Abstract: Phenotypical,cytological and molecular responses of rice to the fungus Magnaporthe grisea within 24 h after inoculation were studied by using the lesion mimic mutant LmmKaty and its parent Katy,double haploid rice lines YT14 and YT16 as materials.The variety Katy is susceptible to several virulent M.grisea isolates,and a Sekiguchi like-lesion mimic mutant of Katy(LmmKaty)showed enhanced resistance to these isolates.Autofluorescence was visible under ultraviolet light 20-24 h after localized inoculation in the incompatible interaction,whereas,autofluorescence was not evident in the compatible interaction.The results indicated that rapid cell death was involved in a mechanism of LmmKaty to restrict pathogen invasion.Northern blotting results showed that the rapid accumulation of defense related gene transcripts,phenylalanine ammonia lyase and β-glucanase,was observed beginning at 6 h after inoculation and was obvious at 16-24 h after inoculation in the incompatible interaction.Rapid transcript accumulation of PR-1 and chitinase had occurred 24 h after inoculation in the incompatible interaction.Accumulation of these transcripts was delayed in the compatible interaction.These results indicated that host active defense responses occured 24 h after pathogen inoculation and LmmKaty exhibited enhanced resistance to M.grisea.

Key words: rice(Oryza sativa), lesion mimic mutant, disease resistance, cytology, defense response, Magnaporthe grisea

摘要： 对水稻类病变坏死突变体 lmm1　(LmmKaty)与原亲本及双单倍体YT14和YT16接种稻瘟病菌24 h内的抗病反应、细胞学和分子作用机理进行了研究。人工接种实验表明，与原亲本相比，该突变体对稻瘟病菌具有更强的抗性。突变体接种20~24 h后,自动荧光检测到细胞死亡，而对照则未检测到。表明该突变体通过细胞程序性死亡阻止稻瘟病菌的蔓延，从而提高了抗病性。Northern blotting结果发现，抗病品系YT14中的防卫相关基因、苯丙氨酸解氨酶基因和β葡聚糖酶基因在人工接种稻瘟病菌6 h后开始表达，16~24 h后上述基因表达量快速增加；而病程相关蛋白基因 PR1和几丁质酶基因在人工接种稻瘟病菌24 h后才开始表达。与YT14相比，感病品系中上述基因的表达明显延迟。表明在人工接种稻瘟病菌24 h内水稻可启动抗病防卫反应，从而对稻瘟病菌产生抗性。

关键词: 水稻, 类病变突变体, 抗病性, 细胞学, 防卫反应, 稻瘟病菌