Cotton, a major crop in the world market, is grown mostly for fiber and is subject to many biotic stresses such as nematodes,particularly Rotylenchulus reniformis, the reniform nematode. The best method for combating reniform nematodes may be indeveloping genetic resistance in the crop; however, there are no cultivars of Upland cotton available which are resistant toreniform nematodes. Prior to focusing on biological resistance, it is important to assess molecular and physiological differenceswhich may exist within the species, indicating a possible conflict with resistance strategies. Different populations ofreniform nematodes were collected from 6 wide spread counties in Alabama. Nematodes were extracted from soil and DNAwas isolated, subjected to PCR, cloning, and sequencing. PCR utilized primers spanning from a ribosomal RNA region – 18SrRNA region. Alignment of clonal sequences showed both inter- and intra-population differences. A phylogram of 18S sequencesrevealed 3 superclusters, with two being more closely related than the other. Each cluster could not be traced to asingle population or region, indicating the genotypes were widespread. The variety of nucleotide base changes was unexpected,especially within a region (18S) considered highly conserved. This is the first report of genomic sequence informationof reniform nematode.
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