Characterization of Brazilian populations of Pratylenchus brachyurus using morphological and molecular analyses

Abstract

In Brazil, Pratylenchus brachyurus damages economic important crops and it is managed with non-chemical methods such as crop rotation or resistant cultivars. However, the variability in reproduction and damaging effects observed among P. brachyurus populations could limit the efficacy and long lasting effect of nematode control practices. Twelve populations of P. brachyurus from different geographical areas of Brazil were analyzed morphologically and molecularly. The morphological and morphometric characters of the populations studied were variable, but fitted those of P. brachyurus. Assemblages of populations with different host preferences and reproductive capabilities were revealed by PCA of these populations using selected morphological characters. Phylogenetic analysis using ITS-rDNA sequences distinguished statistically supported groups of sequences that matched those of other populations of P. brachyurus deposited in the GenBank, confirming the identity of populations here studied. Intraspecific sequence diversity was observed among the populations. These variant sequences suggest the presence of microheterogeneity between ITS-1 copies in individuals. The findings of this study did not provide evidence of cryptic species in the P. brachyurus populations studied. The variability within and among populations of P. brachyurus observed in this work must be taken into consideration in breeding programs for resistance to this nematode.