Gene silencing targeting uk1_LRR or clathrin in the experimental vector Euscelidius variegatus modifies insect...

The "flavescence dorée" (FD) phytoplasma is transmitted from grapevine to grapevine by the leafhopper Scaphoideus titanus. In experimental conditions, this phytoplasma is also transmitted by the leafhopper Euscelidius variegatus to broad bean in which it multiplies and induces symptoms. To be transmitted to plants, phytoplasmas must invade different cell types of their insect vectors. The process of cellular endocytosis involves both bacterial and eucaryotic factors such as adhesins and receptors. In the present study, it is shown that entry of fluorescent beads coated with the adhesin VmpA of the FD phytoplasma into cultured E. variegatus cells depends on the putative receptor Uk1_LRR and clathrin of the insect. In vivo experiments have shown that silencing of uk1_LRR gene increased the colonization of E. variegatus by the FD phytoplasmas without effect on the plant transmission. On the contrary, silencing of clathrin gene significantly reduced the colonization of E. variegatus and the transmission to broad bean.