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Variation at the molecular level of reniform nematode populations in Alabama

Tilahun, Y., Zipf, A., Deng, D., Sharma, G., Soliman, K., McLean, K., Jenkins, J.
Proceedings of the Beltwide Cotton Conferences 2003 pp. A13
cotton, Rotylenchulus reniformis, animal genetic resources, DNA, molecular cloning, population genetics, polymerase chain reaction, ribosomal RNA, phylogeny, Gossypium, plant parasitic nematodes, highlands, nematode control, Alabama
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 in developing genetic resistance in the crop; however, there are no cultivars of Upland cotton available which are resistant to reniform nematodes. Prior to focusing on biological resistance, it is important to assess molecular and physiological differences which may exist within the species, indicating a possible conflict with resistance strategies. Different populations of reniform nematodes were collected from 6 wide spread counties in Alabama. Nematodes were extracted from soil and DNA was isolated, subjected to PCR, cloning, and sequencing. PCR utilized primers spanning from a ribosomal RNA region - 18S rRNA region. Alignment of clonal sequences showed both inter- and intra-population differences. A phylogram of 18S sequences revealed 3 superclusters, with two being more closely related than the other. Each cluster could not be traced to a single 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 information of reniform nematode.