SeBLOS2 knockout via CRISPR/Cas9 leads to the loss of larval integument coloration in Spodoptera exigua (Lepidoptera: Noctuidae)

Abstract

CRISPR/Cas9 technology is a precise and powerful tool for functionally exploring insect genes. The present study tested CRISPR/Cas9 as a way of undertaking effective gene mutagenesis in an important agricultural pest, the beet armyworm Spodoptera exigua. Based on a S. exigua transcriptome database, the entire complementary DNA sequence of SeBLOS2 encoding 140 amino acid residues was cloned. The gene was highly expressed in late larval stages (L3–L5). Using the CRISPR/Cas9 method, SeBLOS2 was knocked out by altering two sites in the coding region. This resulted in 70%–74% of the G0 generation (L4–L5) larvae displaying mosaic translucent integument. Four different mutations occurred at SeBLOS2‐specific target sites, as demonstrated by further polymerase chain reaction‐based genotypic analysis. Homozygote mutant L3 larvae were obtained in the G1 generation, with complete loss of white stripes and spots on their larval integument. These results demonstrate a crucial role of SeBLOS2 in integument pigmentation and suggest that the gene can act as a suitable nonlethal marker for functional research on genes in S. exigua and other Lepidopteran pests.