Molecular variability and phylogenetic Relationships of pratylenchus species by using the its rdna

Root-lesion nematodes of the genus Pratylenchus are migratory endoparasites distributed worldwide and regarded as severe constraints of economic crops. Crop damage is often aggravated by their interactions with soilborne fungi and bacteria, resulting in complex diseases which are biological and physiological rather than physical in nature. Morphological identification and species delimitation of these nematodes is still problematic due to their high morphological plasticity, the small number of diagnostic features available at species level, the intraspecific variability of some of these characters and many incomplete descriptions published in the literature. Thus, molecular approach, by using the ribosomal DNA, plays a key role within the taxonomy of this genus. The ITS containing region of eighteen species of Pratylenchus was sequenced and the variation within and between species was assessed. Phylogenetic analyses were conducted by using different tree reconstruction approaches: Bayesian inference (BI), neighbour-joining Log-Det (NJ), maximum parsimony (MP) and maximum likelihood (ML). The alignment revealed small species-specific DNA sequences suitable for the construction of potentially useful species- specific primers or for a more promising approach for DNA barcoding of root-lesion nematodes.