Whole-Genome Resequencing−Based Qualitative Trait Locus Mapping Correlated yellow with the Mutant Color in Honeybees, Apis cerana cerana

This study examined the genetic basis of a mutation in cuticle color in the honeybee Apis cerana cerana using genome resequencing of wild−type and mutant drones produced by a single virgin queen. A candidate locus was identified by calculating the Euclidean distance between mutants and wild types at each SNP, performing Lowess regression to fit a curve to these data, and setting a threshold of the top 0.5% Euclidean distance for candidate region selection. From this, genes with synonymous substitutions became candidate genes. One of these genes, the yellow gene, had a 2 bp deletion causing a frameshift mutation. RT−qPCR of this gene was performed on RNA extracted from mutant and wild−type drones; gene expression was only significantly different between wild types and mutants at the yellow gene. Finally, RNA interference silencing of the yellow gene was used to reduce yellow gene expression in workers and putatively result in a lighter coloration. These results indicate that the yellow gene participated in the body pigmentation, and its defect was responsible for the brown mutation. It promotes the understanding of the molecular basis of body coloration in honeybees, enriching the molecular mechanisms underlying insect pigmentation.