Stage-specific transcriptome of Bursaphelenchus xylophilus reveals temporal regulation of effector genes and roles of the dauer-like stages in the lifecycle

The pine wood nematode Bursaphelenchus xylophilusis the causal agent of pine wilt disease, one of the most devastating forest diseases in East Asian and West European countries. The lifecycle of B. xylophilusincludes four propagative larval stages and gonochoristic adults which are involved in the pathogenicity, and two stages of dispersal larvae involved in the spread of the disease. To elucidate the ecological roles of each developmental stage in the pathogenic life cycle, we performed a comprehensive transcriptomeanalysis using RNA-seqgenerated from all developmental stages of B. xylophilusand compared transcriptomesbetween stages. We found more than 9000 genes are differentially expressed in at least one stage of the life cycle including genes involved in general nematode biology such as reproduction and moultingbut also effector genes likely to be involved in parasitism. The dispersal-stage transcriptomerevealed its analogy to C. elegans dauer and the distinct roles of the two larval stages from each other regarding survival and transmission. This study provides important insights and resources to understand B. xylophilusparasitic biology.