禾谷丝核菌拮抗细菌的鉴定及其拮抗产物分析

 小麦纹枯病是长江中下游麦区重要的土传病害。明确小麦根际拮抗细菌种类和拮抗机理对小麦纹枯病生物防治具有重要意义。从江苏省姜堰市小麦根际分离到拮抗细菌A6、A12、B37、B40、B41和B42。通过生理生化测定和16SrDNA同源序列比对分析,这些菌株都为荧光假单胞杆菌。在温室条件下进行种子处理,这些菌株对小麦纹枯菌都有一定的控制作用,其中菌株A6、B41和B42的控病作用明显,菌株B42对小麦纹枯病的控制效果最好,温室防效达71.67%。基因检测和次生代谢物分析的结果表明:6个菌株都不产生2,4-二乙酰基间苯三酚和吩嗪,菌株A12、B37和B42含有与吡咯菌素合成相关的基因PrnD,在菌株B37中还检测到合成基因PrnC;菌株A12、B37和B42产生嗜铁素;除了菌株A6和B37,其余菌株都产生蛋白酶;所有菌株都不产生几丁质酶。

Identification and characterization of bacteria antagonistic to Rhizoctonia cerealis

Wheat sharp eye-spot,caused by Rhizoctonia cerealis,is an important soil-borne wheat disease in the middle and lower valley of Yangtze River.It is important to determine the category of wheat rhizosphere bacteria,characterize their biological control mechanism and effects on wheat sharp eye-spot.Bacterial strains A6,A12,B37,B40,B41 and B42 were isolated from wheat rhizosphere in Jiangyan city of Jiangsu province.These strains were determined as Pseudomonas fluorescens by analysis of their 16S rDNA sequences,physiological and chemical characters.In greenhouse,all the 6 bacterial strains decreased wheat sharp eye-spot disease index,the control efficiency of strain B42 reached to 71.67%.The analysis of secondary metabolite indicated that all the 6 strains produced neither 2,4-diacetylphloroglucinol nor phenazine.Pyrrolnitrin production related gene PrnD was found in the strain A12,B37 and B42.In strain B37,another Pyrrolnitrin production related gene PrnC was also detected.A12,B37and B42 produced siderophore,A12,B40,B41 and B42 produced proteinase,and none of the strains produced chitinase.