Comparison of the assembled grain aphid unigenes with pea aphid mRNA sequences. Among the 32,277 unigenes assembled, 26,667 grain aphid unigenes (yellow) were homologous to pea aphid mRNA sequences, of these, 15,444 were one-to-one orthologs (green), 2,170 were tree-matched orthologs (purple), and 9,053 were homologous to pea aphid mRNA sequences with the ratio of matched region below 50% and some paralogs (light blue). The number of unigenes which were unique to grain aphids compared with pea aphid mRNA was 4,857 (blue). And the remaining 753 sequences (red) which were shorter than 250 bp and had no homologous sequences with pea aphid mRNA identified by BLASTn tool were excluded because they were too short sequence for tBLASTx searching. All orthologs were identified using ETE pipeline with SOS of 0.0.