title: Suppression of Arabidopsis AtPUB30 resulted in increased tolerance to salt stress during germination.
abstract: The Arabidopsis U-box E3 Ub ligase AtPUB30 participates in the salt stress tolerance as a negative factor in an ABA-independent manner during germination. Based on the in silico expression data, the U-box protein 30 (AtPUB30) from Arabidopsis thaliana was identified as a gene that responds to salt stress. The deduced AtPUB30 protein consists of 448 amino acids with a single U-box motif and five ARM-repeat domains. An in vitro self-ubiquitination assay demonstrated that bacterially expressed AtPUB30 exhibited E3 ubiquitin (Ub) ligase activity and that the U-box domain was essential for the activity. Real-time qRT-PCR and promoter-GUS analyses showed that AtPUB30 was induced by high salinity, but not by drought, cold, or abscisic acid (ABA), in roots but not in shoots. These results suggest that AtPUB30 is an Arabidopsis U-box E3 Ub ligase, the expression of which is selectively enhanced by salt stress in roots. T-DNA-inserted loss-of-function atpub30 mutant plants (atpub30-1 and atpub30-2) were more tolerant to salt stress in the germination stage, as identified by radicle emergence, cotyledon opening, and more vigorous early root growth relative to wild-type plants. Thus, it is likely that AtPUB30 plays a negative role in high salinity tolerance in the germination process. Wild type and mutant plants displayed very similar germination rates when treated with ABA, suggesting that the action of AtPUB30 in the germination stage is ABA independent. The post-germination growth of NaCl-stressed wild type and mutant plants were indistinguishable. Overall, our data suggest that the Arabidopsis U-box E3 Ub ligase AtPUB30 participates in the salt stress tolerance as a negative factor in the germination stage in root tissues.
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, 120-749, Korea.
authors.forename: Jae Hwan
authors.initials: JH
authors.lastname: Hwang
authors.forename: Dong Hye
authors.initials: DH
authors.lastname: Seo
authors.forename: Bin Goo
authors.initials: BG
authors.lastname: Kang
authors.forename: June M
authors.initials: JM
authors.lastname: Kwak
authors.forename: Woo Taek
authors.initials: WT
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D017930:Genes, Reporter; D018525:Germination; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010641:Phenotype; D010802:Phylogeny; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D055049:Salt Tolerance; D016415:Sequence Alignment; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D013489:Suppression, Genetic; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D012965:Sodium Chloride; D044767:Ubiquitin-Protein Ligases; C000602138:PUB30 protein, Arabidopsis