title: Expression of a bacterial chitosanase in rice plants improves disease resistance to the rice blast fungus Magnaporthe oryzae.
abstract: Plant fungal pathogens change their cell wall components during the infection process to avoid degradation by host lytic enzymes, and conversion of the cell wall chitin to chitosan is likely to be one infection strategy of pathogens. Thus, introduction of chitosan-degradation activity into plants is expected to improve fungal disease resistance. Chitosanase has been found in bacteria and fungi, but not in higher plants. Here, we demonstrate that chitosanase, Cho1, from Bacillus circulans MH-K1 has antifungal activity against the rice blast fungus Magnaporthe oryzae. Introduction of the cho1 gene conferred chitosanase activity to rice cells. Transgenic rice plants expressing Cho1 designed to be localized in the apoplast showed increased resistance to M. oryzae accompanied by increased generation of hydrogen peroxide in the infected epidermal cells. These results strongly suggest that chitosan exists in the enzyme-accessible surface of M. oryzae during the infection process and that the enhancement of disease resistance is attributable to the antifungal activity of the secreted Cho1 and to increased elicitation of the host defense response.
authors: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
authors: Yusuke
authors: Y
authors: Kouzai
authors: Susumu
authors: S
authors: Mochizuki
authors: Akihiro
authors: A
authors: Saito
authors: Akikazu
authors: A
authors: Ando
authors: Eiichi
authors: E
authors: Minami
authors: Yoko
authors: Y
authors: Nishizawa
mesh_terms: D001407:Bacillus / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002686:Chitin / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006026:Glycoside Hydrolases / Q000235:genetics*; D020082:Magnaporthe / Q000276:immunology / Q000502:physiology*; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D019441:Plant Epidermis; D018515:Plant Leaves; D030821:Plants, Genetically Modified; D019076:Transgenes
chemical_list: D001426:Bacterial Proteins; D002686:Chitin; D006026:Glycoside Hydrolases; C019868:chitosanase