QTL Controlling Cell Wall Composition in Biparental Population of Switchgrass.

Enhancing enzymatic hydrolysis of cellulose by minimizing the lignin content will maximize the ethanol yields from plant biomass and reduce the processing cost. A full-sib switchgrass (Panicum virgatum L.) mapping population consisting of 251 genotypes developed from a lowland AP13 and upland VS16 cross has been evaluated at three locations (Ardmore and Burneyville, Oklahoma, and Athens, Georgia) since 2008. Biomass harvested after senescence in 2009 and 2010 was evaluated for lignin content and sugar release. Biomass samples from all six environments were analyzed at the National Renewable Energy Laboratory (NREL) for lignin content, S/G ratio using molecular beam mass spectrometry (MBMS) and sugar release characteristics by co-saccharification. Significant differences were observed among the genotypes and the environments for the traits. The lignin content ranged from 19-27% of the dry biomass while the glucose and xylose release ranged from 120-313 and 123-263 mg g^-1, respectively. Regression analysis of the sugar release on the lignin content found that a unit increase in lignin content decreases total sugar release up to 10 mg g ^-1. Several genomic regions and loci underlying these variations were detected in the lowland and upland genetic linkage maps.