title: Overproduction of the membrane-bound receptor-like protein kinase 1, RPK1, enhances abiotic stress tolerance in Arabidopsis.
abstract: RPK1 (receptor-like protein kinase 1) localizes to the plasma membrane and functions as a regulator of abscisic acid (ABA) signaling in Arabidopsis. In our current study, we investigated the effect of RPK1 disruption and overproduction upon plant responses to drought stress. Transgenic Arabidopsis overexpressing the RPK1 protein showed increased ABA sensitivity in their root growth and stomatal closure and also displayed less transpirational water loss. In contrast, a mutant lacking RPK1 function, rpk1-1, was found to be resistant to ABA during these processes and showed increased water loss. RPK1 overproduction in these transgenic plants thus increased their tolerance to drought stress. We performed microarray analysis of RPK1 transgenic plants and observed enhanced expression of several stress-responsive genes, such as Cor15a, Cor15b, and rd29A, in addition to H(2)O(2)-responsive genes. Consistently, the expression levels of ABA/stress-responsive genes in rpk1-1 had decreased compared with wild type. The results suggest that the overproduction of RPK1 enhances both the ABA and drought stress signaling pathways. Furthermore, the leaves of the rpk1-1 plants exhibit higher sensitivity to oxidative stress upon ABA-pretreatment, whereas transgenic plants overproducing RPK1 manifest increased tolerance to this stress. Our current data suggest therefore that RPK1 overproduction controls reactive oxygen species homeostasis and enhances both water and oxidative stress tolerance in Arabidopsis.
authors.affiliation: Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Osakabe
authors.forename: Shinji
authors.initials: S
authors.lastname: Mizuno
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tanaka
authors.forename: Kyonoshin
authors.initials: K
authors.lastname: Maruyama
authors.forename: Keishi
authors.initials: K
authors.lastname: Osakabe
authors.forename: Daisuke
authors.initials: D
authors.lastname: Todaka
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Fujita
authors.forename: Masatomo
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shinozaki
authors.forename: Kazuko
authors.initials: K
authors.lastname: Yamaguchi-Shinozaki
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D010766:Phosphorylation; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000096:biosynthesis* / Q000502:physiology*; D017382:Reactive Oxygen Species; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D011494:Protein Kinases; C105762:RPK1 protein, Arabidopsis