Meeting Abstract
The aphid/Buchnera symbiosis was the first insect nutritional endosymbiosis for which the genome of both the insect and its symbiont were known. In this model, Buchnera are housed intracellularly in bacteriocytes within bacteriomes where they work to provide essential amino acids to the host aphid. Recently, we worked to characterize miRNAs that are implicated in regulation of the symbiosis in the green peach aphid, Myzus persicae. To do this we generated small RNA-seq datasets from aphid gut and bacteriome tissue. Remarkably, we found that 45% of reads in gut samples failed to map to the aphid and/or Buchnera genomes. In contrast, only 5% of reads from bacteriome samples failed to map to the aphid and/or Buchnera genomes. Here we report our interrogation of the 45% of small RNA-seq reads in gut samples that failed to map to the insect and/or symbiont genome. We found that viruses and possible secondary symbionts were not likely sources of these reads. Rather, 67% of these unknown reads mapped to the genome of the host plant, Brassica oleracea. B. oleracea reads represented 31% of all reads from gut tissue samples. A subset of these B. oleracea-mapped small RNAs were annotated as plant miRNAs with putative targets in the both the B. oleracea and M. persicae genomes. Our results provide foundational evidence for the regulation of aphid gene expression by plant-encoded miRNAs. This knowledge both advances understanding of cross-kingdom gene regulation in plants and insects, and expands understanding of the regulatory interactions surrounding aphid feeding.
