Transcriptome analysis and functional validation reveal that VvMYB1 is a positive regulator of drought tolerance in...

Drought stress severely constrains grape growth and productivity, yet the molecular mechanisms underlying drought adaptation remain incompletely understood. This study aimed to identify key transcriptional regulators involved in grape drought responses and to evaluate their functional roles.

To address this, callus tissues derived from Vitis vinifera were subjected to PEG-simulated drought stress, and samples were collected at 0, 5, and 10 days for transcriptome sequencing. Differential expression analysis was performed to identify drought-responsive genes and transcription factor families. Based on expression patterns, VvMYB1 was selected for further functional characterization. Transgenic callus overexpressing VvMYB1 was generated to assess its role under drought stress.

Transcriptome analysis identified 48 transcription factor families involved in drought response, among which the MYB family was the most abundant. Functional analyses showed that OE-VvMYB1 callus exhibited enhanced drought tolerance compared with WT, as evidenced by significantly increased activities of SOD, POD, and CAT, as well as higher Pro accumulation. In contrast, MDA and H₂O₂ levels were reduced. Moreover, the expression levels of several stress-responsive genes were significantly upregulated in OE-VvMYB1 lines.

These results indicate that VvMYB1 functions as a positive regulator in grape drought response. This study provides new insights into the transcriptional regulation of drought tolerance in grape and identifies VvMYB1 as a promising candidate gene for improving stress resilience.