title: Arabidopsis hot2 encodes an endochitinase-like protein that is essential for tolerance to heat, salt and drought stresses.
abstract: The Arabidopsis hot2 mutant was originally identified based on its lack of thermotolerance, but pleiotropic abnormal phenotypes are also exhibited under normal conditions, including semi-dwarfism, ethylene overproduction and aberrant cell shape with incomplete cell walls. Here we present additional characterization of the hot2 mutant, and the map-based cloning of HOT2. Mutants of hot2 had an aberrant tolerance to salt and drought stresses, and accumulated high levels of Na(+) in cells under either normal or NaCl stress conditions. Expression of the stress-inducible COR15A and KIN1 gene in hot2 mutants in response to increased NaCl concentrations was normal. HOT2 encoded a chitinase-like protein (AtCTL1) that has not previously been shown to be involved in tolerance to salt stress. Ten-day-old seedlings of wild-type plants exhibited constitutive expression of the AtCTL1 transcript, the level of which was unaffected by treatment with NaCl, mannitol or mild heat. These observations provide genetic evidence that a chitinase-like protein prevents the overaccumulation of Na(+) ions, thereby contributing to the salt tolerance in Arabidopsis. A possible role for this chitinase-like protein in Arabidopsis tolerance to abiotic stress is discussed.
authors.affiliation: Division of Life and Genetic Engineering, College of Life and Environmental Sciences, Korea University, 1, 5-ka Anam-dong, Sungbuk-ku, Seoul, Korea.
authors.forename: YeRim
authors.initials: Y
authors.lastname: Kwon
authors.forename: Sun-Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Moon-Soo
authors.initials: MS
authors.lastname: Jung
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Kim
authors.forename: Jee-Eun
authors.initials: JE
authors.lastname: Oh
authors.forename: Hyun-Woo
authors.initials: HW
authors.lastname: Ju
authors.forename: Kang-Il
authors.initials: KI
authors.lastname: Kim
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Vierling
authors.forename: Hojoung
authors.initials: H
authors.lastname: Lee
authors.forename: Suk-Whan
authors.initials: SW
authors.lastname: Hong
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D002688:Chitinases / Q000235:genetics*; D004190:Disasters; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000235:genetics; D006358:Hot Temperature; D018021:Lithium Chloride / Q000494:pharmacology; D008353:Mannitol / Q000494:pharmacology; D008969:Molecular Sequence Data; D011189:Potassium Chloride / Q000494:pharmacology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; C116166:COR15 protein, Arabidopsis; C490208:KIN1 protein, Arabidopsis; D008353:Mannitol; D012965:Sodium Chloride; D011189:Potassium Chloride; C455513:CTL1 protein, Arabidopsis; D006026:Glycoside Hydrolases; D002688:Chitinases; D018021:Lithium Chloride