Expression of the maize MYB transcription factor ZmMYB3R enhances drought and salt stress tolerance in transgenic plants.

MYB proteins are major transcription factors that play significant roles in plant defenses against various stresses. However, available information regarding stress-related MYB genes in maize is minimal. Herein, a maize MYB gene, ZmMYB3R, was cloned and functionally characterized. Subcellular localisation analysis showed that ZmMYB3R is localised to the nucleus. Yeast one-hybrid results revealed that ZmMYB3R has trans-activation activity, and a minimal activation domain at the C-terminus spanning residues 217-563. Gene expression analysis suggested that ZmMYB3R was induced by drought, salt and abscisic acid (ABA). Transgenic Arabidopsis plants overexpressing ZmMYB3R displayed enhanced growth performance and higher survival rates, elevated catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) enzyme activities, increased sensitivity to ABA, and regulation of the stomatal aperture, suggesting that ZmMYB3R enhances tolerance to drought and salt stress. qRT-PCR assays revealed elevated expression levels of stress/ABA genes in transgenic plants following stress treatments. Moreover, transgenic plants accumulated higher ABA content than wild-type plants under drought and salt stress conditions. Collectively, these results indicate that ZmMYB3R is a positive transcription factor that enhances tolerance to drought and salt stress via an ABA-dependent pathway. The findings may prove useful for engineering economically important crops.