GENETIC VARIABILITY AND PHYLOGENETIC ANALYSES OF NACOBBUS ABERRANS SENSU LATO POPULATIONS BY MOLECULAR MARKERS

Genetic variability of Mexican Nacobbus aberrans populations was detected by ISSR markers and some genes used in taxonomic studies. The populations of N. aberrans were isolated from different hosts in Guanajuato and Michoacan (Mexico). Partial sequences analysis of the 18S, Internal Transcribed Spacer (ITS) and Cytochrome Oxidase I (COI) regions was used in order to identify and estimate the variability in nematode populations studied. Several inter-simple sequence repeat (ISSR) markers were developed with four anchored primers for the comparative study of genetic variation. According to the ISSR analysis, 88.12% out of 150 bands were polymorphic. This technique grouped populations into two main clusters revealing a high level of genetic variability separating the Romita population from the others, with genetic similarity indices ranging from 0.44 to 0.82. Analysis based on partial sequences of the 18S and ITS regions indicated that our populations of nematodes corresponded to N. aberrans. However, the mitochondrial gene revealed significant levels of variation among the sequences analyzed showing 16 variable sites. These results suggested that, in the sampled areas, there are at least two different biotypes of N. aberrans.