利用内生细菌防治小麦全蚀病的研究

Biological Control of Take-all of Wheat by Endophytic Bacteria

为了研究小麦内生细菌对小麦全蚀病的生物防治作用,采用表面消毒后涂布平板的方法,从来自河南麦区不同品种的82份健康小麦根系内分离获得530株小麦内生细菌。采用土壤浇灌法,于小麦活体上测定了内生细菌对小麦全蚀病的生防效果,从中获得15株可显著降低小麦全蚀病发病率和严重度的细菌。其中菌株WG-2和Y106对小麦全蚀病的防治效果分别达到83.25%和80.37%,显著优于常用化学农药三唑酮的防治效果(77.05%)。综合利用形态学、生理生化分析以及16SrDNA序列测定分析等方法对WG-2和Y106进行鉴定,结果表明,WG-2属于变形斑沙雷氏菌(Serratia proteamaculans),Y106属于枯草芽孢杆菌(Bacillus subtilis)。将WG-2和Y106 2个菌株混合,测定菌株混合后对小麦全蚀病的防治效果,发现菌株混合使用不能提高生防效果,2个菌株之间可能具有干扰作用。利用不同平板测定了WG-2和Y106 2个菌株对小麦全蚀病菌的拮抗能力以及产生葡聚糖酶、几丁质酶、壳聚糖酶和蛋白酶等真菌细胞壁降解酶的能力,发现2个菌株间差别明显,暗示不同内生生防菌株对小麦全蚀病可能具有不同的生防机制。

Endophytic bacteria with the potential of biocontrol against wheat take-all caused by Gaeumannornyces graminis var. tritici were studied. A total of 530 wheat endophytic bacteria were isolated from 82 healthy root systems of wheat varieties originated from Henan wheat growth area. In vivo tests were used so as to acquire biocontrol strains controlling take-all of wheat efficiently and the results showed that 15 strains could reduce significantly the incidences and severity of wheat take-all. Control efficla.cy of strain WG-2 and Y106 against take-all of wheat reached 83.25% and 80.37% respectively,which were significantly better than the control effica- cy of triadimefon（77.05 %）, a usually used pesticide against the take-all disease. Methods of mor- phological observation,physiological and biochemical analyses and comparison of bacteria 16S rDNA sequences were used to identify the biocontrol strains of WG-2 and Y106. The results showed that WG-2 and Y106 belonged to Serratia proteamaculans and Bacillus subtilis, respectively. Mixture of WG-2 and Y106 could not improve their control efficacy against take-all of wheat, which indicated that the two strains were incompatible. Antagonistic activity against G. graminis var. tritici and ability to produce fungal cell wall degrading enzymes such as glucanase,chitinase, proteinase,etc,of strains WG-2 and Y106 were tested on different plates. The results indicated that different biocontrol mechanisms existed among different endophytic bacteria.