Natural genetic variation in the pheromone production of C. elegans

From bacterial quorum sensing to human language, communication is essential for social interactions. Nematodes produce and sense pheromones to communicate among individuals and respond to environmental changes. These signals are encoded by different types and mixtures of ascarosides, whose modular structures further enhance the diversity of this nematode pheromone language. Interspecific and intraspecific differences in this ascaroside pheromone language have been described previously, but the genetic basis and molecular mechanisms underlying the variation remain largely unknown. Here, we analyzed natural variation in the production of 44 ascarosides across 95 wild Caenorhabditis elegans strains using high-performance liquid chromatography coupled to high-resolution mass spectrometry. We discovered wild strains defective in the production of specific subsets of ascarosides (e.g., the aggregation pheromone icas#9) or short- and medium-chain ascarosides, as well as inversely correlated patterns between the production of two major classes of ascarosides. We investigated genetic variants that are significantly associated with the natural differences in the composition of the pheromone bouquet, including rare genetic variants in key enzymes participating in ascaroside biosynthesis, such as the peroxisomal 3-ketoacyl-CoA thiolase, daf-22, and the carboxylesterase cest-3. Genome-wide association mappings revealed genomic loci harboring common variants that affect ascaroside profiles. Our study yields a valuable dataset for investigating the genetic mechanisms underlying the evolution of chemical communication.