Phenotypic Characterization And Transcriptome Analysis Of Bursaphelenchus Xylophilus Treated With Different Temperatures

Pine wilt disease is a devastating disease of pine trees,which is also called the pine wilt disease.Its pathogen is Bursaphelenchus xylophilus to be internationally recognized as important forestry biological quarantine object.Since found in Nanjing in 1982,the disease spread rapidly,it caused serious economical and ecological disease in China.Bursaphelenchus xylophilus is an invasive species.The temperature affects its ecological expansion,which is an important component of ecological environment.Starting from the environmental temperature factor,the research on the ecological adaptability and mechanisms of Bursaphelenchus xylophilus to environment stress factor is necessary,which is worthy to discuss how it is suitable for the new environment and how to survive and breed.In this paper,we were conducted a series of studies on the ecological factors to response to temperature about Bursaphelenchus xylophilus:We were studied the somatotype and female-male ratio of Bursaphelenchus xylophilus under temperatures acclimation.The Bursaphelenchus xylophilus was under temperature acclimation at 15? and 25?.We got the stable genetic nematode isolates.The body length of Bursaphelenchus xylophilus was 15? higher than that of 25? after acclimation,and the female-male were less than 25 ?.Bursaphelenchus xylophilus was domesticated at 15?,and then placed at 25 ?,30 ? and then continued to culture,in order to obtain the tem perature change on the domesticated it's the body length and the femalemale.Bursaphelenchus xylophilus was cultured at 15? and then switched to culture at 25? and 30?.The 1th and 2th generation of Bursaphelenchus xylophilus body length decreased significantly.With the prolongation of culture time,it's 4th and 5th generation gradually stabilized.We explored the sex determination critical period,and preliminary determined it was in embryo incubation stage.Response of Bursaphelenchus xylophilus to low temperature stress under two temperature acclimation.At low temperature of-20?,the hatching rate of cultured Bursaphelenchus xylophilus decreased with the prolonging of treatment time.In a certain period of time,the hatching rate of Bursaphelenchus xylophilus eggs at 15? was higher than that of eggs under 25?acclimation.Within a certain period of time,Bursaphelenchus xylophilus at-20?centigrade environment,it's survival rate at 15? was higher than that under 25?.Different thawing methods have a certain influence on the damage rate of Bursaphelenchus xylophilus.The early thawing stage at 4? is favorable for the survival of Bursaphelenchus xylophilus.Thawing damage rate of Bursaphelenchus xylophilus is under acclimation at 15? below 25?.For a specified period of time,the resistance of Bursaphelenchus xylophilus is under low temperature at 15? was stronger than that at 25?.Transcriptome analysis of Bursaphelenchus xylophilus under acclimation at 15? and 25 ? was conducted.The expression of related genes was up-regulated by glycolysis and gluconeogenesis.It provides intermediate products for the synthesis of secondary metabolites.Significant enrichment of glycolysis,pentose phosphate pathway,fat breakdown and synthesis,they provides an energy source for accumulation of secondary metabolites.KEGG enrichment analysis of differentially expressed genes in transcriptome,We found that Bursaphelenchus xylophilus was acclimated at 15?,whose unc-68 gene,protein cbp-1 gene,HSP70 gene,p68 gene up-regulated expression.They regulate the growth and development,cell proliferation,tolerance,and development of the reproductive organs of Bursaphelenchus xylophilus.The pathway of glycolysis,the organic synthesis pathway of fatty acids,and the calcium signaling pathway are enriched.There was a correlation between the phenotypic difference of Bursaphelenchus xylophilus at 15? and 25?.