Genome-wide identification of the MYB transcription factor family of blackcurrant and the key role of RnMYB44 gene in drought tolerance

Based on the MYB family analysis in blackcurrant, the RnMYB44 gene was identified and shown to enhance drought tolerance. It improves plant drought resistance comprehensively by increasing reactive oxygen species (ROS) scavenging capacity, enhancing root sensitivity to abscisic acid (ABA), and enabling faster stomatal regulation to reduce water loss.

Drought is one of the main environmental stress factors affecting the decline in blackcurrant yield. The MYB transcription factor family plays an important role in the regulation of drought stress responses. Although the genome assembly and transcriptome analysis of blackcurrant under drought stress have been reported recently, the systematic identification of MYB transcription factor family and the functional characterization of its members in drought response have not been explored. This study conducted a genome-wide analysis and identification of 129 MYB transcription factors family members in blackcurrant, and combined with transcriptomics to screen out the key gene RnMYB44. By constructing Arabidopsis heterologous expression, subsequent functional validation was performed to discuss its potential role in drought stress response. Under drought stress conditions, compared with the Wild type (WT), transgenic Arabidopsis lines overexpressing RnMYB44 (OE-RnMYB44) exhibited significantly enhanced antioxidant enzyme activities, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and demonstrated higher reactive oxygen species (ROS) scavenging capacity; increased sensitivity of Arabidopsis roots to abscisic acid (ABA); and more rapid regulation of stomatal conductance to reduce water loss. These results clearly demonstrate that RnMYB44 can enhance the drought tolerance of Arabidopsis, providing an important theoretical basis for further studies on the drought tolerance of blackcurrant.