Identification of putative genomic regions controlling recalcitrance in AP13 x VS16 switchgrass population

Switchgrass cell-wall recalcitrance is the decisive scientific challenge for bioethanol production from biomass feedstock. A full-sib switchgrass mapping population derived from a cross between a lowland genotype, AP13, and an upland genotype, VS16, was used for the construction of genetic linkage maps. The female and male genetic maps were constructed with 522 and 405 loci at a density of 3.7 and 4.8 cM per marker, respectively. The population was evaluated at three locations (Ardmore and Burneyville, OK and Athens, GA) for agronomic performance and composition qualities. Biomass samples collected at the end of the 2009 growing season from all locations were evaluated at NREL for lignin content, S/G ratio, and sugar release characteristics. Significant genotypic differences were recorded for all traits at all locations. However, genotype-by-environment interactions were found not significant.  QTL analysis for lignin and sugar release on the female parental map identified 4, 3, and 2 QTLs for lignin content at Ardmore, Burneyville and Athens, respectively. A total of 9, 4, and 7 QTLs were mapped for glucose, xylose and total sugar release, respectively. Favorable marker alleles increased sugar release by 2-8%. Contribution of male parent on the expression of these traits will be assessed. Markers identified in this project will be useful to develop better switchgrass feedstock through marker-assisted selection.