Elucidation of race-cultivar specificity in blast by using mutant rice plants.

以水稻突变株为研究对象，研究了稻瘟病真菌品种间的特异性。当突变水稻种植时，cv。用稻瘟病病菌孢子接种Sekiguchi-asahi后，Sekiguchi病斑在叶片上形成光依赖性，这种独特的病斑形成被光合成和蛋白质合成抑制剂DCMU和环己亚胺预处理抑制。稻瘟病病菌向孢子萌发液中释放一种毒素，使非病原体交替稻瘟病菌感染寄主植物组织。采用超微结构观察和形态计量学方法研究了一种毒素在真菌与植物建立基本亲和性中的作用。中毒后第一个超微结构变化是线粒体基质的丢失和线粒体嵴的破坏。然而，在毒素处理后，线粒体修饰的频率并没有随着时间的增加而增加。在毒素处理后期，其他细胞器基本正常。这些现象在不同光照条件下的“关口-朝日”和“朝日”叶片中均有观察到。当研究毒素对寄主植物（水稻和大麦）和非寄主植物（谷子）的影响时，毒素引起的水稻和大麦植物的第一个变化是线粒体基质的丧失和线粒体嵴的破坏。在毒素暴露1小时后，线粒体中观察到这些变化。然而，毒素处理后，线粒体修饰的频率不随时间增加。其他细胞器即使在毒素处理后期也正常。在寄主植物大麦和水稻的表皮、叶肉和韧皮部细胞三个部位均观察到这种现象。然而，毒素对非寄主植物谷子的叶片没有影响。此外，在接种稻瘟病菌孢子12小时后，亲和性和非亲和性品种的表皮细胞均观察到线粒体修饰。这些结果表明，由毒素诱导的线粒体修饰是稻瘟杆菌在种水平上与寄主植物建立基本亲和性的必要事件。少

The specificity between fungal race-plant cultivars in blast was studied by using mutant rice plants. When mutant rice plant, cv.Sekiguchi-asahi, was inoculated with Magnaporthe grisea spores, the Sekiguchi lesion were light-dependently formed on the leaves, This unique lesion formation was suppressed by pre-treatment with photo- and protein-synthesic inhibitors, DCMU and cycloheximide. Magnaporthe grisea releases a toxin(s) into the spore germination fluid, which allow anon-pathogen, Alternaria alternata, to infect host plant tissues. The role of a toxin(s) on establishment of basic compatibility between fungus and plant was investigated by ultrastructural observation and morphometric measurement. The first toxin-induced changes in ultrastructure were the losses of mitochondrial matrix and the disruption of mitochondrial cristae 1hr after toxin exposure. However, frequency of modified mitochondria did not increase with time after toxin treatment. Other organelles were normal even in t … More he late stage of the toxin treatment. These phenomena were observed in both Sekiguchi-asahi and Asahi leaves regardless of light condition. When the effects of the toxin(s) on host plants (rice and barley) and non-host plant (finger millet) were examined, the first toxin-induced changes in rice and barley plants were the loss of the mitochondrial matrix and the disruption of mitochondrial cristae. These modifications in mitochonria were observed 1 hr after toxin exposure. However, the frequency of modified mitochondria did not increase with time after toxin treatment. Other organelles were normal even in a late stage of the toxin treatment. Such phenomena were observed in three sites (epidermal, mesophyll and phloem cells) of host plants, barley and rice. However, the effects of toxin(s) were not observed in leaves of non-host plant, finger millet. Further, mitochondrial modifications were observed in both epidermal cells of compatible and incompatible cultivars 12hr after inoculation of M.grisea spores. These results indicated that mitochondrial modification induced by the toxin(s) was an essential event for M.grisea to establish basic compatibility with host plants at species level. Less