Quantitative Trait Loci and Trait Correlations for Maize Stover Cell Wall Composition and Glucose Release for Cellulosic Ethanol

In cellulosic ethanol production, the efficiency of converting maize (Zea mays L.) stover into fermentable sugars partly depends on the stover cell wall structure. Breeding for improved stover quality for cellulosic ethanol may benefit from the use of molecular markers. However, limited quantitative trait loci (QTL) studies have been published for maize stover cell wall components, and no QTL study has been published for glucose release (GLCRel) from stover by a cellulosic ethanol conversion process. Our objectives were to characterize the relationships among stover cell wall components and GLCRel, and to identify QTL with major effects, if any, influencing stover cell wall composition and GLCRel. Testcrosses of 223 intermated B73 x Mo17 recombinant inbreds and the parent lines were analyzed for cell wall composition and GLCRel after acid pretreatment and enzymatic hydrolysis. As expected, glucose (GLC), xylose (XYL), and Klason lignin (KL) composed the bulk (similar to 72%) of the stover dry matter. Significant genetic variance and moderate heritability were observed for all traits. Genetic and phenotypic correlations among traits were generally in the favorable direction but also reflected the complexity of maize stover cell wall composition. We found 152 QTL, mostly with small effects, for GLCRel and cell wall components on both a dry matter and cell wall basis. Because no major QTL were found, methods that increase the frequency of favorable QTL alleles or that predict performance based on markers would be appropriate in marker-assisted breeding for maize stover quality for cellulosic ethanol.