Cytogenetics of Disomics, Monotelo- and Monoisodisomics and ml st Mutants of Chromosome 4 of Cotton.

The linkage relationships and arm locations of the ml(1) and st(1) mutants of cotton were determined with the use of monotelodisomics, a monoisodisomic and disomics. The ml(1) st(1) mutants are more than 50 cM apart on chromosome 4. The ml(1) locus is in the short arm and 16 cM from the centromere, and st(1) is in the long arm and 48 or more cM from the centromere. Recombination in the monoisodisomic was twice the expected value and higher, but not significantly, than in its monotelodisomic counterpart. It was concluded that the increase indicates a greater frequency of proximal exchange in the monoisodisomic than in the monotelodisomic.