Genetic Relationships among Smooth Bromegrass Cultivars of Different Ecotypes Detected by AFLP Markers
- Yasas S. N. Ferdinandez and
- Bruce E. Coulman *
Smooth bromegrass (Bromus inermis Leyss.), the most commonly cultivated perennial bromegrass species in North America, belong to three ecotypes; northern, intermediate, and southern. The objective of this study was to analyze the genetic relationships of cultivars belonging to these ecotypes by amplified fragment length polymorphic (AFLP) markers. Seven AFLP primer combinations produced 176 polymorphic markers, which occurred in different frequencies in different cultivars, with no ecotype or cultivar specific markers. Cluster analysis and principle component analysis grouped the cultivars according to their pedigrees rather than by ecotypes. The southern cultivars (Baylor, Lincoln, Beacon, and Blair), older cultivars developed in Iowa and Nebraska, grouped distantly to the rest of the cultivars. The recently developed southern type cultivars (Badger, Alpha, and Radisson) were grouped closely with the intermediate type cultivars (Magna and Signal). The northern type cultivars (Carlton, Jubilee, and S-7133) grouped with the recently developed southern and intermediate cultivars. The close association of the recently developed southern cultivars to the intermediate and the northern cultivars but distinct from the older southern cultivars may indicate introgression of northern ecotype germplasm into the former. Analysis of molecular variance (AMOVA) of the 14 cultivars indicated a higher within-population variation (85%) than the among-population variation (15%). Higher molecular variations observed in the recently developed southern and some northern cultivars reflect the diverse genetic backgrounds of the source populations. The older southern cultivars showed the lowest molecular variation due to the narrow genetic background of the source populations. This study shows that AFLP markers can be used to differentiate phenotypically similar smooth bromegrass cultivars according to their breeding history, which will aid in future smooth bromegrass breeding projects.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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