宁夏地区欧李根癌病病原菌鉴定及防治药剂筛选

Identification of Causal Agent of Cerasus humilis Crown Gall Disease in Ningxia Region and Screening of Control Agents

对宁夏地区欧李(Cerasus humilis(Bge.) Sok.)根癌病病原菌开展鉴定并筛选防治药剂。采用组织分离法进行病原菌的分离,以胡萝卜和向日葵为指示植物按柯赫氏法则确定其致病性,经形态学、生理生化性质和16S rDNA序列分析进行分类鉴定。采用滤纸片抑菌圈法对8种低毒杀菌剂开展毒力测定,筛选出对病原菌有较强抑菌效果的药剂,以向日葵为指示植物进行防治效果验证。结果表明:从欧李根癌组织中分离获得的ATJ1菌株,可以使胡萝卜盘和向日葵接种部位出现明显的增生,具有致病性。ATJ1菌株分类鉴定为根癌土壤杆菌(Agrobacterium tumefaciens)生物I型。在室内药剂筛选中,四霉素和乙蒜素的防治效果最好,400倍稀释液的抑菌率分别为83.80%和72.55%,ρ(EC_(50))分别为5.13和985.75 mg/L。在盆栽试验中,四霉素和乙蒜素对病原菌ATJ1均具有较强的抑菌效果,向日葵接种部位未发病,但是高质量浓度药剂会导致药害。因此,低质量浓度(稀释倍数≥1 200倍)的四霉素或乙蒜素适用于欧李根癌土壤杆菌的防治。

The experiment was conducted to identify and screen microbicides against crown gall of Cerasus humilis in Ningxia. The pathogen was isolated using tissue isolation method. The pathogenicity of carrot and sunflower was determined according to robertkoch’s law using carrot and sunflower as indicator plants. The morphological, physiological and biochemical properties were analyzed, and 16S rDNA sequence analysis was used for classification and identification. The toxicity of nine low-toxic microbicides was tested by using the inhibition zone method of filter paper, and the microbicides with strong inhibitory effect on the pathogenic bacteria were screened out, and the control effect was verified with sunflower as the indicator plant. The results showed that ATJ1 strain isolated from the root cancer tissue of C. humilis could obviously proliferate on the inoculation site of carrot disk and sunflower, and was pathogenic. The ATJ1 strain was classified as Agrobacterium tumefaciens biotype I. In the indoor agent screening, tetramycin and ethephon had the best control effect, with 83.80% and 72.55% inhibition at 400×dilution, and EC_(50)of 5.13 and 985.75 mg/L, respectively. In pot experiments, both tetramycin and ethylicin had strong antibacterial effects on the pathogen ATJ1. No disease occurred at the inoculation site of sunflower, but high concentration of the drug would lead to phytotoxicity. Therefore, low concentrations(≥1 200×dilution) of tetramycin or ethylicin are suitable for the control of Agrobacterium tumefaciens in C. humilis.