Molecular characterisation and diagnostics of some Longidorus species (Nematoda: Longidoridae) from Russia and other countries using rRNA genes

The needle nematodes of the genus Longidorus can cause diseases of various crops and trees, and are comprised of more than 150 valid species. Eleven valid and six unidentified species of the genus Longidorus collected in different regions of Russia, two states of USA, Germany, New Zealand and Ukraine were molecularly characterized using analysis of the partial 18S rRNA and the D2–D3 expansion segments of the 28S rRNA gene sequences. Fifty-four partial 28S rRNA and fifteen partial 18S rRNA gene sequences were obtained for the present study. Using molecular criteria, we confirmed the morphological identification and distinguished between the following species: L. aetnaeus, L. africanus, L. andalusicus, L. artemisiae, L. caespiticola, L. distinctus, L. elongatus, L. euonymus, L. intermedius, L. leptocephalus and L. lignosus. Two longidorid populations from Russia and four from California were not identified to a species level. We obtained the full length D2–D3 of 28S rRNA gene sequence from several freshly-collected L. artemisiae samples. We confirmed the identity of the D2 region of 28S rRNA gene sequence with a short D2 of 28S rRNA gene fragment sequence previously obtained from formalin-fixed nematodes embedded in the L. artemisiae paratype slides. Longidorus lignosus was molecularly characterized and L. aetnaeus was reported from Russia for the first time. PCR-D2-D3-RFLP diagnostic profiles generated by five restriction enzymes: AluI, HinfI, Bsp143I, Tru1I and RsaI are presented for sixteen Longidorus species.