Baking piRNAs: Characterization of piRNA expression profiles between virulent and avirulent Aphis glycines

Insects, such as aphids, use many different mechanisms to acquire adaptive traits and overcome host plant resistance (HPR). While common methods include physiological detoxification or evolutionary gene-for-gene models, there is evidence to suggest epigenetic mechanisms play a role as well. Soybean aphids utilize epigenetics commonly during their life history and provide a good model to uncover it’s link to overcoming HPR genes. One epigenetic pathway involves PIWI proteins, which bind to a class of small non-coding RNAs called piRNAs (PIWI-interacting RNAs) to perform a wide range of adaptive functions. Few studies have investigated the role of these epigenetic mechanisms in insect-plant interactions. Here, we aim to characterize piRNA expression in Aphis glycines, a major pest of soybeans, to investigate whether piRNAs contribute to overcoming plant defense mechanisms. Libraries (n=16) were prepared using whole body aphids of two biotypes (adapted and non-adapted) fed two types of soybean (aphid-resistant and aphid-susceptible). Samples were enriched for small RNAs (sRNAs) and sequenced via Illumina Hi-seq. A new bioinformatic pipeline was developed to identify piRNA clusters in the soybean aphid, which can be used to evaluate differences in piRNA expression. We expect to see differential expression profiles of piRNAs similar to findings in other aphid species. This process provides further insight into the role that piRNAs play in plant-insect interactions, potentially contributing to aphid adaptation to host plant resistance. By understanding the cause of these adaptations, we can develop better preventative measures and protect the longevity of HPR as a management tool.