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The MYB 5‐driven MBW complex recruits a WRKY factor to enhance the expression of targets involved in vacuolar hyper‐acidification and trafficking in grapevine
Author(s) -
Amato Alessandra,
Cavallini Erika,
Walker Amanda R.,
Pezzotti Mario,
Bliek Mattijs,
Quattrocchio Francesca,
Koes Ronald,
Ruperti Benedetto,
Bertini Edoardo,
Zei Sara,
Tornielli Giovanni B.
Publication year - 2019
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.14419
Subject(s) - wrky protein domain , myb , transcription factor , biology , transcriptome , gene , microbiology and biotechnology , gene expression , genetics
Summary The accumulation of secondary metabolites and the regulation of tissue acidity contribute to the important traits of grape berry and influence plant performance in response to abiotic and biotic factors. In several plant species a highly conserved MYB–bHLH– WD ( MBW ) transcriptional regulatory complex controls flavonoid pigment synthesis and transport, and vacuolar acidification in epidermal cells. An additional component, represented by a WRKY ‐type transcription factor, physically interacts with the complex increasing the expression of some target genes and adding specificity for other targets. Here we investigated the function of MBW( W) complexes involving two MYB s (Vv MYB 5a and Vv MYB 5b) and the WRKY factor Vv WRKY 26 in grapevine ( Vitis vinifera L.). Using transgenic grapevine plants we showed that these complexes affected different aspects of morphology, plant development, pH regulation, and pigment accumulation. Transcriptomic analysis identified a core set of putative target genes controlled by Vv MYB 5a, Vv MYB 5b, and Vv WRKY 26 in different tissues. Our data indicated that Vv WRKY 26 enhances the expression of selected target genes induced by Vv MYB 5a/b. Among these targets are genes involved in vacuolar hyper‐acidification, such as the P‐type ATP ases Vv PH 5 and Vv PH 1 , and trafficking, and genes involved in the biosynthesis of flavonoids. In addition, Vv WRKY 26 is recruited specifically by Vv MYB 5a, reflecting the functional diversification of Vv MYB 5a and Vv MYB 5b. The expression of MBWW complexes in vegetative organs, such as leaves, indicates a possible function of vacuolar hyper‐acidification in the repulsion of herbivores and/or in developmental processes, as shown by defects in transgenic grape plants where the complex is inactivated.