Monday, November 13, 2006

Genetic Diversity of Blue Grama Grass as Revealed by Simple Sequence Repeats.

Jonathan Kahler and Leo Schleicher. South Dakota State University, Brookings, SD 57006, United States of America

Blue grama grass (Bouteloua gracilis [H.B.K.] Lag. ex. Steud.) is currently being selected for use as a low-input turfgrass.  Understanding the amount and extent of genetic variation within and among wild populations of blue grama would be useful for turf and forage grass genetics and breeding programs.  Morphological markers have not been found to be useful and molecular markers have not previously been identified for use in determining the amount of genetic diversity within and between populations of blue grama.  However, SSR markers have been used in marker facilitated breeding programs to develop improved cultivars of major cereal crops including corn, wheat, rice, sorghum, and barley.  The goal of this study is to identify polymorphic molecular markers and to use the markers to genetically characterize wild populations of blue grama.  Specific objectives of this study were to 1) Select SSR’s previously identified in related grass species and screen them for amplification in blue grama; 2) Select polymorphic markers and screen them on plants collected from wild populations; and 3) Calculate genetic distances.  Samples were collected from wild South Dakota populations.  DNA was extracted from individual leaf blades and was amplified using PCR.  Amplicons were separated using agarose gel electrophoresis.  Four hundred SSR’s were selected based on chromosomal distribution, number of alleles per locus, and heterozygosity from the original species.  The 400 markers were assayed and polymorphic markers were included in the genetic distance analysis.  Early results of this study have shown that a considerable number of SSR markers identified in related grass species are syntenous to blue grama.  Genetic distance analysis provided information on genetic variability within and between these populations.  These markers will be useful for future linkage and mapping studies as well as for molecular marker facilitated selection in blue grama breeding programs.