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

以突变的水稻植株为材料，研究了稻瘟病菌小种间的特异性。用稻瘟病菌孢子侵染水稻突变株关口朝日时，稻瘟病菌的病斑形成依赖于光，这种独特的病斑形成可被光和蛋白质合成抑制剂DCMU和放线菌亚胺处理所抑制。稻瘟病菌将一种毒素(S)释放到孢子萌发液中，使非病原菌链格孢菌侵染寄主植物组织。通过超微结构观察和形态计量学测量，研究了S毒素在建立真菌与植物基本亲和性中的作用。毒素诱导的超微结构改变首先是毒素暴露后1小时线粒体基质丢失和线粒体脊断裂。然而，毒素处理后线粒体修饰频率并不随时间的延长而增加。其他细胞器即使在t…中也是正常的。更多的是他后期的毒素治疗。无论光照条件如何，这些现象在关口朝日和朝日叶片中均可观察到。当研究S毒素对寄主植物(水稻和大麦)和非寄主植物(指谷)的影响时，首先引起水稻和大麦植株的变化是线粒体基质丢失和线粒体脊断裂。在毒素暴露后1小时观察到线粒体膜的这些改变。然而，毒素处理后线粒体修饰的频率并没有随着时间的延长而增加。其他细胞器即使在毒素处理的后期也是正常的。在寄主植物大麦和水稻的三个部位(表皮细胞、叶肉细胞和韧皮部细胞)中观察到了这种现象。而在非寄主植物指谷的叶片中，未观察到S毒素的作用。此外，亲和和不亲和品种的表皮细胞在接种稻瘟病菌孢子12小时后都观察到线粒体的修饰。这些结果表明，S毒素诱导的线粒体修饰是稻瘟病菌与寄主植物在物种水平上建立基本亲和性的重要事件。较少

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