Identification And Pathogenicity Analysis Of The Pathogen Causing Peanut Pod Rot

In recent years,peanut pod rot has become more and more serious in China.The severe yield reduction and significant economic losses were caused by the disease in major peanut producing areas such as Shandong,Henan and Hebei province.To identify the pathogen causing peanut pod rot in Hebei province and preliminary analysis its pathogenicity,the contents and results are as follows:(1)The dominant pathogen of peanut pod rot was Fusarium neocosmosporiellum(Formerly known as Neocosmospora vasinfecta)by Koch’s postulates.The isolate rates of F.neocosmosporiellum were 74.1%、78.6% and 75.6% from Daming county,Xinle city and Changli county of Hebei province,respectively.The optimal culture temperature of mycelia was 28-30°C,the optimal culture light condition was continuous dark,but the optimum culture medium was different.The optimal temperature for conidia germination was 30°C.The pathogenicity of F.neocosmosporiellum XL-3 was the strongest among 3 strains pathogens.This shows that the biological characteristics and pathogenicity of 3 strains pathogens isolated from different regions are different.(2)The whole genome of F.neocosmosporiellum XL-3 was sequenced by using third-generation DNA sequencing technology.The total length of the genome was60.88 Mb,and GC content was 48.53%.A total of 12596 genes were obtained by genome functional annotation,accounting for 98.75% of the predicted genes,and the number of metabolism-related genes was more than 10%.35 secondary metabolic gene clusters were predicted by Anti SMASH analysis,including 9 terpene gene clusters and 7 PKS.(3)Crude extracts of F.neocosmosporiellum XL-3 were analyzed by HPLC-MS.11 compounds were speculated by ESI-MS mass spectrometry analysis combined with KNAp SAc K Core System and Pub Chem,including 4 terpenoids X1,X2,X4 and X8,3 polyketones X3,X6 and X11,2 alkaloids X9 and X10,1 flavonoids X7 and 1phenolic acids X5.Compounds X2 and X3 have been reported to have phytotoxic activities,which were speculated to play an important role in the pathogenic process.In this study,F.neocosmosporiellum was identified as the pathogen of peanut pod rot in Hebei province.The biological characteristics of mycelium,the whole genome sequence and secondary metabolites were preliminarily analyzed.This study provided a basis for studying the biosynthetic pathway,regulatory mechanism and metabolic network of secondary metabolites in F.neocosmosporiellum.