Wolbachiais a nutritional symbiont inDrosophila melanogaster

Abstract

ABSTRACTThe intracellular bacteriumWolbachiais a common symbiont of many arthropods and nematodes, well studied for its impacts on host reproductive biology. However, its broad success as a vertically transmitted infection cannot be attributed to manipulations of host reproduction alone. Using theDrosophila melanogastermodel and their natively associatedWolbachiastrain “wMel”, we show thatWolbachiainfection supports fly development and buffers against nutritional stress.Wolbachiainfection across several fly genotypes and a range of nutrient conditions resulted in reduced pupal mortality, increased adult emergence, and larger size. We determined that the exogenous supplementation of pyrimidines rescued these phenotypes in theWolbachia-free, flies suggesting thatWolbachiaplays a role in providing this metabolite that is normally limiting for fly growth. Additionally,Wolbachiawas sensitive to host pyrimidine metabolism:Wolbachiatiters increased upon transgenic knockdown of theDrosophila de novopyrimidine synthesis pathway but not knockdown of thede novopurine synthesis pathway. We propose thatWolbachiaacts as a nutritional symbiont to supplement fly development and enhance host fitness.SIGNIFICANCE STATEMENTWolbachiais a bacterial symbiont of arthropods and nematodes, well described for its manipulations of arthropod reproduction. However, many have theorized there must be more to this symbiosis, even in well-studiedWolbachia-host relationships such withDrosophila. Reproductive impacts alone cannot explain the success and ubiquity of this bacterium. Here, we useDrosophila melanogasterand their nativeWolbachiainfections to show thatWolbachiasupports fly development and significantly buffers flies against nutritional stress. Additionally, we show that this advantage is likely mediated by pyrimidines. These developmental advantages might help explain the ubiquity ofWolbachiainfections.