Morphological and molecular characterization of root-knot nematodes from Uzbekistan

Plant-parasitic nematodes are of great economic importance as widespread harmful plant pests of the world. Among them, root-knot nematodes, especially species of the genus Meloidogyne, cause significant damage to agriculture. In this paper the species composition, morphological and molecular genetic characteristics of root-knot nematodes in vegetable crops of the Zarafshan Valley of Uzbekistan were studied. As a result of morphological studies, three species belonging to the genus Meloidogyne were found in Samarkand region of the Zarafshan Valley; these species were Meloidogyne javanica, M. incognita and M. hapla identified by concentric lines in the anal-vulvar part of sexually mature female nematodes. The results show that the anal arch of M. javanica and M. hapla is low, and that of M. incognita is high. In order to additionally characterize the species of the discovered root-knot nematodes, we carried out their molecular identification. However, nucleotide sequence analysis in the 5S–ITS2 region of rDNA showed no differences between M. javanica and M. incognita, the overall difference being to 0.6%. These data indicate that both these taxa belong to the one species based on 5S–ITS2 region, but this datum should be supplemented by additional research with other genes. The sequence differences between the species M. javanica or M. incognita with species M. hapla amounted to 23%. Species analysis based on the analysis of morphological and molecular genetic indicators of root-knot nematodes is important because it was conducted for the first time in Central Asia. The studies conducted indicate that M. hapla, M. javanica and M. incognita are common on tomato farms in Payaryk, Akdarya and Jambay districts of Samarkand region of Uzbekistan.