Quantitative trait loci can be identified through linkage with biochemical or morphological markers; however, cotton has an insufficient number of genetic markers to be useful in searching for linkages with quantitative trait loci. The existing markers can be supplemented with new types of markers derived from DNA polymorphisms. One type of these markers is restriction fragment length polymorphisms (RFLP's). RFLP's offer the benefits of being present in large numbers, genetically stable, and codominantly inherited.

Sixty-nine lines of cotton were chosen for their diversity. Two restriction enzymes (Eco RI and Eco RV) were used to digest DNA. The lines were evaluated with a total of 101 combinations of probe and endonuclease. Seventy-five probe enzyme combinations produced well defined bands on the film with 179 polymorphic fragments present.

The data indicates that RFLP's should be useful for developing additional genetic markers in cotton. There were fewer polymorphisms found between closely related lines than distantly related lines. This indicates that there is some relationship between the number of polymorphisms and diversity among lines. This study is continuing with F2 populations from crosses involving diverse lines.