title: RING Type E3 Ligase CaAIR1 in Pepper Acts in the Regulation of ABA Signaling and Drought Stress Response.
abstract: Several E3 ubiquitin ligases have been associated with the response to abiotic and biotic stresses in higher plants. Here, we report that the hot pepper (Capsicum annuum) ABA-Insensitive RING protein 1 gene (CaAIR1) is essential for a hypersensitive response to drought stress. CaAIR1 contains a C3HC4-type RING finger motif, which plays a role for attachment of ubiquitins to the target protein, and a putative transmembrane domain. The expression levels of CaAIR1 are up-regulated in pepper leaves by ABA treatments, drought and NaCl, suggesting its role in the response to abiotic stress. Our analysis showed that CaAIR1 displays self-ubiquitination and is localized in the nucleus. We generated CaAIR1-silenced peppers via virus-induced gene silencing (VIGS) and CaAIR1-overexpressing (OX) transgenic Arabidopsis plants to evaluate their responses to ABA and drought. VIGS of CaAIR1 in pepper plants conferred an enhanced tolerance to drought stress, which was accompanied by low levels of transpirational water loss in the drought-treated leaves. CaAIR1-OX plants displayed an impaired sensitivity to ABA during seed germination, seedling and adult stages. Moreover, these plants showed enhanced sensitivity to drought stress because of reduced stomatal closure and decreased expression of stress-responsive genes. Thus, our data indicate that CaAIR1 is a negative regulator of the ABA-mediated drought stress tolerance mechanism.
authors.affiliation: Department of Life Science (BK21 program), Chung-Ang University, Seoul 156-756 Republic of Korea These authors contributed equally to this work.
authors.forename: Chanmi
authors.initials: C
authors.lastname: Park
authors.affiliation: Department of Life Science (BK21 program), Chung-Ang University, Seoul 156-756 Republic of Korea These authors contributed equally to this work.
authors.forename: Chae Woo
authors.initials: CW
authors.lastname: Lim
authors.affiliation: Department of Life Science (BK21 program), Chung-Ang University, Seoul 156-756 Republic of Korea.
authors.forename: Woonhee
authors.initials: W
authors.lastname: Baek
authors.affiliation: Department of Life Science (BK21 program), Chung-Ang University, Seoul 156-756 Republic of Korea sclee1972@cau.ac.kr.
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Lee
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000222:Adaptation, Physiological / Q000187:drug effects; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002212:Capsicum / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D055864:Droughts; D020868:Gene Silencing / Q000187:drug effects; D017343:Genes, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D060888:Real-Time Polymerase Chain Reaction; D054712:Salinity; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D010940:Plant Proteins; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid; D044767:Ubiquitin-Protein Ligases
keywords: Abscisic acid; CaAIR1; Drought stress; Pepper; Ubiquitination; Virus-induced gene silencing