Using a combination of CRISPR/Cas9, behavioural experiments and functional analysis to characterise taste receptors in honeybees

Honeybees (Apis mellifera) need their fine sense of taste to evaluate nectar and pollen sources. Gustatory receptors (Grs) translate taste signals into electrical (ionotropic) responses. In vivo experiments primarily demonstrate collective responses of the whole Gr-set, but little is known about the individual impact of receptors. Here, we disentangle for the first time the contributions of three gustatory receptors (AmGr1, AmGr2, AmGr3) in sugar sensing of honeybees by combining CRISPR/Cas9 mediated genetic knock-out, electrophysiology and behavior. AmGr1 responds to multiple sugars. Bees lacking this receptor have a reduced response to sucrose and glucose but not to fructose. AmGr2 acts as co-receptor of AmGr1 in a heterologous expression system, but honeybee knock-out mutants perform normally. Eliminating AmGr3 while preserving AmGr1 and AmGr2 abolishes the perception of fructose but not of sucrose. We thus dissociate the roles of AmGr1, AmGr2 and AmGR3 in honeybee taste perception.