文献类型： 外文期刊
作者： Peng, YL 1 ; Chen, GH 1 ; He, M 1 ;
作者机构： 1.Sichuan Acad Agr Sci, Inst Plant Protect, Chengdu 610066, Peoples R China
关键词： hybrid rice;Magnaporthe grisea;resistance breakdown;possible mechanism
期刊名称：50TH INTERNATIONAL SYMPOSIUM ON CROP PROTECTION, PTS I-IV
ISSN： 0368-9697
年卷期： 1998 年 50 卷
页码：
收录情况： SCI
摘要： When a new resistant hybrid variety is cultivated virulent isolates of rice blast disease fungus (Magnaporthe grisea) have already existed with low frequencies on the susceptible conventional varieties, male sterile lines and other susceptible hybrid varieties Spores of both virulent and avirulent isolates can easily reach new resistant varieties. But virulent spores may fail to cause many symptoms due to the cross protection of much larger number of avirulent spores. In few cases, virulent spores may infect before avirulent spores arrive and produce lesions on new varieties. Spores from these lesions can not cause disease development on the new varieties because the neighboring plants are still challenged by the larger number of avirulent spores from susceptible source varieties. When the virulent spores hom the resistant varieties migrate back to source varieties, they can infect successfully and cause the rise in Virulent frequencies because no avirulent spores can migrate back. The recycling of the virulent spores between susceptible and resistant varieties on finally result in that the virulent frequencies reach to the required high level and the cross protection of avirulent spores loses effects. Then secondary infections can take place on the new varieties and the resistance is broken down.
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