水稻稻曲病菌的分离鉴定及室内毒力测定

Isolation,Identification and Fungicide Toxicity of Ustilaginoidea virens

为优化稻绿核菌的分离方法,筛选防控稻曲病的有效药剂,采用孢子敲落法和火焰灼烧法分别分离不同成熟度的稻曲球,从形态学、致病性、rDNA-ITS序列等方面对HP-7菌株进行鉴定,并通过菌丝生长抑制法测定了HP-7菌株对7种杀菌剂的敏感性。结果表明,采用孢子敲落法分离鲜黄色稻曲球成功率最高,达98.33%,将HP-7菌株的rDNA-ITS序列在NCBI上进行BLAST比对,菌株HP-7与稻绿核菌相似度达99%,结合形态学特征分析确定HP-7为稻绿核菌。离体试验表明,戊唑醇和嘧菌酯对稻绿核菌的菌丝生长抑制作用最强,其EC_(50)值分别为0.109 1、0.158 5mg·L^(-1)。其结果可为稻绿核菌的分离鉴定及稻曲病防控提供理论参考。

Two methods for isolating HP-7 （Ustilaginoidea virens） and 7 fungicides for controlling the false smut disease on rice caused by the pathogen were compared. Fungal spores at different maturation stages were separated by means of shaking or flame burning. HP-7 was verified by its morphology, pathogenicity, and rDNA-ITS sequences. The sensitivity of HP-7 toward and toxicity on the fungi by the fungicides were determined based on the fungal mycelium growth under treatment. It was found that the successful rate in separating the fresh yellow chiamydospores by shaking was up to 98.33%, which was better than the flaming method. The rDNA-ITS sequences of HP-7 were submitted to NCBI for a BLAST analysis that showed a 99% homogeny with U. virens. Combining that result with the morphological observations, HP-7 was verified to be the pathogen that caused the rice false smut. Among the fungicides tested, tebuconazole and azoxystrobin exhibited the highest inhibition rates on HP-7, with EC50 at 0. 109 1 and 0. 158 5 mg · L^-1 , respectively. It appeared that an effective spore separation method was identified, and the positive identification and appropriate selection on fungicide for effective control of the false smut disease on rice crops were obtained.