Modulation of yellow expression contributes to thermal plasticity of female abdominal pigmentation in Drosophila melanogaster

Phenotypic plasticity describes the ability of a given genotype to produce distinct phenotypes in different environments. We use the temperature sensitivity of abdominal pigmentation in Drosophila melanogaster females as a model to analyse the effect of the environment on development. We reported previously that thermal plasticity of abdominal pigmentation in females involves the pigmentation gene tan (t). However, the expression of the pigmentation gene yellow (y) was also modulated by temperature in the abdominal epidermis of pharate females. We investigate here the contribution of y to female abdominal pigmentation plasticity. First, we show that y is required for the production of black Dopamine-melanin. Then, using in situ hybridization, we show that the expression of y is strongly modulated by temperature in the abdominal epidermis of pharate females but not in bristles. Interestingly, these two expression patterns are known to be controlled by distinct enhancers. However, the activity of the y-wing-body epidermal enhancer only partially mediates the effect of temperature suggesting that additional regulatory sequences are involved. In addition, we show that y and t co-expression is needed to induce strong black pigmentation indicating that y contributes to female abdominal pigmentation plasticity.