Comparative Analysis of Transcriptomes from Secondary Reproductives of Three Reticulitermes Termite Species.

Termites are eusocial insects related to cockroaches that feed on lignocellulose. These insects are key species in ecosystems since they recycle a large amount of nutrients but also are pests, exerting major economic impacts. Knowledge on the molecular pathways underlying reproduction, caste differentiation or lignocellulose digestion would largely benefit from additional transcriptomic data. This study focused on transcriptomes of secondary reproductive females (nymphoid neotenics). Thirteen transcriptomes were used: 10 of Reticulitermes flavipes and R. grassei sequenced from a previous study, and two transcriptomes of R. lucifugus sequenced for the present study. After transcriptome assembly and read mapping, we examined interspecific variations of genes expressed by termites or gut microorganisms. A total of 18,323 orthologous gene clusters were detected. Functional annotation and taxonomic assignment were performed on a total of 41,287 predicted contigs in the three termite species. Between the termite species studied, functional categories of genes were comparable. Gene ontology (GO) terms analysis allowed the discovery of 9 cellulases and a total of 79 contigs potentially involved in 11 enzymatic activities used in wood metabolism. Altogether, results of this study illustrate the strong potential for the use of comparative interspecific transcriptomes, representing a complete resource for future studies including differentially expressed genes between castes or SNP analysis for population genetics.