Genetic Variation in Native Perennial Grass, Spartina pectinata

Prairie cordgrass (Spartina pectinata Link) is a warm-season perennial grass and indigenous throughout most of the continental United States and Canada.  Prairie cordgrass has been used in conservation practices for stream bank stabilization and riparian vegetation and is recently gaining attention as a cellulosic bioenergy crop in marginal land with its tolerance to abiotic stresses, such as cold, soil salinity, and frequent flooding.  The objectives of this study were 1) to determine cytogeographic distribution and genome size variation in U.S. native populations of prairie cordgrass, 2) to differentiate cytotypes based on chloroplast DNA sequencing, and 3) to describe phenotypic variation, such as flowering, biomass yield, and growth habit.  We collected 130 natural populations from their natural habitats throughout eastern 2/3 of U.S.  We confirmed the existence of two previously reported ploidy levels [tetra- (2n = 4x=40), and octoploids (2n = 8x =80)] and also identified a previously unreported neohexaploid (2n = 6x =60).  Chloroplast DNA sequencing differentiated two haplotypes in octoploid cytotypes in the West North Central regions and three haplotypes in both tetra- and octoploid  cytotypes in Central and East Northern regions of USA.  Evaluation in the common garden nursery located in Urbana, IL showed extensive phenotypic variation and biomass yield potential.  Plant height and tiller mass were found to be the most important yield components.  Latitude of population origin was negatively correlated with the flowering time.  Plant height and tiller mass were increased with delayed flower time.  Our study reveals extensive genetic variation in indigenous prairie cordgrass that can be used to increase biomass production and stress tolerance during cultivar development.