Digital Gene Expression Profiling And Symbiosis Related Genes Enriched Pathways Analysis Of Heterorhabditidoides Chongmingensis Associated With Serratia Nematodiphila Strains

Entomopathogenic nematodes(EPNs)are obligate parasitism insect pathogens,which are widely used to control agricultural pests,and serve as a kind of important biological control agents.There are many traits of EPNs includeing the active searching host ability,high efficiency and pathogenicity for killing pests,easily to mass production and being safe to human and environment,and so forth.Heterorhabditidoides chongmingensis DZ0503CMFT(DZ)is a novel member of entomopathogenic nematodes that has evolved a mutualism relationship with Serratia nematodiphila DZ0503SBS1T(S1)bacteria to serve as a highly virulent insect pathogen.Our previous study showed that when associated with non native bacterial strain S.nematodiphila DR186(186),the developmental rate,sex ratio of its first generation adults,bacterial carriage rate and output for its next generation IJs of the monoxenic nematode-bacterium complex DZ/186,were significantly lower than those of the wild combination DZ/S1.In order to deep understanding the impact of different symbiotic bacteria strain on growth;development and reproduction of the nematode,digital gene expression profiling(DGE)sequencing libraries of the monoxenie nematode-bacterium complexes DZ/S1 and DZ/186 were constructed and sequencing.The key methods and main results are as follows:After mapping and statistics analysis of the DGE sequencing reads with reference transcriptome data of Heterorhabditidoides chongmingensis,10,043 differentially expressed genes(DEGs)were identified,1,246 of which showed up-regulated trends and 8,797 of them showed down-regulated trends.Then the DEGs were functional annotated by GO and KEGG pathway significantly enriched analysis.The GO functional classification showed that the DEGs were assigned to 50 sub-GO terms:single-organism process,cellular process,multicellular organism process,development process,metabolic process and in other biological process;cell,organelle,membrane,their components and other cell component;and catalytic activity,binding,transporter activity and other molecular function.KEGG pathway enriched analysis showed that the DEGs were significantly enriched in 23 pathways,such as Tuberculosis,Small cell lung cancer,Focal adhesion,ECM-receptor interaction,Amoebiasis and Basal transcription factors.Five up-regulated genes and five down-regulate genes were selected for quantitative PCR analysis to validate the accuracy of DEG data.QRT-PCR results of these genes showed the same up/down trends as DGE data with significantly positive correlation(correlation coefficient R2= 0.80)between them.These results confirmed the accuracy of DGE data in this study.Quit a few parts of the DEGs were assigned to growth,development and reproduction biological processes,indicating that the growth,development and reproduction processes were inhibited in the recombined monoxenic nematode-bacterium complex DZ/186.Three pathways,ECM-receptor interaction,focal adhesion and regulation of actin cytoskeleton,were involved in regulating reproduction of H.chongmingensis.A considerable part of DEGs were enriched in primary metabolic processes and showed down-regulated trends,which were negatively to the development rate and reproduction of DZ/186,indicating the primary metabolic processes may play an important role in the growth and development of H.chongmingensis.