Silencing of cyp-33C9 Gene Affects the Reproduction and Pathogenicity of the Pine Wood Nematode, Bursaphelenchus xylophilus

Abstract

Cytochrome P450 genes are very important for plant-parasitic nematodes to reproduce and to metabolize xenobiotic compounds generated by their host plants. The pine wood nematode (PWN), <i>Bursaphelenchus xylophilus</i>, causes very high annual economic losses by killing large numbers of pine trees across Asia and into Europe. In this study, we used RNA interference (RNAi) to analyze the function of the <i>cyp-33C9</i> gene of PWN. Our results showed that expression of the <i>cyp-33C9</i> gene was suppressed successfully after soaking nematodes for 24 h in <i>cyp-33C9</i> double-stranded RNA (dsRNA). The silencing of the <i>cyp-33C9</i> gene significantly decreased the feeding, reproduction, oviposition and egg hatch of <i>B. xylophilus</i>. Meanwhile, the migration speed of <i>B. xylophilus</i> in <i>Pinus thunbergii</i> was reduced in the early stages when the <i>cyp-33C9</i> gene was silenced in the nematodes. Moreover, knockdown of the <i>cyp-33C9</i> gene in <i>B. xylophilus</i> caused a decrease in pathogenicity to pine trees. These results suggest that the <i>cyp-33C9</i> gene plays an important role in the reproduction and pathogenicity of <i>B. xylophilus</i>. This discovery identified several functions of the <i>cyp-33C9</i> gene in <i>B. xylophilus</i> and provided useful information for understanding the molecular mechanism behind pine wilt disease caused by PWN.