Resilin is needed for wing posture in Drosophila suzukii.

Resilin is a protein matrix in movable regions of the cuticle conferring resistance to fatigue. The main component of Resilin is Pro-Rresilin that polymerises via covalent di- and tri-tyrosine bounds (DT). Loss of Pro-Resilin is nonlethal and causes a held-down wing phenotype (hdw) in the fruit fly Drosophila melanogaster. To test whether this mild phenotype is recurrent in other insect species, we analysed resilin in the spotted-wing fruit fly Drosophila suzukii. As quantified by DT autofluorescence by microscopy, DT intensities in the trochanter and the wing hinge are higher in D. suzukii than in D. melanogaster, while in the proboscis the DT signal is stronger in D. melanogaster compared to D. suzukii. To study the function of Pro-Resilin in D. suzukii, we generated a mutation in the proresilin gene applying the Crispr/Cas9 technique. D. suzukii pro-resilin mutant flies are flight-less and show a hdw phenotype resembling respective D. melanogaster mutants. DT signal intensity at the wing hinge is reduced but not eliminated in D. suzukii hdw flies. Either residual Pro-Resilin accounts for the remaining DT signal or, as proposed for the hdw phenotype in D. melanogaster, other DT forming proteins might be present in Resilin matrices. Interestingly, DT signal intensity reduction rates in D. suzukii and D. melanogaster are somehow different. Taken together, in general, the function of Pro-Resilin seems to be conserved in the Drosophila genus; small differences in DT quantity, however, allow us to hypothesise that Resilin matrices might be modulated during evolution probably to accommodate the species-specific lifestyle.