R2R3-MYB TRANSCRIPTION FACTOR, MYB6, , FROM GRAPES CONFERS ENHANCED SALT STRESS TOLERANCE IN TRANSGENIC TOBACCO

The R2R3-MYB family genes encode numerous highly conserved transcription factors that are critical for the plant development and stress response, but there is currently little information on the role of this genes in grape salt tolerance. Salt stress limits grape production, resulting in considerable annual reduction in both yield and quality. The identification and analysis of the stress-related genes from grapes could lead to the development of cultivars that can be stress-tolerant. We identified MYB6, , a R2R3-MYB transcription factor from grape 'Yatomi Rose' ( Vitis vinifera L.), and characterized the stress response phenotypes of tobacco lines overexpressing this gene. It was found that the root length, fresh weight, and height of VvMYB6-overexpression (VvMYB6-OE) VvMYB6-OE) tobacco was significantly different from that of the empty vector-transformed (EV) tobacco under 0.1 M NaCl conditions. Under salt stress, the blue-brown patches of transgenic tobacco leaves with VvMYB6-OE-OE were less than those of EV-transformed tobacco, and the color was lighter than that of EV tobacco, indicating a reduction in reactive oxygen species (ROS). VvMYB6-OE-OE tobacco plants showed less electrolyte leakage, whereas an increase in the chlorophyll and proline content was observed. Additionally, the VvMYB6-OE-OE tobacco plants exhibited reduced malondialdehyde (MDA) and H2O2 2 O 2 content due to the increase in the activity of the antioxidant enzymes. Taken together, these findings significantly improve the current understanding of the role of the R2R3-MYB transcription factors in plant salt stress tolerance and could lead to the development of more stress tolerant lines.