Similarities and differences between Amaranthus species and cultivars and estimation of outcrossing rate on the basis of electrophoretic separations of urea-soluble seed proteins

The methods of distinguishing Amaranthus species and cultivars and assessment of outcrossing rate in grain amaranths are proposed. The collection of 20 cultivars and accessions of 7 species (A. tricolor, A. mantegazzianus, A. cruentus, A. caudatus, A. hypochondriacus, A. hypochondriacus x A. hybridum and A. paniculatus) was examined. Urea-soluble proteins both from bulked samples (20 seeds) of particular cultivars, and samples which were obtained by mixing together cultivars of each species were extracted. To estimate the outcrossing rate, the proteins were extracted from each of 100 seeds of cultivar A10 (A. caudatus). In this case seeds were collected both from isolated inflorescences and from flowers exposed to open-pollination. The electrophoretical separations of proteins (SDS-PAGE) were performed. The protein pattern of 56-64 bands was detected. The samples were classified to three groups: 1- A. caudatus and A. cruentus, 2- A. tricolor and A. mantegazzianus and 3- A. hypochondriacus, A. hypochondriacus x A. hybridus and A. paniculatus. All species can be distinguished from each other. The protein pattern of A. tricolor (leafy type of amaranths) is considerably different from other species. The present study suggests a closer similarity between A. caudatus and A. cruentus than between the pairs of species A. hypochondriacus/A. caudatus and A. hypochondriacus /A. cruentus. Only small differences were seen between cultivars, nevertheless they were sufficient for distinguishing all the cultivars. It is possible to detect outcrossing between cultivars, by observing that 30% of 'A10' seeds performed other patterns of proteins. Electrophoretic analysis of seed proteins proved to be useful for distinguishing species and cultivars of Amaranth, for describing similarity between species and for estimation its outcrossing rate.