title: A two-component histidine kinase of the rice blast fungus is involved in osmotic stress response and fungicide action.
abstract: We isolated and characterized a histidine kinase gene (HIK1) from the rice blast fungus, Pyricularia oryzae (Magnaporthe grisea). The deduced amino acid sequence of HIK1 showed highest similarity (85.7%) to a hybrid-type histidine kinase, Os-1/Nik-1 of Neurospora crassa. Disruption of HIK1 caused no defect in cell growth on normal media and in pathogenicity to rice plants. The Deltahik1 strain acquired resistance to three groups of fungicides (phenylpyrroles, dicarboximides, and aromatic hydrocarbons) similar to os-1 mutants of N. crassa. The Deltahik1 strain showed increased sensitivity to high concentrations of sugars although its salt sensitivity was not elevated, suggesting that the rice blast fungus can distinguish osmostresses caused by high sugar concentrations and high salt concentrations. In contrast, os-1 mutants of N. crassa are sensitive to high concentrations of both salts and sugars. These findings suggest that P. oryzae and N. crassa partially differ in their os (osmosensitive) signal transduction pathway.
authors.affiliation: RIKEN (Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. tmotoyam@riken.jp
authors.forename: Takayuki
authors.initials: T
authors.lastname: Motoyama
authors.forename: Kaori
authors.initials: K
authors.lastname: Kadokura
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ohira
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ichiishi
authors.forename: Makoto
authors.initials: M
authors.lastname: Fujimura
authors.forename: Isamu
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kudo
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal / Q000235:genetics; D003001:Cloning, Molecular; D017931:DNA Primers; D017353:Gene Deletion; D000071677:Histidine Kinase; D020082:Magnaporthe / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D008969:Molecular Sequence Data; D012275:Oryza / Q000382:microbiology; D018384:Oxidative Stress / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D011494:Protein Kinases; D000071677:Histidine Kinase