Amplified Fragment Length Polymorphism Marker Diversity among High Yielding Perennial Alfalfa (Medicago sativa L.) Core Collection Accessions

Understanding the genetic structure of alfalfa (Medicago sativa L.) plant introductions, including the identification of divergent populations, may benefit their utilization in cultivar development programs. Two independent experiments (Exp. 1 and Exp. 2) were conducted to assess amplified fragment length polymorphism (AFLP) marker diversity among 18 high-yielding alfalfa core collection accessions that were previously evaluated by diallel analysis for forage yield combining abilities and heterosis in southern New Mexico. Each experiment involved nine different M. sativa subsp. sativa populations and one control accession of M. sativa subsp. falcata (L.) Arcang. Both experiments indicated that the M. sativa subsp. sativa populations were genetically distinct from the M. sativa subsp. falcata accession. Genetic distances among the M. sativa subsp. sativa accessions were predominantly governed by the geographic distances of their historic origins in Exp. 1. In Exp. 2 such relationships were less obvious, perhaps because multiple accessions possessed South American and/or central Asian lineage. Genetic distances in both experiments were also influenced by the intersubspecific or intrasubspecific hybrid nature of some accessions. Multiple correspondence analysis of the AFLP data for the 18 accessions, in conjunction with yield performance and heterosis response of their diallel hybrids, indicated that most hybrids that exhibited positive heterosis and high yield possessed a genetically divergent accession as a parent.