State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
Plant Cell Rep. 2011 Nov;30(11):2097-104. doi: 10.1007/s00299-011-1116-9. Epub 2011 Jul 7.
Mitogen-activated protein kinase kinase (MAPKKs) are important components of MAPK cascades, which are universal signal transduction modules and play important role in regulating both plant development and biotic or abiotic stress responses. In this study, we identified the group C MAPKK gene, ZmMKK4, in maize (Zea mays L.). Overexpression of ZmMKK4 in tobacco enhanced tolerance to osmotic stress by increased proline content and antioxidant enzyme (POD) activities compared with wild-type plants. RT-PCR revealed that one peroxidase (POX) gene, NtPOX1, was higher in ZmMKK4-overexpressing plants than in the wild-type plants. In addition, the accumulation of reactive oxygen species (ROS) in ZmMKK4-overexpressing plants is much less than that of wild-type plants. These results suggest that ZmMKK4 may be involved in ROS signaling. Taken together, these results indicate that ZmMKK4 is a positive regulator of osmotic stress by regulating scavenging of ROS in plants.
丝裂原活化蛋白激酶激酶（MAPKKs）是 MAPK 级联反应的重要组成部分，MAPK 级联反应是普遍的信号转导模块，在调节植物发育和生物或非生物胁迫反应方面发挥着重要作用。在本研究中，我们在玉米（Zea mays L.）中鉴定出了 C 组 MAPKK 基因 ZmMKK4。与野生型植物相比，过量表达 ZmMKK4 的烟草中脯氨酸含量和抗氧化酶（POD）活性增加，增强了对渗透胁迫的耐受性。RT-PCR 显示，一个过氧化物酶（POX）基因 NtPOX1 在 ZmMKK4 过表达植物中的表达高于野生型植物。此外，ZmMKK4 过表达植物中活性氧（ROS）的积累比野生型植物少得多。这些结果表明 ZmMKK4 可能参与 ROS 信号转导。综上所述，这些结果表明 ZmMKK4 通过调节植物中 ROS 的清除来正向调节渗透胁迫。
