Species Identification by RAPD Analysis of Grain Amaranth Genetic Resources

Abstract

The grain amaranths (Amaranthus spp.) were important food staples of ancient American civilizations, and are still important in contemporary Latin America. Because of their nutritional value, the grain amaranths have received significant attention in recent years. Three species predominate among cultivated grain amaranth species: Amaranthus caudatus L., A. cruentus L., and A. hypochondriacus L. Due to variation for morphological characters, accurate classification of amaranth genetic resources is not always possible. The objective of this study was to determine if random amplified polymorphic DNA (RAPD) markers could be used to classify accessions by species. Twenty‐nine previously classified accessions were used as standards. An additional 82 previously unclassified accessions were also investigated. DNA samples from each species were bulked to use as standards for RAPD marker selection. A total of 29 polymorphic RAPD fragments identified in the bulked DNA standards were further tested on all accessions individually. Cluster analysis of RAPD markers separated the 29 known accessions into three distinct groups that corresponded to the morphological species identifications. A species designation was also assigned to all previously unclassified accessions by RAPD analysis. Analysis of 282 polymorphic fragments generated from 80 primers among bulked DNA samples revealed that A. hypochondriacus and A. caudatus are genetically more similar to each other than either species is to A. cruentus. These results suggest that RAPD analysis can be used to efficiently classify grain amaranth accessions by species.