Genome Size and Chromosome Analyses in Prairie Cordgrass

The next generation of bioenergy crops will be grown on marginal lands. Prairie cordgrass (Spartina pectinataLink) is well suited to marginal land because of its tolerance to stresses such as salinity and water fluctuations. Developing prairie cordgrass as an energy crop requires genomic information such as genomic size and ploidy level. The 2C nuclear genome size of 11 prairie cordgrass populations, originating from Illinois, North Dakota, and South Dakota, were determined by flow cytometry using somatic G1 nuclei, and the ploidy variation confirmed by counting the chromosome number. One population from each of North Dakota and South Dakota, as well as the Red River, had genome sizes of 3.1 pg of DNA per G1 somatic nucleus whereas, the majority of the eight populations from Illinois had a genome size of 1.6 pg. One plant from one of the Illinois populations had an estimated genome size of 2.3 pg. These genome sizes of 3.1 and 1.6 pg, along with their respective chromosome numbers of 80 and 40 indicate octoploid and tetraploid plants. The chromosome number of 60 observed in the plant with 2.3 pg indicated that this plant was hexaploid. This study provides the first estimates of genome size for prairie cordgrass and is also the first to report observed hexaploidy in this species. This genomic information provides critical knowledge for designing efficient breeding schemes for plant improvement.