RAPD marker variation among smooth bromegrass cultivars

ne level of genetic diversity within and among smooth bromegrass (Bromus inermis Leyss.) cultivars and land races is unknown. The objective of this study was to investigate and characterize genetic diversity of smooth bromegrass cultivars and selected populations on the basis of random amplified polymorphic DNA (RAPD) markers. Variation among 277 individual plants from 40 smooth bromegrass cultivars was evaluated by means of RAPD markers. Nineteen primers evaluated amplified 97 informative amplicons. Several RAPD marker bands showed unique patterns of mean frequency differences among germplasm groups. A dendrogram constructed from average linkage cluster analysis did not indicate any clear pattern of division on the basis of discrete or putative climatype or adaptation zones. There was considerable correspondence to known pedigree relationships revealed from a previous smooth bromegrass morphological clustering analysis, particularly for lines that are closely related to each other. The two interspecific hybrids between B. inermis and B. pumpellianus Schribner (Polar) and B. riparius Rehm. (S-9183-H) did not exhibit any species-specific markers. All groups of smooth bromegrass germplasm were found to have high within-population genetic variation that ranged from 84 to 96% of the total, reflecting the outcrossing reproduction and probably the complex inheritance of smooth bromegrass. Analysis of molecular variance showed the largest interpopulation genetic variation for contemporary germplasm sources, supporting morphological studies for the existence of genetic variability among contemporary smooth bromegrass germplasms. These results suggest that landrace cultivars likely remain useful for germplasm improvement and cultivar development.