An aphid RNA transcript migrates systemically within plants and is a virulence factor

Abstract

Aphids are sap-feeding insects that colonize a broad range of plant species and often cause feeding damage and transmit plant pathogens, including bacteria, viruses, and viroids. These insects feed from the plant vascular tissue, predominantly the phloem. However, it remains largely unknown how aphids, and other sap-feeding insects, establish intimate long-term interactions with plants. To identify aphid virulence factors, we took advantage of the ability of the green peach aphid <i>Myzus persicae</i> to colonize divergent plant species. We found that a <i>M. persicae</i> clone of near-identical females established stable colonies on nine plant species of five representative plant eudicot and monocot families that span the angiosperm phylogeny. Members of the novel aphid gene family <i>Ya</i> are differentially expressed in aphids on the nine plant species and are coregulated and organized as tandem repeats in aphid genomes. Aphids translocate <i>Ya</i> transcripts into plants, and some transcripts migrate to distal leaves within several plant species. RNAi-mediated knockdown of <i>Ya</i> genes reduces <i>M. persicae</i> fecundity, and <i>M. persicae</i> produces more progeny on transgenic plants that heterologously produce one of the systemically migrating <i>Ya</i> transcripts as a long noncoding (lnc) RNA. Taken together, our findings show that beyond a range of pathogens, <i>M. persicae</i> aphids translocate their own transcripts into plants, including a <i>Ya</i> lncRNA that migrates to distal locations within plants, promotes aphid fecundity, and is a member of a previously undescribed host-responsive aphid gene family that operate as virulence factors.