【作者】 张华东；

【导师】 徐敬友；

【作者基本信息】 扬州大学 ， 作物遗传育种， 2003， 硕士

【摘要】 本试验用改良Richard培养液培养立枯丝核菌(Rhizoctonia solani)，滤液经活性炭吸附，甲醇洗脱，旋转蒸发得到粗毒素。对粗毒素进行生物活性检测，发现粗毒素在水稻叶片上能形成水稻纹枯病的典型症状，并可抑制水稻种子胚根的生长，致使水稻幼苗失绿萎蔫。毒素的有效稀释浓度试验结果显示，粗毒素浓度越高毒性效果越强，当粗毒素稀释到200倍时仍具有一定的生物活性。 研究表明，立枯丝核菌产毒最佳条件：培养液为改良Richard培养液，培养时间为15～20天，培养温度为25～30℃，培养液pH为7左右，不需要光照，每天人工振荡2次。 立枯丝核菌不同菌株产生毒素的能力有明显差异。通过比较发现，菌株的产毒能力与其对水稻植株的致病能力存在显著正相关，相关系数为0.8255。这说明立枯丝核菌毒素在病菌致病过程中发挥着重要作用。 分别用立枯丝核菌粗毒素处理水稻抗感品种种子，发现抗病品种(特青和J-85)胚根对毒素的耐力较强，生长抑制率仅为25.26％和29.53％，而感病品种(LMNT)种子几乎不能萌发，胚根生长抑制率达92.19％。此外，抗病品种幼苗在毒素液中处理12h后没有变化，而感病品种幼苗叶片则发生卷曲萎蔫。因此，以立枯丝核菌粗毒素处理水稻种子和幼苗可初步鉴定品种对纹枯病的抗性。 立枯丝核菌和禾谷丝核菌(R.cerealis)及其粗毒素对水稻、玉米和小麦均有一定的致病作用。在水稻和玉米上，立枯丝核菌及其毒素的致病力略强于禾谷丝张华东:立枯丝核菌毒素的产生及与致病力的关系核菌及其毒素，但在小麦上，禾谷丝核菌及其毒素的致病力往往要强于立枯丝核菌及其毒素。更多还原

【Abstract】 the crude toxin of Rhizoctonia solani in improved Richard’s medium was extracted when the cultured filtrate was absorbed by active carbon with methanol as eluant and then the methanol was evaporated by rotavapor. The biological activity assay of the crude toxin showed that it could induce the characteristic symptom of rice sheath blight and inhibit the growth of rice radicle and make the seedling wilting. The experimental results revealed that the higher the concentration was, the more virulent the crude toxin was. When the crude toxin was 200 times diluted, it still had some biological activity.The culture condition for the production of Rhizoctonia solani toxin was studied. It was appropriate for the toxin production as follows: The optimum medium was improved Richard’s medium, in which pH value was 7. The strains was cultured for15-20 days at 25~30℃, with darkness and shake in hand two times every day.It was found that the ability of toxin production was obviously different among the isolates. There was a significantly positive correlation between the ability of toxin production and the virulence of R. solani with r value of 0.8255, which indicated that the toxin of R. solani played an important role in the infection process.The seeds of rice varieties with different resistances were treated with the crude toxinof R. solani. It was found that the radicles of resistant rice varieties (TEQIN and J-85) were more tolerant to the toxin than those of the susceptible variety (LMNT). The seeds of LMNT could not nearly germinate and its leaves became curling and wilting after the treatment of R. solani toxin. So the resistances of rice varieties could be primarily identified by the treatment of rice radicles and seedlings with the crude toxin of R. solani.The inoculation tests showed that all isolates of R. solani and R. cerealis and their crude toxins had virulence on the plants of rice, maize and wheat. R. solani and its crude toxin was more virulent on rice and maize than R. cerealis and its crude toxin. On the contrary, R. cerealis and its crude toxin was more virulent on wheat than R. solani and its crude toxin.更多还原