【作者】 王力先；

【导师】 王永飞； 何晓明；

【作者基本信息】 暨南大学 ， 生物化学与分子生物学， 2007， 硕士

【摘要】 由真菌尖孢镰刀菌(Fusarium oxysporum f．sp．Schl)引起的枯萎病是造成华南地区节瓜减产的重要原因之一。目前尚无特别有效的防治药剂。因此，培育抗病品种是解决节瓜枯萎病问题的重要途径。本研究在获得抗毒素细胞系的基础上，对节瓜不同抗性品种在苗期进行枯萎病菌接种和镰刀菌酸毒素胁迫处理后的生理生化指标进行测定，同时用透射电镜对镰刀菌酸毒素胁迫后的超微结构进行研究。找出了与节瓜抗枯萎病相关的生理生化指标，并对节瓜的抗性机制进行了探讨。主要结果如下：1．发病前，感病品种和抗病品种叶片中叶绿素和游离脯氨酸含量无显著差异；抗病品种POD和PPO酶活高于感病品种，可溶性蛋白含量低于感病品种。枯萎病发病后，感病品种叶绿素和可溶性蛋白含量的下降幅度远远大于抗病品种；感病品种游离脯氨酸增加幅度高于抗病品种；抗病品种PPO酶活和POD酶活却远远高于感病品种，且一直维持在较高水平。因此，在节瓜苗期，其叶片内叶绿素含量、POD酶活、PPO酶活和可溶性蛋白含量可作为抗枯萎病的鉴定指标。2．在镰刀菌酸毒素胁迫下，感病品种叶绿素a和叶绿素b含量均出现先上升，后下降的变化趋势；游离脯氨酸含量急剧升高；POD酶活上升速度较慢，幅度也较小；PPO酶活升高速度快，幅度也较大：可溶性蛋白含量稳步提高，且一直高于抗病品种。抗病品种叶绿素a和叶绿素b含量则较稳定地维持在原有水平；游离脯氨酸含量平缓上升；POD酶活在前2h内急剧上升，之后维持在较高水平；PPO酶活上升速度则较慢；可溶性蛋白含量稳步提高，但一直低于感病品种。3．通过比较镰刀菌酸毒素和枯萎病病菌对节瓜苗期各生理生化指标的影响趋势发现，节瓜抗镰刀菌酸毒素与抗枯萎病之间有一定的相关性。4．毒素胁迫后，用透射电镜观察幼苗茎和子叶组织细胞的超微结构的变化，发现感病品种茎中叶绿体膜结构破坏，基粒片层肿胀；导管内有填充物：线粒体完好。子叶细胞中叶绿体叶内膜系统破坏，基粒片层排列紊乱；细胞壁发生扭曲变形，质壁分离严重；线粒体完好。抗病品种和抗镰刀菌酸毒素细胞变异系的茎和子叶细胞受毒素伤害都比较轻。更多还原

【Abstract】 Fusarium wilt caused by Fusarium oxysporum f. sp. Schl is a major factor limiting commercial Chieh-qua production in South China. At present there aren’t effective prophylaxis and remedy methods to control the desease; therefore, it’s important to breed desease-resistant cultivated varietis. Based on the previous study and successful establishment of toxin-resistant variety, a resistant cultivar A02, a susceptible cultivar A06 and a toxin-resistant variety LT seedlings were inoculated with Fusarium oxysporum, meanwhile, the three varieties seelding were treated with fusaric acid, then the dynamic change process of biochemical and physiological changes were determined, and the ultrastructure changes in stem tissue and eotyle tissue were investigated. So that the wilt resistance correlative physiologic and biochemical criterion were found out, and the antagonistic mechamism was studied. The main results were as follows:1. Before the wilt disease occured, there were not singnificant difference between the content of chlorophyll and dissociate proline in the susceptible type (S-type) and that of the resistant types (R-types); the activities of POD and PPO of the R-type were higher than that of the S-type; the content of soluble protein of the R-type were lower than that of the S-type. After the wilt disease come on, the S-type showed larger decreasint rates of cholrophyll and soluble protein than the R-types. The S-type showed higher increasing rate of proline content than the R-types. The activities of POD and PPO of the R-types were far higher than that of the S-type; furthermore, the activities of POD and PPO resistant variety maintained in the higher level even all the while. Therefore, at seedling stage of Chieh-qua, the contents of chlorophyll and soluble protein, the activities of POD and PPO in leaves can be as the critical indicators for screening wilt-resistance material.2. Under the condition of fusarium acid stress, the content of chlorophyll a and b of the S-tpye first increase and then decrease; the content of dissociate proline of the S-type increase rapidly; the S-tpe showed slow increase speed and lower increase extent of the activity of POD, but it showed fast increase speed in the activity of PPO. The content of chlorophyll a and b in eaves of the R-types maintain stably in the original level; the content of free proline of the R-types increased slowly; the activity of POD of the R-types increased rapidly within prior 2hs, and then maintain in the high level after that; the R-types showed slow increase speed and low increase extent of PPO activity; the content of soluble protein in leaves of three varieties rise steadily, and the content of soluble protein in leaves of the S-type was always higher than the R-types.3. The results of the comparison of the fusaric acid effect and the Fusarium oxysporum effect on the biochemical and physiological changes indicated that there was a certain correlation between the wilt-resistance and the toxin-resistance.4. Under the condition of fusarium acid stress for lh, ultrastructure studies were performed on the stem cells and the cotyledon cells. In stem cells of the S-type, endomembrane system of the chloroplast was destroyed, the grana lamellae be disorganized; tylose and gum could be observed in vessels; mitochondrion retain normal. In S-type cotyledon cells, chloroplast membrane was damaged, lamellae was in disorder, cell wall was out of shape and plasmolysis was observed, yet the mitochondrion retain normal. The effects of FA on S-type’s ultrastructure were heavier than on the R-type.更多还原