The effect of anthocyanins intake on the evolution of redox genes: a comparative genomics approach using Drosophila

Anthocyanins are red/blue vacuolar pigments present in flowers and fruits. They belong to flavonoids, a class of well-studied anti-oxidant agents involved with cancer and ageing protection in animals. It has been shown that anthocyanins can regulate the expression of many genes involved with cell redox biology. Little is known about the evolution of these redox genes in species characterized by different anti-oxidant rich diet. An interesting model to study the adaptive effect of anti-oxidant intake on redox genes is Drosophila suzukii: differently from most other Drosophilidae, this species lays eggs in ripening berries which are naturally rich in anthocyanins. We hypothesize that D. suzukii peculiar diet may have resulted in adaptive genetic differences in redox genes. We used a phylogenomics approach to study if a panel of 31 redox related genes are structurally different and/or differently expressed in D. suzukii and D. subpulchrella (another species characterized by fresh fruit diet) compared to other eight species of Drosophila (D. takahashi, , D. biarmipes, D. melanogaster D. simulans, D. erecta, D. yakuba, D. ananassae and D. pseudoobscura). In particular, we studied genes known to be influenced by anti-oxydants, and genes encoding for proteins involved in the reactive oxygen metabolism. Annotations and gene phylogenies indicate that while the coding sequences of all 31 genes are well conserved in all species, some gene is characterized by differences in introns length and/or intron number in D. suzukii. We further inspected the level of selection pressure using dN/dS and we identified genes which have a different rate or sign of positive selection in D. suzukii. We are performing comparative transcriptomic experiments to quantify if these, and other genes, are differently expressed in D. suzukii (and D. subpulchrella) and we will test gene expression in larvae stadium of D. suzukii and other species in different anthocyanins concentrations.