently for the biosyntheses of anthocyanins, flavonols, and flavan-3-ols.