Biocontrol Effect Of Bacillus Amyloliquefaciens 41B-1 On Sclerotium Tolfsii

Peanut(Arachis hypogaea L.)was one of the most important oil crops with important economic value and nutritional value,but peanut production was seriously influenced by diseases and insect pests,Sclerotium rolfsii was one of the main diseases of peanut.Few study on the growth conditions,inoculation methods and pathogenic conditions of Sclerotium rolfsii was reported.This research was aimed at finding the appropriate culture,inoculation conditions and preventive methods to provide the identification basis of disease and prevent the occurrence of Sclerotium rolfsii.1.The main research results are as followsThe Sclerotium rolfsii was inoculated on the culture medium of different pH values,carbon and nitrogen sources,and treated with different temperature.The pathogen was inoculated on the base of peanut plant,and the temperature and humidity were recorded.The results showed that the optimum pH was 5.0,the optimum growth temperature was 30?.Different carbon and nitrogen sources have different effects.When fructose was used as carbon source and ammonium dihydric phosphate(NH4H2PO4)as the nitrogen source,the mycelium spread fastest.In the temperature of 26??32?,and relative humidity above 90%,inoculation techniques for the experiments were inoculated sclerotia,mycelia plugs,toothpick inoculation and wheat grains inoculated,disease rating was 89%at 15th day after wheat grains inoculated,so it was an effective method.2.The biological control of Bacillus amyloliquefaciens 41B-1 for Sclerotium rolfsiiTo determine the effect of Bacillus amyloliquefaciens 41B-1in suppression of stem rot disease of groundnut plants caused by Sclerotium rolfsii.The inhibitory effect of 41B-1 on hyphal growth was detected after coculture 41B-1 strain with Sclerotium rolfsii on PDA.Under greenhouse conditions,we observed the resistant ability of groundnut plants treated with 41B-1 after a challenging inoculation with Sclerotium rolfsii.The results showed that strain 41B-1 significantly inhibited hyphal growth,destroyed hyphal structure and reduced the number of sclerotia.The results also showed that the 41B-1 strain had good colonization ability in the roots of plants,in addition,the colonization of Sclerotium rolfsii in the roots of plants was reduced and disease index was significantly lower than that in the control.41B-1 strain exhibited greater than 90%biocontrol efficacy against Sclerotium rolfsii in groundnut plants under greenhouse conditions.3.Analysis of lipopeptide synthesis related genes in 41B-1we compared the gene sequences with Genbank database,and analyzed the amino acid sequence.The results showed that 41B-1 contained iturin synthesis essential genes,as well as,it contained surfactin and fengycin.The discovery and analysis of lipopeptide synthesis related genes had an important role for antibacterial mechanism of 41B-1.This study provided a rapid identification method of peanut resistance varieties for Sclerotium rolfsii based on the research of growth conditions and inoculation method,as well,the 41B-1 strain could be used as biocontrol agent against Sclerotium rolfsii.