Inhibition response of Pinus densiflora clones to Bursaphelenchus xylophilus systemic dispersal and their resistance to pine wilt disease

Abstract

AbstractTo determine the relationship between resistance to pine wilt disease and the inhibition of nematode systemic dispersal in Pinus densiflora, a suspension of 200 Bursaphelenchus xylophilus was placed on the upper cut end of 5-cm-long, living or boiled branch sections of 17 clones of pine that had different resistance levels. Significantly more nematodes passed through boiled sections than living sections during 24 h. Living branches of the resistant P. densiflora clone group significantly suppressed the dispersal of B. xylophilus compared with those of the susceptible group, suggesting that the inhibition of nematode systemic dispersal was involved in the resistance mechanism of selected disease-resistant pine clones. However, there was no significant correlation between the resistance class and the mean number of nematodes passing through live branch sections within the resistant clone group. The reason for the lack of correlation is discussed in relation with the resistance mechanism.