【摘要】 玉米小斑病菌T小种能产生致病毒素,毒素对感病品系叶肉细胞原生质体能产生强烈的毒害作用,并刺激PAL活性增高。T小种毒素对T细胞质雄性不育系有强烈的选择特异性,仅在高浓度时才对正常细胞质保持系有轻微毒害。玉米大斑病菌产生的毒素其作用与小斑病菌T小种毒素相反,即对正常细胞质保持系有选择特异性,但强度较弱。红光对T细胞质雄性不育系和正常细胞质保持系玉米植株刺激PAL活性增高的程度无甚差异。毒素和红光刺激玉米PAL活性增高的机理是不同的。PAL活性的增高与玉米抗病性成负相关。更多还原

【Abstract】 The study of maize leaf blight is of economic and scientific importance. Thepresent paper is on the effects of toxins produced by Helminthosporium maydis raceT and Helminthosporium turcicum on PAL, which is a determinant enzyme in se-condary metabolism and is closely related to disease resistance.In the field, H. maydic race T only infects maize var. T4343 which containsthe T type male sterile cytoplasm, and the toxin produced is highly specific andonly injures protoplasts of var. T4343, but not N type maintenance line cyto-plasm of var. N4343.H turcicum is the contrary to H. maydis race T. It infects N4343 seriously inthe field, and filtrate of its culture seriously injures protoplasts of N4343 only, where-as protoplasts from T4343 is injured but slightly. Similarly, the preparation totoxin from H maydis race T stimulates the activity of PAL sharply in var. T4343,but not in var. N4343, while the toxin from H.turcicum stimulates the activity ofPAL in N4343, but not in T4343.But, when seedling of var. T4343 and var. N4343 grown in the dark are ex-posed to red light, to bring about an increase of PAL activities, no difference hasbeen observed. Thus it is considered that the increase of PAL activities inducedby red light and by toxins is effected through different mechanisms.更多还原