膜脂过氧化与水稻对稻瘟病抗性的关系

Relationship between lipid peroxidation and rice resistance to Magnaporthe grisea

喷雾接种稻瘟菌后测定了水稻幼苗叶片内丙二醛含量及相对电导率的变化 .结果表明 :表现非亲和反应的水稻 H8R叶片中丙二醛含量及相对电导率在接种后 18h开始增加 ,均于 30 h和 6 0 h形成一小一大的峰值 ,这正是水稻叶片过敏性坏死斑出现到形成时 ;而在亲和反应的 H8S叶片中二者均只在接种后 4 8～ 72 h间有一个相对升高期 ,其增幅均低于非亲和反应 .同时证明 ,接种后 30 h,H8R叶片中亚麻酸和亚油酸含量明显降低 ,而在亲和反应中基本不变 .非亲和反应的水稻叶片中脂氧合酶活性在接种后 18h开始上升 ,在 2 4 h和 72 h分别出现两个峰值 ;亲和反应中该酶活性在互作后期 (6 0～ 72 h)略有增加 .这些结果说明脂氧合酶活性变化与膜脂过氧化表现明显的时间动态相关 ,膜脂过氧化引起的电解质渗漏是过敏性反应的主要生理机制之一 .

A pair of near isogenic lines (NIL) of rice, H8R and H8S, was inoculated with Magnaporthe grisea at 5 leaf stage, resulting incompatible and compatible reactions, respectively. Both malondiadehyde levels and relative conductivity in the leaves of NIL H8R significantly increased from 18 h after the inoculation and reached their maximums at 30 h and 60 h, just corresponding to development of visible necrosis on the leaves. In the NIL H8S leaves with compatible reaction, however, they increased during 48 h to 72 h after inoculation. Their maximum levels were much lower than those in the incompatible NIL H8R. Moreover, the gas chromatography analysis of the membrane lipids from leaves at 30 h after inoculation showed decreased levels of the linoleic acid and linolenic acid in the incompatible host, but no significant change of those in the compatible host. The activities of lipoxygenase (LOX) began to increase at 18 h after inoculation in the compatible host and reached their maximums at 24 h and 72 h. In the compatible host, however, the activities increased at the later stage (from 60 h to 72 h) after inoculation. These results suggested that changes of LOX activities in the inoculated leaves had some correlation with the progress of lipid peroxidation, and that electrolyte leakage resulted from lipid peroxidation would be one of the physiological mechanisms for hypersensitive response.