Akirin regulates the cell development and symbiont abundance of bacteriocytes in embryos of whitefly Bemisia tabaci

Insects have specialized host cells, namely bacteriocytes, to house intracellular symbionts.However, knowledge of the mechanisms underlying regulation of bacteriocyte development and associated symbiont abundance during insect embryogenesis is scarce.One bacteriocyte translocates and divides into two cells, and abundance of bacteriocyte symbionts fluctuates periodically during embryogenesis of whitefly Bemisia tabaci MEAM1.We find that the Akirin gene is highly expressed in bacteriocytes, and its expression level is inversely correlated to symbiont titers during whitefly embryogenesis.Silencing Akirin inhibits the translocation and division of the bacteriocyte in embryos but increases bacteriocyte size and symbiont titers.Akirin controls titers of bacteriocyte symbionts by positively affecting the expression of the antimicrobial peptide gene defensin.Thus, Akirin has a dual function in regulating cell development and symbiont abundance of bacteriocytes in whitefly embryos.This study opens another direction to study mechanisms underlying development regulation of novel cells like bacteriocytes.