The grape VvMBF1 gene improves drought stress tolerance in transgenic Arabidopsis thaliana

Multiprotein bridging factor 1 (MBF1) is an evolutionarily conserved transcriptional co-activator in archaea and eukaryotes that has been demonstrated previously to play an important role in various types of stress response. In this study, a full-length MBF1 cDNA sequence (VvMBF1) was isolated from grape (Vitis labrusca × V. vinifera) and was found to be up-regulated in the leaves of grape plants following both drought and abscisic acid (ABA) treatments. Furthermore, constitutive expression of VvMBF1 in Arabidopsis thaliana enhanced drought stress tolerance in transgenic plants. To gain further insight into the role of VvMBF1 in drought resistance, we analyzed various physiological parameters related to stress response in transgenic Arabidopsis lines and found that transgenic plants were better able to prevent water loss under stress conditions than wild-type (WT) plants. This was likely due to an increase in the sensitivity of stomata to ABA, which is a well-known signaling molecule in plant drought response. In addition, dehydration stress yielded less cell damage to transgenic plants than WT plants. We also found that VvMBF1-expressing transgenic lines exhibited up-regulation of two drought-responsive genes that are known to function in the ABA-dependent drought-response pathway. Taken together, these results reveal that VvMBF1 is likely involved in drought-responsiveness in grape, and confers increased drought tolerance in transgenic plants, possibly through an ABA-dependent signal transduction pathway.