Overexpression of a maize MYB48 gene confers drought tolerance in transgenic arabidopsis plants

MYBs are a vital family of transcription factors that play critical roles in plant development and stress response. However, knowledge concerning the functions of MYBs in the non-model plants is still limited. In this study, we isolated a R1-type MYB gene from maize (Zea mays L.), designated as ZmMYB48. Quantitative RT-PCR analysis demonstrated that ZmMYB48 expression was induced by drought and ABA treatments. Subcellular localization analysis revealed that ZmMYB48 protein was targeted to the nucleus in tobacco leaf epidermal cells. Transactivation assay in yeast demonstrated that ZmMYB48 had transcriptional activation ability. Heterologous overexpression of ZmMYB48 in Arabidopsis remarkably improved plant tolerance to drought stress, as determined through physiological analyses of survival rate, relative water content, malonaldehyde content, relative electrolyte leakage and proline content. Moreover, overexpression of ZmMYB48 enhanced the expression of stress/ABA-responsive genes such as P5CS1, RD22, RD29B and ABI1. In addition, ZmMYB48-overexpressing plants accumulated higher content of ABA than WT plants under drought stress. These results demonstrate that ZmMYB48 might act as a positive regulator that participates in the drought stress response through ABA signalling.