Feasibility analysis of Arabidopsis thaliana as an alternative host for research on interactions of pinewood nematodes with plants

Bursaphelenchus xylophilus causes pine wilt disease and substantial economic losses. However, as Pinus has some limitations as a host for studies, information about the interactions between B . xylophilus and Pinus at the molecular level is limited. The use of an alternative plant would greatly facilitate a better understanding of the plant-nematode interactions. In this study, we explored the feasibility of Arabidopsis thaliana as an alternative host to investigate the relationship between plants and B . xylophilus and established a system for the efficient infection of A . thaliana by B . xylophilus (defined in this paper as the mean number of plants infested with B . xylophilus ) by evaluating the artificial wounding of seedlings, ages of seedlings and nematode inoculum concentrations, and then the susceptibility of nine A . thaliana ecotypes was tested. The results showed that B . xylophilus infected all ecotypes tested. Artificially wounding the petiole of the first leaf increased the plant infection rate of B . xylophilus , reaching 90 % of the inoculated plants with inoculum concentration of 400 nematodes per plant at 15 days after germination (DAG). A typical symptom was yellowing of the entire plant and browning of older leaves 72 h after inoculation. Membrane damage of the thylakoid lamellae, collapse of chloroplasts and increase of the electron density of the cytoplasm were also observed. Our results demonstrated that B . xylophilus could invade Arabidopsis and cause similar early symptoms to that of pine trees, yet B . xylophilus could not reproduce in A . thaliana . Nonetheless, A . thaliana may be used to study the early response of plants to B . xylophilus and it provides a new opportunity for studying B . xylophilus -plant interactions.