Abstract

Methionine aminopeptidases (MetAPs) catalyze the cleavage of the N-terminal initiator methionine (iMet) in new peptide chains and arylamides, which is essential for protein and peptide synthesis. MetAP is differentially expressed in two diamondback moth (DBM;Plutella xylostella) strains: the G88 susceptible strain and the Cry1S1000 strain, which are resistant to the Bt toxin Cry1Ac, implicating that MetAP expression might be associated with Bt resistance. In this study, we identified and cloned a MetAP gene from DBMs, namedPxMetAP1, which has a CDS of 1140 bp and encodes a 379 amino acid protein. The relative expression ofPxMetAP1was found to be ~2.2-fold lower in the Cry1S1000 strain compared to that in the G88 strain.PxMetAP1presents a stage- and tissue-specific expression pattern, with higher levels in the eggs, adults, integument, and fatbody of DBMs. The linkage betweenPxMetAP1and Cry1Ac resistance is verified by genetic linkage analysis. The knockout ofPxMetAP1in G88 by CRISPR/Cas9 leads to a ~5.6-fold decrease in sensitivity to the Cry1Ac toxin, further supporting the association between thePxMetAP1gene and Bt tolerance. Our research sheds light on the role of MetAP genes in the development of Bt tolerance inP. xylostellaand enriches the knowledge for the management of such a cosmopolitan pest.Keywords:Plutella xylostella;methionine aminopeptidase;Bt tolerance;genetic linkage;CRISPR/Cas9