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Poster: Biology & Disease Mgmt: Genetics of Resistance


SNP variation in switchgrass disease resistance genes
B. BAHRI (1), G. Daverdin (2), J. Cheng (3), K. Barry (3), S. Smith (4), K. Devos (5) (1) Dept. of Plant Protection, National Agronomic Institute of Tunisia/ Dept. of Crop and Soil Sciences, University of Georgia, U.S.A.; (2) Marucci Center for Blueberry

Switchgrass (Panicum virgatum L.), an allotetraploid perennial C4 grass native to North America, is an important feedstock for cellulosic biofuel production. Its high genotypic and phenotypic variation yield substantial potential for genetic improvement of bioenergy-related traits, including disease resistance. We studied SNP variation in 276 switchgrass genotypes, belonging to 36 accessions from mainly the Southern USA, across ~1 kb NBS-LRR regions of 4 classes of putative resistance (R) genes. PCR amplicons for an R gene with homology to the barley powdery mildew resistance gene Mla from 150 switchgrass accessions mapped to two homoeologous regions in the allotetraploid switchgrass genome. Reads from individual accessions aligned preferentially against only one locus. Fitfty-eight SNP positions and 78 haplotypes were recorded. Twelve SNPs were present in more than 35% of the accessions. Although switchgrass is largely an obligate outcrossing species, 95% of the SNPs were homozygous. The results indicate that selection for some potentially beneficial SNPs occurred in natural switchgrass population which were subsequently fixed in homozygous condition at the locus level