Detection of minisatellite sequences in Phaseolus vulgaris

An improved procedure for detecting minisatellite sequences in Phaseolus vulgaris is described. Both M13 protein III tandem repeat and the 33.15 human mini-satellite sequences revealed polymorphisms with a high number of sharp bands after digestion of genomic DNA with Hae III, Hinf I, or Taq I. Improved resolution of the numerous restriction fragments detected by these probes is accomplished by one or more of the following: varying agarose concentration, using high SDA hybridization buffer, exposure of the autoradiograph without intensifying screens, and transfer of the autoradiograph to electrophoresis paper. Increased stability of the DNA-DNA hybridizations with these heterologous probes is obtained by reducing hybridization temperature. Labeling probes with the polymerase chain reaction can accentuate some restriction fragments depending upon the radiolabeled nucleotide used.