Identification Of A New Species Similar To Bursaphelenchus Xylophilus

Pine wilt disease has caused great damage to the forestry and ecological system in China. It became the most destructive threat to pine wood production in our country. It is difficult to differentiate Bursaphelenchus xylophilus from some other Bursaphelenchus spp discovered from pine wood by morphological characters. The following work were carried out by using a Bursaphelenchus sp. from coniferous wrapper as researched material.A new species of Bursaphelenchus, B. longispiculis sp.n., from coniferous wrapper were identified. B. longispiculis sp.n., which came from Japan, is very similar to B. mucronatus and B. xylophilus, but the length of spicules is much larger than both of them. The value "a" and "c" of these three species are also shown distinct difference.ITS regions of B. longispiculis sp.n., B. xylophilus and B. mucronatus were amplified using universal primers, then their DNA sequence were obtained. The ITS sequences were aligned using software CLUSTAX. The alignment results show that the 5.8S fragment sequence of all species had few divergence except for B. abruptus which share a 14% divergence with other species. The interspecific divergences of ITS1 sequence range from 10 to 30% and that of ITS2 sequence range from 13 to 48% except for B. abruptus whose divergences of ITS1 and ITS2 regions with other species is more than 50%. The divergences of ITS1 region between B. longispiculis sp.n. and other species range from 23 to 28%, and those of ITS2 region range from 33 to 43%.Phylogenetic trees were obtained using alignment results. The NJ analysis results in ITS1, ITS2 and composite datasets show that B. longispiculis sp.n. had long genetic distance from other species and support B. longispiculis sp.n. as a distinct , well separated clade.B. longispiculis sp.n. were tested for pathgenicity to 2-year old seedlings of Pinus thunbergii and P. massoniana. And testing results show that B. longispiculis sp.n. has very weak pathgenicity to the seedlings of Pinus thunbergii and no pathgenicity to the seedlings of Pinus massoniana.