An assessment of genetic relationships within the genus Digitalis based on PCR-generated RAPD markers

RAPD markers were used to study inter-specific variation among six species of the genus Digitalis: D. obscura D. lanata, D. grandiflora, D. purpurea, D. thapsi and D. dubia, and the hybrid D. excelsior (D. purpurea x D, grandiflora). A total of 91 highly reproducible bands amplified with four arbitrarily chosen decamer primers were obtained. Homology of the coemigrating RAPD markers was tested by blot hybridisation and sequencing of selected bands. The application of a range of statistical approaches for RAPD data analysis, including distance and parsimony methods, family clustering and the analysis of molecular variance (AMOVA), indicated that these molecular markers were taxonomically informative in Digitalis. The species relationships revealed were fully consistent with those previously obtained using morphological affinities. The hy brid D. excelsior seems to have stronger affinity to the section Digitalis than to Grandiflorae. This is the first known report of the application of RAPD markers for the study of genetic relationships among species of the genus Digitalis.