芸薹根肿菌次生游动孢子侵染致病分析

为明确芸薹根肿菌Plasmodiophora brassicae Woron.在其它寄主中是否广泛存在无性短循环及次生游动孢子的侵染致病性,以不结球白菜为寄主培养3批幼苗(G1、G2和G3),用休眠孢子悬浮液接种G1,被侵染的G1接种G2,被侵染的G2接种G3,采用离心管水培法研究其侵染致病性。结果显示,无性短循环研究中,G1、G2和G3根毛均被侵染,除G3并株接种侵染率为33.33%外,其它处理侵染率均在50.00%以上,根毛里有明显的游动孢子囊;次生游动孢子能侵染不结球白菜的皮层组织,致使不结球白菜发病形成明显的肿根;G1、G2和G3水培发病率为20.00%、15.00%和6.00%,砂培发病率为22.50%、18.75%和7.50%;G3肿根病理切片中可观察到休眠孢子。表明芸薹根肿菌侵染不结球白菜时,其生活史中存在无性短循环,次生游动孢子具有侵染致病作用。

Pathogenic infection of the secondary zoospores of Plasmodiophora brassicae Woron

In this study, the asexual life cycle of Plasmodiophora brassicae Woron. in other hosts and the pathogenicity of secondary zoospore were investigated. Three groups of seedlings (G1, G2 and G3) were cultivated by using non-heading Chinese cabbage Siyueman as the host. With solution culture method, G1 was inoculated with resting spore suspension, and then the infected G1 was used to inoculate G2 and the infected G2 was used to inoculate G3. The results showed that the root hairs of G1, G2 and G3 were successfully infected, in which zoosporangia were obviously observed. The infection rates were all above 50.00%, except G3 (33.33%), which was planted together with G2. The cortical tissue of non-heading Chinese cabbage in G2 and G3 were infected with the secondary zoospores, which could cause clubroot. With water culture method, the incidence of G1, G2 and G3 was 20.00%, 15.00% and 6.00%, respectively. While with sand culture method, the incidence of G1, G2 and G3 was 22.50%, 18.75% and 7.50%, respectively. The resting spores were observed in the swollen roots of G3 based on pathological section. The results indicated that the asexual life cycle exactly existed in P. brassicae-infected non-heading Chinese cabbage, and the secondary zoospores played an important role in the pathogenicity.