Functional analysis of the venom allergen-like protein gene from pine wood nematode Bursaphelenchus xylophilus using a baculovirus expression system

•Recombinant venom allergen-like protein (VAP) was obtained and by expressing Bx-vap-1 in insect cells.•Three-year-old Pinus massoniana were inoculated with recombinant VAP, simulating B. xylophilus esophageal gland secretions.•We examine the changes of the α-pinene synthase gene expression and α-terpene content of P. massoniana after inoculation.•We detected the pathological, Cytological and cavitation changes of the pine branch 15d post inoculation.•The recombinant VAP could damage P. massoniana cells. Recombinant VAP did not, however, lead to cavitation.

The pine wood nematode, Bursaphelenchus xylophilus, infects pine trees, leading to fatal pine wilt disease. Here, recombinant venom allergen-like protein (VAP) was obtained by expressing Bx-vap-1 in insect cells. Three-year-old Pinus massoniana were inoculated with recombinant VAP, simulating B. xylophilus esophageal gland secretions. Recombinant VAP up-regulated α-pinene synthase gene expression, the trees showed disease symptoms 15 d after inoculation and the xylem pith revealed brown tissue discoloration, indicating that recombinant VAP could damage P. massoniana cells. Recombinant VAP did not, however, lead to cavitation, indicating that the VAP secreted from B. xylophilus acts as a defense response elicitor.