Implication for DNA methylation involved in the host transfer of diamondback moth, Plutella xylostella (L.)

DNA methylation exerts extensive impacts on gene expression of various living organisms exposed to environmental variation. However, little is known whether DNA methylation is involved in the host transfer of diamondback moth, Plutella xylostella (L.), a worldwide destructive pest of crucifers. In this study, we found that P. xylostella genome exhibited a relatively low level of DNA methylation on the basis of the CpG O/E prediction and experimental validation. A significant positive linear correlation was observed between the stage-specific expressions of PxDNMT1 and DNA methylation levels (5mC content). Particularly, high levels of DNA methylation and gene expression of PxDNMT1 were observed in eggs and mature females of P. xylostella. After host transfer of P. xylostella from Raphanus sativus to Arabidopsis thaliana, we identified some potential genomic loci that might have changed methylation levels. Using the method of fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP), we also found the corresponding genes primarily involved in neural system and signaling. The expressions of six candidate genes were verified by qRT-PCR. One of the genes, Px009600, might be regulated by a DNA methylation-mediated mechanism in response to host transfer. Our study provides evidence for a functional system of DNA methylation in P. xylostella and its possible role in adaptation during host transfer. Further studies should examine methylation as responsive factors to different host plants and environmental cues in insect pests.