VlbZIP30 of grapevine functions in drought tolerance via the abscisic acid core signaling pathway

Drought stress limits the growth and development of grapevines, thereby reducing productivity, but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized. Here, we characterized a group A bZIP gene from 9Kyoho9 grapevine, VlbZIP30, which was shown to be induced by abscisic acid (ABA) and dehydration stress. Overexpression of VlbZIP30 in transgenic Arabidopsis enhanced dehydration tolerance during seed germination, and in the seedling and adult stages. Transcriptome analysis revealed that a major proportion of ABA- and/or drought-responsive genes are transcriptionally regulated by VlbZIP30 during ABA or mannitol treatment at the cotyledon greening stage. We identified an A. thaliana G-box motif (CACGTG) and a potential grapevine G-box motif (MCACGTGK) in the promoters of the 39 selected A. thaliana genes up-regulated in the transgenic plants and in the 35 grapevine homologs, respectively. Subsequently, using two grapevine-related databases, we found that 74% and 84% (a total of 27 genes) of the detected grapevine genes were significantly up-regulated by ABA and drought stress, respectively, suggesting that these 27 genes involve in ABA or dehydration stress and may be regulated by VlbZIP30 in grapevine. We propose that VlbZIP30 functions as a positive regulator of drought-responsive signaling in the ABA core signaling pathway.