In order to define the pathogen of peanut scorch spot disease in Liaoning Province,tissue isolation method was utilized.Its pathogenicity was determined according to Koch's postulates.Morphology of colony,peri-thecia,asci and ascospores was observed.LSU,ITS and Tub2 genes of pathogen were sequenced for multi-gene joint construction analysis.Results showed that the pathogen formed flat colonies with sparse aerial mycelium and smooth and lobate margins.Mycelium was initially white and then changed to black brown from the center of the col-ony.Ascospores were ellipsoid to oblong with a gelatinous sheath and septum.Based on the combined phylogenetic analysis of LSU,ITS and Tub2 gene sequences,the pathogen was identified to be Leptosphaerulina arachidicola causing peanut scorch spot in Liaoning Province.Biological characteristics showed that a suitable temperature for pathogen mycelial growth was 25℃,at the optimal pH 5,under the optimal carbon source of soluble starch,and the optimal nitrogen source of pancreatic peptone.Its lethal temperature of the mycelial was 50℃.
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