Abscisic acid and hydrogen peroxide induce a novel maize group C MAP kinase gene, ZmMPK7, which is responsible for the removal of reactive oxygen species.

Mitogen-activated protein kinase (MAPK) cascades are involved in biotic and abiotic stress responses. In plants, MAPKs are classified into four groups, designated A-D. Information about group C MAPKs is limited, and, in particular, no data from maize are available. In this article, we isolated a novel group C MAPK gene, ZmMPK7, from Zea mays. Exogenous abscisic acid (ABA) and hydrogen peroxide (H(2)O(2)) induced calcium-dependant transcription of ZmMPK7. Induction of this gene in response to ABA was blocked by several reactive oxygen species (ROS) manipulators such as imidazole, Tiron, and dimethylthiourea (DMTU). This result indicates that endogenous H(2)O(2) may be required for ZmMPK7-mediated ABA signaling. Expression of ZmMPK7 in Nicotonia tobaccum caused less H(2)O(2) to accumulate and alleviated ROS-mediated injuries following submission of the plants to osmotic stress. The enhanced total peroxidase (POD) activity in transgenic tobacco plants may contribute to removal of ROS. Finally, we have shown that the ZmMPK7 protein localizes in the nucleus. These results broaden our knowledge regarding plant group C MAPK activity in response to stress signals.