Abstract
RPK1, a leucine-rich repeat (LRR) receptor kinase in the plasma membrane, is upregulated by ABA in Arabidopsis. Repression of RPK1 expression in Arabidopsis decreased sensitivity to ABA during germination, growth, and stomatal closure. We produced the transgenic plants overexpressing the RPK1 protein and analyzed their phenotypes. The transgenic plants showed growth retardation and increased ABA sensitivity in root growth and stomatal closure. Reactive oxygen species (ROS) act as second messengers in ABA signaling. Oxidative stress responses were altered in the RPK1 knockout and the RPK1 overexpressor. Expression levels of stress- and ROS- responsive genes in rpk1-1 were decreased compared with those in wild-type, whereas these expression levels in the RPK1 overexpressor were higher than those in wild-type. Overexpression of RPK1 improved tolerance to drought stress in Arabidopsis. These results suggest that RPK1 mediates ROS signaling pathway, which regulates ROS production and scavenging during drought stress.
