Expression of a bacterial chitosanase in rice plants improves disease resistance to the rice blast fungus Magnaporthe oryzae

Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Plant Cell Reports (Impact Factor: 3.07). 11/2011; 31(4):629-36. DOI: 10.1007/s00299-011-1179-7
Source: PubMed


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.

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Available from: Yoko Nishizawa, Oct 02, 2014
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    • "To quantify M. oryzae biomass, M. oryzae 28S ribosomal DNA (rDNA) in the inoculated leaf blades was measured as per the method described by Kishimoto et al. (2010). The hyphal growth and detection of H 2 O 2 accumulation in the epidermal cells of leaf sheaths were evaluated for two independent lines by the previously described method (Kouzai et al. 2012; Tanabe et al. 2009). "
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