Overexpression of a multiple stress-responsive gene, ZmMPK4, enhances tolerance to low temperature in transgenic tobacco

Mitogen-activated protein kinase (MAPK) cascades play important roles in mediating biotic and abiotic stress responses. In this study, we found that ZmMPK4 protein was predominantly localized in the nucleus. Semi-quantitative RT-PCR analysis revealed that the ZmMPK4 transcription in maize leaves was up-regulated by low temperature, high temperature and exogenous signaling molecules such as hydrogen peroxide, methyl jasmonate and ethephon. Hydrogen peroxide acted as second messenger to mediate 4 °C-induced up-regulation of ZmMPK4 mRNA. Transgenic tobacco of overexpressing ZmMPK4 accumulated less reactive oxygen species (ROS), more peroxidase and catalase activities, more proline and soluble sugar contents, and more stress-responsive genes expression, leading to enhancing low temperature stress tolerance compared to the control plants. Taken together, these results strongly suggest that ZmMPK4 positively regulates low temperature stress tolerance in plants.

► ZmMPK4 was predominantly localized in the nucleus.
► ZmMPK4 was induced by multiple abiotic stresses and signaling molecules in maize leaves.
► H2O2 is required for 4 °C-induced increase of ZmMPK4 mRNA.
► Overexpression of ZmMPK4 enhanced tolerance to low temperature stress in transgenic tobacco.