Abstract
RPK1, a leucine-rich repeat (LRR) receptor kinase in the plasma membrane, is upregulated by ABA in Arabidopsis. We analyzed the phenotypes of T-DNA insertion mutants and RPK1-antisense plants. Repression of RPK1 expression in Arabidopsis decreased sensitivity to ABA during germination, growth, and stomatal closure. We then produced the C-terminal hemagglutinin (HA)-tagged RPK1 construct driven by the CaMV35S promoter and introduced into Arabidopsis plants. The transgenic plants overexpressing RPK1 showed weak growth retardation and increased ABA sensitivity in root growth and stomatal closure. The overexpression of RPK1-HA improved tolerance to drought stress. Expression levels of stress-responsive genes in the transgenic plants overexpressing RPK1-HA were higher than those in wild type plants. Furthermore, the oxidative stress responses were altered in the RPK1-knockout and the transgenic plants overexpressing RPK1-HA. We will discuss the molecular mechanism of RPK1 signaling pathway.
