مطالعه مولکولی، ریخت سنجی و ریخت شناسی دو گونه از جنس Psilenchus de Man, 1921 (Nematoda: Psilenchidae) از استان لرستان

Nematodes belonging to the genus Psilenchus are weak parasites of plants and mosses that feed on hairy roots, rhizoids and epidermal cells. Members of this genus were placed under the family Psilenchidae in 1986 and were subsequently transferred into the family Tylenchidae in 1987. Having two reproductive tracts and phasmids delimit this genus and its relatives from the traditional Tylenchidae and molecular phylogenetic studies using ribosomal markers apprive their placement inside the independent family Psilenchidae. So far, 21 species have been described under the genus Psilenchus and molecular sequences have been registered only for four species in the GenBank database. To study the diversity of species of the genus Psilenchus, a total number of 100 soil samples were collected from the rhizosphere of trees in Khorramabad county, Lorestan province. The nematodes were extracted using the Whitehead tray method and the samples were fixed using De Grisse method. Identification of nematodes was conducted using valid keys and literature. Molecular phylogenetic studies were performed using sequences of the D2-D3 expansion domains of 28S rDNA. Based on morphological and morphometric data, two species of the genus Psilenchus, namely P. curcumerus and P. vinciguerrae were identified. For molecular studies, one and two sequences were obtained for these species, respectively. In pairwise comparisons of the sequence of P. curcumerus with the sequences of this species previously available in the GenBank database, only one mismatch was observed. Based on the observed variation in tail shape of P. vinciguerrae (filiform to clavated tip), two sequences belonging to the specimens having the abovementioned tail tip shapes were compared, and no difference was observed between them. Comparison of the sequences of this species with two sequences of the same species in the GenBank, showed two mismatches.