Abstract
Pieris butterflies recognize host Brassicaceae plants via sensing glucosinolates, but the molecular mechanism remains unclear. Here, we cloned five gustatory receptor genes highly expressed in larval mouthparts, adult foreleg tarsi, and the proboscis of Pieris rapae and then ectopically expressed each of them in Gr5a neurons of Drosophila and determined responses of the neurons to glucosinolates. Among them, only Gr5a > PrapGr19 neurons respond to gluconapin dose-dependently. Knockdown of PrapGr19 by 52.3% significantly reduces the firing rate of the lateral sensilla styloconica in the fifth instar larvae of P. rapae to gluconapin but has no effect on the responses to sinigrin and sucrose. This leads to the loss of the feeding preference of larvae for gluconapin and Cleome spinosa. All these results indicate PrapGr19 is the receptor mediating P. rapae larvae sensing gluconapin, which provides new knowledge for revealing molecular bases of glucosinolate sensing in Pieris butterflies.
