Screening Of Antagonistic Endophytic Bacteria In Oilseed Rape And Their Inhibitory Effects Against Sclerotinia Sclerotiorum

Rape stem rot caused by Sclerotinia sclerotiorum is a worldwide disease and bring serious damage to China’s oilseed rape production. In recent years, with environmental pollution, ecological damage and safety of agricultural products and other issues becoming increasingly prominent, traditional chemical control is no longer applicable. Using biocontrol agents to prevent and control the disease has become a hot research. The application of endophyte is more prominent in this regard. We screened the bacteria from oilseed rape to prevent and control the occurrence of rape Sclerotinia rape stem rot. The main results are as follows:1Two biocontrol strains were isolated from the oilseed rape. In them, strain SF4was found to have the best control efficacy. Continuous passage culture showed that it has-genetic stability and in the dual-culture test in plates, their inhibitory rates against S. sclerotiorum were54.12%and63.53%. Strain SF4inhibited the growth of mycelia and induced alterations on mycelium morphology of S. sclerotiorum, such as mycelium inclusions uneven distributed, twist and fracture. The volatile products and cell-free fermentation broth of SF4could both inhibit the growth of mycelia.2Antibacterial activity of cell-free fermentation broth from endophytic bacteria SF3and SF4were tested. The results showed that:cell-free fermentation broth from the two strains both could inhibit S. sclerotiorum. Cell-free fermentation broth from SF3cultured72hour had the best inhibitory effect, when the SF4cultured96hour. The inhibitory activity of cell-free fermentation broth from SF4reduced with the reduction of concentration.3Studied on the effect of SF3and SF4to the growth of S. sclerotiorum.sclerotia. Strain SF3and SF4could both put off sclerotia generation and reduced the number of sclerotia and inhibit the germination of sclerotia of5. sclerotiorum.4The inhibitory activity of volatile products from SF3and SF4against S.sclerotiorum was tested. The results showed that strain SF3and SF4could both inhibit the growth of mycelia. The inhibitory rates were28.66%and33.13%after treated2days.5Analysised the endophytic bacteria SF4against S. sclerotiorum in vitro control effect. The results showed that:The inhibitory rate of bacterial suspension and cell-free fermentation broth of SF4against S. sclerotiorum were100.00%and73.23%respectively.6Tested the antibacterial spectrum of SF4. The results showed that:strain SF4could inhibit a variety of pathogenic fungi. It played a broad antagonistic role in biological control.7The morphological features and physiological and biochemical measurements and16S rDNA sequence analysis of SF4were tested. The results showed that the strain SF4was Bacillus polymyxa.