Closing the Gap: Horizontal Transfer of Mariner Transposons between Rhus Gall Aphids and Other Insects

SIMPLE SUMMARY: Transposable elements (TEs) are mobile genetic elements that invade and multiply in host genomes. Besides vertical inheritance, it can transfer from one species to another through a phenomenon called horizontal transfer (HT). HT is crucial for TEs survival in genomes but also a significant disadvantage for host genomes, and recurrent HTT events between different hosts could shape and affect their genome architecture. HTT could be harmful to host genomes, but sometimes it can be useful and may play a role in the adaptive evolution of the host genome. HTT is well reported in many eukaryotes; however, there is still a considerable gap of knowledge about HTT in some organisms. This study closed the knowledge gap about HTT regarding Rhus gall aphids and reported multiple events of HTT involving Rhus gall aphids and other insects. ABSTRACT: Horizontal transfer of transposons (HTT) is an essential source of genomic evolution in eukaryotes. The HTT dynamics are well characterized in eukaryotes, including insects; however, there is a considerable gap in knowledge about HTT regarding many eukaryotes’ species. In this study, we analyzed the events of the HTT between Rhus gall aphids (Hemiptera) and other insects. We analyzed the Mariner-like transposable elements (MLEs) belonging to Rhus gall aphids for the possible HT events. The MLEs have a patchy distribution and high similarity over the entire element length with insect MLEs from different orders. We selected representative sequences from the Rhus gall MLEs and identified five events of HT between MLEs of Rhus gall aphids and other insects from five different orders. We also found multiple HTT events among the MLEs of insects from the five orders, demonstrating that these Mariner elements have been involved in recurrent HT between Rhus gall aphids and other insects. Our current study closed the knowledge gap surrounding HTT and reported the events between Rhus gall aphids and other insects for the first time. We believe that this study about HTT events will help us understand the evolution and spread of transposable elements in the genomes of Rhus gall aphids.