Control Of Rice Sheath Blight By Bacillus Cereus With Jinggangmycin Aqua

Two strains of Bacillus cereus WR and XC were isolated from Wenkuqing and Sikanglian respectively.Five resistant strains of Bacillus cereus were obtained by mutagenesis of NTG and further domestication of jinggangmycin aqua.Through naturalization of shake flask and flat plate,a strain of Bacillus cereus designated WR-12 was obtained,which had about five times higher resistance to jinggangmycin aqua than that of the original strain WR-1.The strain Bacillus cereus WR-12 had synergistic inhibition to Rhizoctonia solani with jinggangmycin aqua on double-deck flat plate with the detection of filter paper method.After the study of the main fermental condition of WR-12,the results showed that its spore yield and its resistance to jingangmycin aqua both got to the higher value when fermental time was 60 h and incipient pH was 6.0.The strain WR-12 had higher spore yield and resistance when the fermentation medium was composed of amidulin 10.0 g/L,peptone 12.0 g/L,KH2P04 0.1 g/L,CaCO30.3 g/L.In order to study the mechanism of synergistic inhibition of Bacillus cereus with jinggangmycin aqua to rice sheath blight and provide a basis for its application in production.The effect of Bacillus cereus and jinggangmycin aqua on PAL,CAT and SOD in rice leaves were studied.The activities of PAL,CAT and SOD in rice leaves were significantly increased after spraying Bacillus cereus and/or jinggangmycin aqua.Taking the rice with rice sheath blight as the control.The activities of PAL,CAT and SOD were respectively increased by 56.0%,152.1%;100.06%,148.27%;94.74%,181.15%in comparison with untreated disease rice after 7 d and 20 d in 2009;The activities of the three enzyme respectively increased by 67.80%,27.50%;71.89%,69.11%;112.50%,33.45%in comparison with untreated disease rice after 7 d and 15 d in 2010.Bacillus cereus and jinggangmycin aqua not only had strong antimicrobial effect,but also might enhance disease resistance in order to prevent pathogen infection.The susceptibility rate of rice dropped by 46.5%,the disease index decreased by 55.0%,and the rice yeild increased by 16.98%in 2009.The susceptibility rate of rice dropped by 12.91%,the disease index decreased by 13.00%,and the rice yeild increased by 8.18%in 2010.Bacillus cereus mixed with jinggangmycin aqua as a new pesticide could induce rice disease resistance to sheath blight.