title: Thylakoid membrane oxidoreductase LTO1/AtVKOR is involved in ABA-mediated response to osmotic stress in Arabidopsis.
abstract: Arabidopsis lumen thiol oxidoreductase 1 (LTO1) - the At4g35760 gene product - was previously found to be related to reactive oxygen species (ROS) accumulation. Here, we show that ROS accumulated in a mutant Arabidopsis line (lto1-2, mutant of LTO1/AtVKOR) under osmotic stress at a higher level than that observed in wild-type and transgenic complemented plants of the lto1-2 mutant (lto1-2C, transgenic complemented plants of lto1-2). Because ROS accumulation in osmotic stress is triggered by abscisic acid (ABA), an ABA-responsive gene, Annexin 1 (AnnAt1), was selected to study the response. Osmotic stress or exogenous ABA can significantly upregulate the transcription of AnnAt1 in wild-type and lto1-2C plants. Only a slight change in the transcriptional abundance of AnnAt1 was observed under osmotic stress in the lto1-2 mutant, but exogenous ABA application could increase the expression of AnnAt1, which suggested that exogenous ABA had a partial complementation role. Because the transcription of AnnAt1 is regulated by ABRE (ABA-responsive elements) binding proteins (AREBs)/ABRE binding factors (ABFs), the expression of AREBs/ABFs was also analyzed. The transcription of AREBs/ABFs in the lto1-2 mutant was not induced by osmotic stress but was significantly upregulated by exogenous ABA, which significantly differs from the wild-type and lto1-2C plant responses. Similarly, the expression of another ABA-responsive gene, RD29B (responsive to desiccation stress gene 29B), in the lto1-2 mutant was also upregulated by exogenous ABA. The partial complementation of mutants by ABA indicated that the ABA signal transduction pathway was not significantly affected in the lto1-2 mutant. Taken together, these results suggest that LTO1 is involved in ABA-mediated response to osmotic stress, possibly by affecting the biosynthesis of endogenous ABA.
authors.affiliation: College of Life Science, Shandong Agricultural University, Taian, 271018, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Peng
authors.forename: Zhi-Bo
authors.initials: ZB
authors.lastname: Yu
authors.forename: Jia-Jia
authors.initials: JJ
authors.lastname: Du
authors.forename: Jia-Ning
authors.initials: JN
authors.lastname: Xu
authors.forename: Xiao-Yun
authors.initials: XY
authors.lastname: Wang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017302:Annexins / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000378:metabolism*; D057773:Cold Shock Proteins and Peptides / Q000378:metabolism; D009997:Osmotic Pressure; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional; D020524:Thylakoids / Q000378:metabolism*; D064417:Vitamin K Epoxide Reductases / Q000235:genetics / Q000378:metabolism*
chemical_list: D017302:Annexins; D029681:Arabidopsis Proteins; D057773:Cold Shock Proteins and Peptides; C000595439:RD29B protein, Arabidopsis; D017382:Reactive Oxygen Species; D000040:Abscisic Acid; C504971:annexin 1, Arabidopsis; D064417:Vitamin K Epoxide Reductases; C000604454:lumen thiol oxidoreductase 1, Arabidopsis