Efficient DIPA-CRISPR-mediated knockout of an eye pigment gene in the white-backed planthopper,Sogatella furcifera

Although CRISPR/Cas9 has been widely used in insect gene editing,the need for the microinjection of preblastoderm embryos can preclude the technique being used in insect species with eggs that are small,have hard shells,and/or are difficult to collect and maintain outside of their normal environment.Such is the case with Sogatella furcifera,the white-backed planthopper(WBPH),a significant pest of Oryza sativa(rice)that oviposits inside rice stems.Egg extraction from the stem runs the risk of mechanical damage and hatching is heavily influenced by the micro-environment of the rice stem.To bypass these issues,we targeted embryos prior to oviposition via direct parental(DIPA)-CRISPR,in which Cas9 and single-guide RNAs(sgRNAs)for the WBPH eye pigment gene tryptophan 2,3-dioxygenase were injected into the hemocoel of adult females.Females at varying numbers of days posteclosion were evaluated to determine at what stage their oocyte might be most capable of taking up the gene-editing components.An evaluation of the offspring indicated that the highest G0 gene-edited efficacy(56.7%)occurred in females injected 2 d posteclosion,and that those mutations were heritably transmitted to the G1 generation.This study demonstrates the potential utility of DIPA-CRISPR for future gene-editing studies in non-model insect species and can facilitate the development of novel pest management applications.