Characterization of a myrosinase cDNA from Brassica parachinensis and its defense role against Plutella xylostella after suppression

Abstract In Brassicaceae, myrosinase catalyzes the hydrolysis of glucosinolate and plays an important role in anti-herbivore defense. We have cloned and characterized the full- length complementary DNA of myrosinase gene from Brassicaparachinensis that exhibits high sequence identity with myrosinase genes from other Brassica species. To investigate the role of this myrosinase in defense against the diamondback moth （Plutella xylostella）, we constructed an RNA-interference （RNAi） cassette expressing a double-stranded RNA that targeted myrosinase and transfected it into B. parachinensis. Myrosinase was sup- pressed in the resulting transgenic plants. Diamondback moth larvae feeding on transgenic plants had lower larval and pupal weights, longer pupal duration, and lower fecundity than those feeding on non-transgenic plants, suggesting that the diamondback moth has adapted to the glucosinolate-myrosinase defensive system. Therefore, the suppression of myrosinase is a potential approach for controlling the diamondback moth.