UGT440A1 Is Associated With Motility, Reproduction, and Pathogenicity of the Plant-Parasitic Nematode Bursaphelenchus xylophilus.

Pine wilt disease (PWD) caused by Bursaphelenchus xylophilus is considered a major threat to pine forests worldwide. Uridine diphosphate (UDP)-glycosyltransferases (UGTs) catalyze the conjugation of small lipophilic compounds with sugars and play crucial roles in the detoxification and homeostatic processes in all living organisms. We investigated the molecular characteristics and biological functions of the gene UGT440A1 that encodes UGTs in B. xylophilus. The in situ hybridization results indicated that UGT440A1 is expressed in all developmental stages of B. xylophilus, particularly in the head, intestine, and hypodermis of the second-stage of juveniles (J2), third-stage of juveniles (J3) and fourth-stage of juveniles (J4) females and in almost the whole body of J4 males and adults. Recombinant UGT440A1 was observed mainly in the inclusion bodies, and the enzyme activity assay revealed that UGT440A1 could catalyze the glycosylation reaction of two types of flavonols (kaempferol and quercetin). RNA interference (RNAi) of UGT440A1 suppressed motility, feeding, and reproduction of B. xylophilus. Furthermore, UGT440A1 knockdown caused a delay in the development of PWD symptoms in the pine seedlings inoculated with the nematodes. These results suggest that UGT440A1 is involved in the pathogenic process of B. xylophilus and the information may facilitate a better understanding of the molecular mechanism of PWD.

Transcriptomic profiling of Bursaphelenchus xylophilus reveals differentially expressed genes in response to ethanol.

Pinewood releases ethanol and other volatile compounds after Bursaphelenchus xylophilus infection. In the current study, we examined the influence of different ethanol concentrations on B. xylophilus reproduction. Low-concentrations of ethanol (8.5, 17, and 34 mM) increased egg production in B. xylophilus, whereas higher-concentrations (156 and 312 mM) reduced egg production. Transcriptome analysis was conducted to explore the molecular response of a low concentration of ethanol on the nematodes. The results suggest that the nematodes use ethanol as an energy source, which may promote survival. Ethanol induced changes in the expression of genes involved in the biosynthesis and metabolism of fatty acids and amino acids. Furthermore, ethanol promoted the expression of detoxification-related, cell wall-degrading, and reproduction-related genes. Such responses might contribute to the pathogenicity of B. xylophilus.