油菜根肿病菌的形态和休眠孢子的生物学特性

Morphology of Plasmodiophora brassicae and Biological Characteristic of the Pathogenic Resting Spores in Rapeseed

【目的】比较油菜根肿病菌与十字花科蔬菜根肿病菌的形态是否存在差异。研究油菜根肿病菌休眠孢子的生物学特性,为防治油菜根肿病提供依据。【方法】应用扫描电镜观察油菜根肿病菌的形态特征和休眠孢子至管腔的形态演变过程。采用地衣红染色,观测不同根分泌物和条件对休眠孢子萌发的影响。【结果】休眠孢子近球形,有乳突,直径为1.9～4.3μm(平均3.5μm),大于甘蓝根肿菌休眠孢子(2.5μm);透射电镜下游动孢子近球形、肾形或椭圆形,直径为1.6～3.5μm(平均2.8μm),同侧生不等长尾鞭式双鞭毛。休眠孢子萌发形成游动孢子、休止孢、休止孢再生出侵入结构管腔。休眠孢子萌发的最适温度是24℃,最适pH值是6.3,腐烂处理促进休眠孢子萌发,光抑制休眠孢子萌发,休眠孢子在过滤灭菌的根分泌物中萌发率最高为62.50%。致死温度为48℃。【结论】油菜根肿病菌与十字花科甘蓝根肿病菌休眠孢子大小有明显差异,观察到休眠孢子至管腔的过程。油菜根肿菌休眠孢子的萌发条件与该病发生条件相一致。

[Objective] To compare differentiation ofPlasmodiophora brassicae in the morphology between the clubroot of rapeseed and clubroot of cabbage and studied on biological characteristic of the pathogenic resting spores so that we could control the disease. [Method] Looked into morphology of Plasmodiophora brassicae from resting spores to tube antrum in scanning electron microscope and effect of different root secretion and condition to the germination of resting spores with dying of Orcein. [Result] The resting spores were nearly spherical, not slippery and mamillated on the wall in scanning electron microscope, their diameters range from 1.9 to 4.3μm（ the mean 3.5μm）. The primary zoospores with unequal length biflagella were in nearly spherical, or nephroid, or oval shape in transmission electron microscope, and their size varied widely from 1.6 to 3.5μm（ the mean 2.8μm）. It was observed that the changing course of the resting spores turned into the primary zoospores, the silent spores in orderly, and then one silent spore growed out a tube antrum of infection structure. The optimum temperature for the germination of resting spores was 24℃, the optimum pH was 6.3. Treatment of rotted clubs was helpful to enhance the germinated rate. The visible light inhibited the germination of the resting spores. The highest germinated rate for the resting spores was 62.50% in the root exudates. The thermal death point of he resting spores was 48℃. [ Conclusion ]There were obvious diference in size of the resting spores between rapeseed and cabbage of clubroot. Became conscious of the course from resting spores to tube antrum. The conditions for germination of the resting spores are accordant with the disease＇s generant condictions.