Expression of a bacterial chitosanase in rice plants improves disease resistance to the rice blast fungus Magnaporthe oryzae
Expression of a bacterial chitosanase in rice plants improves disease resistance to the rice blast fungus Magnaporthe oryzae
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DOI：
10.1007/s00299-011-1179-7
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发表时间：
2012-04-01
影响因子：
6.2
通讯作者：
Nishizawa, Yoko
中科院分区：
文献类型：
--
作者：
Kouzai, Yusuke;Mochizuki, Susumu;Nishizawa, Yoko
植物真菌病原菌在侵染过程中改变细胞壁成分以避免被宿主裂解酶降解，将细胞壁几丁质转化为壳聚糖可能是病原菌的侵染策略之一。因此，将壳聚糖降解活性引入植物中有望提高真菌病害抗性。壳聚糖酶存在于细菌和真菌中，但在高等植物中尚未发现。在这里，我们证明了壳聚糖酶，Cho 1，从芽孢杆菌的环状MH-K1对稻瘟病菌的抗真菌活性。cho 1基因的导入赋予水稻细胞壳聚糖酶活性。将Cho 1定位于质外体的转基因水稻植株对稻瘟病菌的抗性增强。在感染的表皮细胞中，伴随着过氧化氢生成的增加。这些结果表明壳聚糖存在于M.在感染过程中的抗真菌性和抗病性的增强是由于分泌Cho 1的抗真菌活性和宿主防御反应的激发增加。
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.