Pathogenicity Of Beauveria Bassiana Against Brontispa Longissima And It's RNA-seq Analysis

Brontispa longissima is an important quarantine pest,After invasiving in 1992,it caused great harm to palm plants.Beauveria bassiana is one kind of insect pathogenic fungus and it is widely used in biological control.The aim of study was screening the high pathogenicity of B.bassiana strains against B.longissima.After it,study the biological characteristics of the highly pathogenic strains.Analysed B.bassiana's differential expression genes in different medium with RNA-seq.For biological control to B.longissima established theoretical basis.Using 6 strains of B.bassiana to test the pathogenicity abut adult and larval of B.longissima.The results showed that the BB strain was the strongest virulence against B.longissima after being inoculated with spore·mm-2 with(1+0.5)×107 spore·mL-1 for 10 days.The corrected mortality of B.longissima adult,1-2 ages larvae,3-4 ages larvae,over 5 ages larvae were(94.67±0.89)%,(84.34±3.33)%,(76.07±1.16)%and(73.68±1.09)%,respectively.and their cadaver rate were(92.80±0.81)%,(83.63±2.64)%,(74.64±2.37)%and(72.33±1.76)%,LT50 were defined 5.33,5.79,6.71,and 6.98 days.The LC50 for 6 days were 9.036×105spore·ml-1,9.005×106spore·ml-1,3.451×107spore·ml-1 and 4.727×107spore·ml-1.The time-dose-mortality model proved that the peak time of death for the B.longissima adult and the larval were for the 2-4 days and 2-6 days respectively.2.Studied on biological characteristics of the BB strain,the results showed that the PPDA medium were the best adapt to conidia production and mycelia growth among five kinds commonly medium.In PPDA medium,the conidia production of BB strain was(11.18±0.10)spore·cm-2.The mycelia growth speed was(4.77±0.039)mm·d-1.The best Carbon and Nitrogen source for BB strain was Glucose and Peptone.The optimum temperature for the spore production and germination of BB strains was 25-28?.And the optimal humidity for BB strain spore germinating was more than 90%.3.Analysed B.bassiana's differential expression genes in different medium with RNA-seq.The results showed that,there were a lot of different expressed RNA genes in different time and medium.By the clustering methodology,there were 55 genes up-regulated in insect medium,they may have a great relationship with the pathogenicity.In the different times of insect medium,the most powerful differential expression genes were Unigene0009540 and Unigene0001816.In NCBI data base the Unigene0009540 note was regulate the activation,decompose the steroids by specific enzymes.So it may have relationship with decompose the steroids in insect cell during the infection process.The Unigene0001816 was one of the key genes in regulation of gene expression,the powerful expression of Unigene0001816 can be speculated that there are a lot of genes up-regulated or down-regulated during the infection process.