Genetic Diversity in Tetraploid Switchgrass Revealed by AFLP Polymorphisms.

Switchgrass (Panicum virgatum L.) is a perennial grass native to North America, which has been identified as a dedicated biofuel crop. Traditional breeding techniques are currently being utilized to increase its biomass yield. Long term improvement in breeding requires a high level of diversity in the germplasm. The objectives of this study were to quantify genetic diversity in tetraploid switchgrass germplasm collected at Oklahoma State University, and to characterize genetic relatedness among the collections from distinct regions. Fifty six tetraploid accessions including upland and lowland ecotypes from Arkansas, Florida, Kansas, Maryland, Mississippi, Missouri, Nebraska, New Jersey, North Carolina, Oklahoma and Tennessee were used in the investigation. Genomic DNA samples were isolated for each clonal accession using Zymo Research Plant/Seed KitTM. Fluorescence-labeled amplified fragment length polymorphism (AFLP) procedure was utilized to generate DNA profiling patterns. Amplified fragments were visualized using a Li-Cor 4300 DNA Analyzer and scored visually. Fourteen selective AFLP primer combinations were used to amplify polymorphic bands for the switchgrass collections. The accessions' genetic similarity coefficients, UPGMA (unweighted pair-group method with arithmetic averaging) cluster analysis, and principle coordinate analysis were performed using NTSYS-pc (ver. 2.02i) (Numerical Taxonomy System) software. A total of 435 polymorphic markers were detected. The genetic similarity coefficients (SC) ranged from 0.4160 to 0.8955.