Grape VvMAPK9 positively regulates salt tolerance in Arabidopsis and grape callus through regulating the antioxidative system

Mitogen-activated protein kinase pathways are involved in plant resistance to a variety of adverse environmental processes, and their downstream component MAPKs play an important role in this process. However, the function of MAPKs in abiotic stresses is still far from being clear in grape ( Vitis vinifera L.). Here, we isolated a novel group B MAPK gene ( VvMAPK9 ) from grape, which is induced by different abiotic stresses such as salt, drought and high temperature (42 °C). Overexpressing VvMAPK9 in Arabidopsis thaliana significantly enhanced the tolerance to salt stress. Compared with wild type plants, the transgenic lines exhibited higher germination rate and longer root length as well better growth status under salt stress. In addition, overexpression of VvMAPK9 in grape callus also increased the salt stress tolerance and enhanced the callus’s ability to scavenge reactive oxygen species (ROS), which correlated with higher activity of ROS-related antioxidant enzymes. These results indicate that VvMAPK9 may positively regulate salt stress by regulating the antioxidative system.