Multigenic Natural Variation Underlies Caenorhabditis elegans Olfactory Preference for the Bacterial Pathogen Serratia marcescens

摘要

The nematode Caenorhabditis elegans can use olfaction to discriminate among different kinds of bacteria, its major food source. We asked how natural genetic variation contributes to choice behavior, focusing on differences in olfactory preference behavior between two wild-type C. elegans strains. The laboratory strain [N2][1] strongly prefers the odor of Serratia marcescens , a soil bacterium that is pathogenic to C. elegans , to the odor of Escherichia coli , a commonly used laboratory food source. The divergent Hawaiian strain [CB4856][2] has a weaker attraction to Serratia than the [N2][1] strain, and this behavioral difference has a complex genetic basis. At least three quantitative trait loci (QTLs) from the [CB4856][2] Hawaii strain (HW) with large effect sizes lead to reduced Serratia preference when introgressed into an [N2][1] genetic background. These loci interact and have epistatic interactions with at least two antagonistic QTLs from HW that increase Serratia preference. The complex genetic architecture of this C. elegans trait is reminiscent of the architecture of mammalian metabolic and behavioral traits. [1]: http://www.wormbase.org/db/get?name=N2;class=Strain [2]: http://www.wormbase.org/db/get?name=CB4856;class=Strain.