title: The Arabidopsis short-chain dehydrogenase/reductase 3, an abscisic acid deficient 2 homolog, is involved in plant defense responses but not in ABA biosynthesis.
abstract: ABSCISIC ACID DEFICIENT2 (ABA2) encodes a short-chain dehydrogenase/reductase1 (SDR1) that catalyzes the multi-step conversion of xanthoxin to abscisic aldehyde during abscisic acid (ABA) biosynthesis in Arabidopsis thaliana. In this study, AtSDR2 and AtSDR3, the two closest homologs to AtABA2, were investigated for their potential role in ABA biosynthesis. AtSDR2 showed undetectable transcription in plants grown under normal conditions or under stress. AtSDR3 and AtABA2 have different spatial and temporal expression patterns. Complementation testing demonstrated that the pABA2::SDR3 transgene failed to complement the aba2 mutant phenotype, and that transgenic plants showed the same levels of ABA as the aba2 mutants. These data suggest that AtSDR3 confers no functional redundancy to AtABA2 in ABA biosynthesis. Interestingly, microarray data derived from Genevestigator suggested that AtSDR3 might have a function that is related to plant defense. Pseudomonas syringae pv. tomato (Pst) DC3000 infection and systemic acquired resistance (SAR) activator application further demonstrated that AtSDR3 plays an important role in plant defense responses at least partially through the regulation of AtPR-1 gene expression.
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan.
authors.forename: San-Gwang
authors.initials: SG
authors.lastname: Hwang
authors.forename: Nai-Chun
authors.initials: NC
authors.lastname: Lin
authors.forename: Yi-Yun
authors.initials: YY
authors.lastname: Hsiao
authors.forename: Ching-Hsuan
authors.initials: CH
authors.lastname: Kuo
authors.forename: Pi-Fang
authors.initials: PF
authors.lastname: Chang
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Deng
authors.forename: Ming-Hau
authors.initials: MH
authors.lastname: Chiang
authors.forename: Hwei-Ling
authors.initials: HL
authors.lastname: Shen
authors.forename: Chao-Ying
authors.initials: CY
authors.lastname: Chen
authors.forename: Wan-Hsing
authors.initials: WH
authors.lastname: Cheng
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis* / Q000235:genetics; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D057865:Plant Immunity; D044224:Pseudomonas syringae / Q000276:immunology / Q000472:pathogenicity; D016415:Sequence Alignment; D019076:Transgenes
chemical_list: D029681:Arabidopsis Proteins; C077262:PR-1 protein, Arabidopsis; D000040:Abscisic Acid; C469255:ABA2 protein, Arabidopsis; D000429:Alcohol Oxidoreductases; C532784:menthone (3S)-neomenthol reductase, Arabidopsis