Functional characteristics of Dicer genes in Plutella xylostella

Abstract

BACKGROUNDDicer is an endonuclease that belongs to the RNase III family and can specifically recognize and cleave double‐stranded RNA (dsRNA). In most insects, there are two Dicer genes, Dicer‐1 (Dcr‐1) and Dicer‐2 (Dcr‐2), which are involved in the micro‐RNA and small‐interfering RNA pathways in many species, respectively. The function of Dicer in Plutella xylostella remains unknown.RESULTSThe full‐length open reading frames of P. xylostella Dicer‐1 (PxDcr‐1) and Dicer‐2 (PxDcr‐2) were cloned and sequenced. Dcr‐1 and Dcr‐2 proteins shared similar structural domains with the Dicer‐Partner Binding Domain (Dicer‐PBD) and the double‐strand RNA binding domain (dsRBD) present only in Dcr‐1. The phylogenetic trees showed that lepidopteran Dcr‐1s or Dcr‐2s clustered in one branch, with PxDcr‐1 in the basal position and PxDcr‐2 closest to Plodia interpunctella Dicer. Two homozygous knockout lines, ΔPxDcr‐1 and ΔPxDcr‐2, were obtained by using the CRISPR–Cas9 technique. The ΔPxDcr‐1 strain exhibited a high mortality rate, a low eclosion rate, a low egg‐laying rate, a low hatching rate, and a shriveled ovariole without mature eggs. The ΔPxDcr‐2 strain showed no significant difference from the wild‐type in terms of survival, development and reproduction, but the RNA interference (RNAi) efficiency caused by dsRNA was significantly reduced.CONCLUSIONThese findings demonstrate the involvement of PxDcr‐1 in the development and reproduction of P. xylostella, specifically in the formation of ovarioles and eggs, and PxDcr‐2 is indispensable for RNAi. These findings shed light on the function of Dcr‐1 and Dcr‐2 in Lepidoptera. © 2023 Society of Chemical Industry.