Gerald Reeck, Raman Chandrasekar, Matthew Aksamit, Doina Caragea, Xiao-Wei Wang, Shu-Sheng Liu, Le Kang, Feng Cui and James Balthazor
The aim of this research project is to compile and analyze numerous sources of transcriptomic and proteomic published works into an initial attempt at a comprehensive salivary transcriptome with considerations into various insect species. Published transcriptomic and proteomic results with RNA-Seq analysis of pea aphid salivary gland RNAs were used to create a comprehensive catalog of pea aphid (Acyrthosiphon pisum) salivary proteins. Duplications of transcripts within the approximately 15 referenced transcriptomics-based papers were eliminated, as were duplications within the approximately 10 referenced proteomics-based papers and duplications between transcriptomic and proteomic work. For studies that had been done in aphids other than the pea aphid, orthologs in the pea aphid were identified by blast searches. The result is a proposed 131-component salivaproteome for the pea aphid, 45 entries of which were identified by proteomics and 102 by transcriptomics, with 16 proteins (and their encoding transcripts) having been identified in both approaches. Transcripts encoding nearly all of the proposed saliva-proteins were verified in pea aphid salivary glands by RNA-Seq analysis. In light of the complexity of the proposed saliva-proteome, we suggest that many different salivas can in fact be produced by a pea aphid by combining different components of the saliva-proteome. Each salivation would be a subset of the total saliva-proteome, customized to meet a particular physiological condition that the species encounters. Thus, the proposed saliva-proteome can provide a basis for systems-level studies of aphid salivations. Finally, we to show orthology into other insect species, it was found that approximately 80 components of the proposed pea aphid saliva-proteome have orthologs in a whitefly, Bemisia tabaci. This suggests that a common core of orthologous proteins and enzymes exists in the salivations of aphids and whiteflies.
