Abstract
Abscisic acid (ABA) plays an important role in seed maturation, seed dormancy, stomatal closure, and stress response. 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; microarray and RNA gel analysis showed that many ABA-inducible genes are downregulated in these plants. Furthermore, overexpression of the RPK1 LRR domain alone or fused with the BRI1 kinase domain in plants resulted in ABA-sensitive phenotypes. We then produced the C-terminal hemagglutinin (HA)-tagged RPK1 construct driven by the CaMV35S promoter and introduced into Arabidopsis plants. These plants overexpressing RPK1 showed weak growth retardation and increased ABA sensitivity in root growth and stomatal closure. We will present further details of the plants overexpressing RPK1-HA.
