RAPD variations in selected and unselected blue grama populations

Blue grama (Bouteloua gracilis H.B.K. Lag. ex Steud.) is one of the most widespread native grasses in western North America. Little is known about the genetic diversity of this species and the genetic shift in selected populations. Random amplified polymorphic DNA (RAPD) markers were used to assess the genetic variations of blue grama plants in 11 natural source populations (SPs) in southern Manitoba and two selected populations. Population 'BMSC' was a balanced multisite composite of 99 clones selected for higher seed yield from the 11 SPs. Population 'MSC' was a mass-selected composite of 25 clones with higher seed yield from eight SPs. Twelve RAPD primers were used to assay 108 original propagules from the 11 SPs and 96 seedlings from each selected population. A total of 69 polymorphic RAPD bands were detected. No unique RAPD bands were found for any SPs and 97.8% of the total RAPD variation was detected within SPs. Variation in RAPD markers was not associated with geographical distances. Highly significant changes in RAPD band frequency from their SPs were detected in both selected populations, but only MSC displayed the fixation of polymorphic bands. The estimated genetic shifts were small, 0.6% for BMSC and 1.9% for MSC.