부산대학교 도서관

Intracellular symbionts in insects often have reduced genomes. Host acquisition of genes from bacteria is an important adaptation that supports symbionts. However, the function of horizontally transferred genes in insect symbiosis remains largely unclear. The primary symbiont Portierahoused in bacteriocytes lacks pantothenate synthesis genes: panBand panC, which is presumably complemented by a fused gene panB-panC(hereafter panBC) horizontally transferred from bacteria in Bemisia tabaciMEAM1. We found panBCin many laboratory cultures, and species of B. tabacishares a common evolutionary origin. We demonstrated that complementation with whitefly panBCrescued E. colipantothenate gene knockout mutants. Portieraelimination decreased the pantothenate level and PanBC abundance in bacteriocytes, and reduced whitefly survival and fecundity. Silencing PanBCdecreased the Portieratiter, reduced the pantothenate level, and decreased whitefly survival and fecundity. Supplementation with pantothenate restored the symbiont titer, PanBC level, and fitness of RNAi whiteflies. These data suggest that pantothenate synthesis requires cooperation and coordination of whitefly PanBC expression and Portiera. This host–symbiont co-regulation was mediated by the pantothenate level. Our findings demonstrated that pantothenate production, by the cooperation of a horizontally acquired, fused bacteria gene and Portiera, facilitates the coordination of whitefly and symbiont fitness. Thus, this study extends our understanding on the basis of complex host–symbiont interactions.