title: Evidence of Arabidopsis salt acclimation induced by up-regulation of HY1 and the regulatory role of RbohD-derived reactive oxygen species synthesis.
abstract: In Arabidopsis thaliana, a family of four genes (HY1, HO2, HO3 and HO4) encode haem oxygenase (HO), and play a major role in phytochrome chromophore biosynthesis. To characterize the contribution of the various haem oxygenase isoforms involved in salt acclimation, the effects of NaCl on seed germination and primary root growth in Arabidopsis wild-type and four HO mutants (hy1-100, ho2, ho3 and ho4) were compared. Among the four HO mutants, hy1-100 displayed maximal sensitivity to salinity and showed no acclimation response, whereas plants over-expressing HY1 (35S:HY1) exhibited tolerance characteristics. Mild salt stress stimulated biphasic increases in RbohD transcripts and production of reactive oxygen species (ROS) (peaks I and II) in wild-type. ROS peak I-mediated HY1 induction and subsequent salt acclimation were observed, but only ROS peak I was seen in the hy1-100 mutant. A subsequent test confirmed the causal relationship of salt acclimation with haemin-induced HY1 expression and RbohD-derived ROS peak II formation. In atrbohD mutants, haemin pre-treatment resulted in induction of HY1 expression, but no similar response was seen in hy1-100, and no ROS peak II or subsequent salt acclimatory responses were observed. Together, the above findings suggest that HY1 plays an important role in salt acclimation signalling, and requires participation of RbohD-derived ROS peak II.
authors.affiliation: College of Life Sciences, Cooperative Demonstration Laboratory of Centrifuge Technique, Nanjing Agricultural University, and Beckman Coulter Ltd, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yan-Jie
authors.initials: YJ
authors.lastname: Xie
authors.forename: Sheng
authors.initials: S
authors.lastname: Xu
authors.forename: Bin
authors.initials: B
authors.lastname: Han
authors.forename: Ming-Zhu
authors.initials: MZ
authors.lastname: Wu
authors.forename: Xing-Xing
authors.initials: XX
authors.lastname: Yuan
authors.forename: Yi
authors.initials: Y
authors.lastname: Han
authors.forename: Quan
authors.initials: Q
authors.lastname: Gu
authors.forename: Dao-Kun
authors.initials: DK
authors.lastname: Xu
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.forename: Wen-Biao
authors.initials: WB
authors.lastname: Shen
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D054712:Salinity; D055051:Salt-Tolerant Plants / Q000201:enzymology / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D006419:Heme Oxygenase (Decyclizing); D019255:NADPH Oxidases