title: A link between magnesium-chelatase H subunit and sucrose nonfermenting 1 (SNF1)-related protein kinase SnRK2.6/OST1 in Arabidopsis guard cell signalling in response to abscisic acid.
abstract: Magnesium-chelatase H subunit [CHLH/putative abscisic acid (ABA) receptor ABAR] positively regulates guard cell signalling in response to ABA, but the molecular mechanism remains largely unknown. A member of the sucrose nonfermenting 1 (SNF1)-related protein kinase 2 family, SnRK2.6/open stomata 1 (OST1)/SRK2E, which plays a critical role in ABA signalling in Arabidopsis guard cells, interacts with ABAR/CHLH. Neither mutation nor over-expression of the ABAR gene affects significantly ABA-insensitive phenotypes of stomatal movement in the OST1 knockout mutant allele srk2e. However, OST1 over-expression suppresses ABA-insensitive phenotypes of the ABAR mutant allele cch in stomatal movement. These genetic data support that OST1 functions downstream of ABAR in ABA signalling in guard cells. Consistent with this, ABAR protein is phosphorylated, but independently of the OST1 protein kinase. Two ABAR mutant alleles, cch and rtl1, show ABA insensitivity in ABA-induced reactive oxygen species and nitric oxide production, as well as in ABA-activated phosphorylation of a K(+) inward channel KAT1 in guard cells, which is consistent with that observed in the pyr1 pyl1 pyl2 pyl4 quadruple mutant of the well-characterized ABA receptor PYR/PYL/RCAR family acting upstream of OST1. These findings suggest that ABAR shares, at least in part, downstream signalling components with PYR/PYL/RCAR receptors for ABA in guard cells; though cch and rtl1 show strong ABA-insensitive phenotypes in both ABA-induced stomatal closure and inhibition of stomatal opening, while the pyr1 pyl1 pyl2 pyl4 quadruple mutant shows strong ABA insensitivity only in ABA-induced stomatal closure. These data establish a link between ABAR/CHLH and SnRK2.6/OST1 in guard cell signalling in response to ABA.
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Liang
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Lu
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Shang-Chuan
authors.initials: SC
authors.lastname: Jiang
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Yong-Tao
authors.initials: YT
authors.lastname: Yu
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Bi
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Xin
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China zhangdp@tsinghua.edu.cn wangxf@biomed.tsinghua.edu.cn.
authors.forename: Xiao-Fang
authors.initials: XF
authors.lastname: Wang
authors.affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China zhangdp@tsinghua.edu.cn wangxf@biomed.tsinghua.edu.cn.
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Zhang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D008190:Lyases / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism; D010766:Phosphorylation; D054046:Plant Stomata / Q000235:genetics / Q000502:physiology*; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D000040:Abscisic Acid; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis; D008190:Lyases; C561080:GUN5 protein, Arabidopsis
keywords: Abscisic acid signalling; Arabidopsis thaliana; Mg-chelatase H subunit; SNF1-related protein kinase SnRK2.6/OST1; guard cell; stomatal movement.