Control Effect And Mechanism Of Bacillus Amyloliquefaciens On Wheat Take-all

Take-all of wheat, caused by the fungus Gaeumannomyces graminis (Sacc.) Von Arx&Oliver var. tritici Walker (Ggt), is soil born disease, one of the most important root diseasesof wheat worldwide. Nowadays, scholars pay more attention on biocontrol methods forcontrol of this pathogen, because absence of resisitant varieties and effective chemicals, aswell as the limitation of crop rotation in large wheat areas. However, this biocontrol agentsare still not used in practice, therefore it is necessary to screen some biocontrol bacteriumagainst take-all disease of wheat which are insensitive to environment and could adapt tomass production.Based on Bacillus amyloliquefacies Ba-168strain which was screened by our lab fromprimeval forest soil in Qinling Mountains, China, we took a series of researches to knowcontrol effect and mechanism of Bacillus amyloliquefacies on wheat take-all. Table standoffmethod is used to test antibacterial effect of Bacillus amyloliquefacies on Ggt. The resultshowed that Ba-168strain had strong antifungal activity. Then researching the antibacterialrate by mycelial growth rate method, we found that the Ba-168significantly inhibitedmycelial growth of disease pathogens, and the inhibition rate of Ba-168fermentation broth,sterile filtrate and crude extract reached91.9%,91.1%,89.3%, respectively. The antifungalmechanism experiments showed that Ba-168strain leaded to morphological changes ofpathogenic bacterium (Ggt) by enlarged hypha, teratogenic shape, vesicles,distortion or emptycells devoid of cytoplasm in the mycelium.Greenhouse experiment shown that control efficiency of Ba-168fermentation broth,sterile filtrate and crude extract by soaking seeds treatment were excellent (up to70.04%better8.64%than fungicide control) and were higher than after drenching soil treatment. Byobserving the growth condition of wheat seedlings, the results showed that although Ba-168fermentation broth, sterile filtrate, crude extract and fungicide control (12.5%silhtiopham)have promoting effect on seedling growth to a certain extent, the promoting effect of threeBa-168agents treatments were more obvious.Besides, some study had been carried out on the characteristics of Ba-168sterile filtrate.We found that the active metabolite of sterile fermentation of Ba-168had good stability against heat, strong resistance against light (UV and solar light), strong adaptability toacid-base environment, long storage period and security. Moreover, Ba-168strain just need ashort time to produce the active metabolite. In addition, we found that Ba-168can colonize onroot and has a good ability of colonization...