Location: Plant Science ResearchTitle: Strategies for using molecular markers to simultaneously improve corn grain yield and stover quality for ethanol production Author
|Jung, Hans Joachim|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2011
Publication Date: 4/10/2011
Citation: Bernardo, R., Jung, H.G., Massman, J.M., Lewis, M.F., Lorenzana, R.E. 2011. Strategies for using molecular markers to simultaneously improve corn grain yield and stover quality for ethanol production [abstract]. USDA-DOE Plant Feedstock Genomics for Bioenergy Awardee Meeting, April 10-13, 2011, Crystal City, Virginia. Abstract No. 135. p. 104. Interpretive Summary:
Technical Abstract: About 235 million metric tons of corn (Zea mays L.) stover (i.e., stalks, leaves, cobs, husks, and tassels) are left unharvested in U.S. corn fields each year. This stover represents a most abundant source of lignocellulosic substrate that can be converted to ethanol biofuel. But although today's corn hybrids have been aggressively bred for grain yield, they have not been bred for stover-quality traits important for ethanol production. Here, our objective was to optimize the use of DNA markers to simultaneously breed for high corn grain yield (for non-energy and energy uses) and high stover quality for ethanol production. We used SNP markers combined with classical quantitative-trait analyses to study the extent to which grain yield, agronomic traits, and stover quality can be simultaneously improved in the B73 x Mo17 corn population. Three stover-quality traits were measured: concentration of cell wall glucose in dry stover ("Glucose"); cell wall glucose released from the stover by thermochemical pretreatment and enzymatic saccharification ("Glucose Release"); and concentration of lignin on a cell-wall basis ("Lignin"). Genetic variances were significant for grain yield, moisture, stalk and root lodging, plant height, and all three stover-quality traits. Heritabilities of the stover quality traits were 0.57 for Glucose, 0.63 for Glucose Release, and 0.68 for Lignin. Genetic and phenotypic correlations among traits were generally favorable but also reflected the complexity of corn stover cell wall composition. We found 152 QTL, mostly with small effects, for Glucose Release and cell wall components on both a dry matter and cell wall basis. Because no major QTL were found, we expected that methods that predict performance based on markers, such as genomewide selection, would be appropriate in marker-assisted breeding for these traits. Responses to three cycles of selection for Glucose, Glucose Release, and Lignin were higher with genomewide selection (which utilized all markers rather than only those with significant effects) than with selection based only on significant markers. To our knowledge, this represents the first report of the usefulness of genomewide selection based on empirical data in plants. We conclude that current corn-breeding programs should be able to incorporate stover quality for cellulosic ethanol as a breeding objective, without having to use unadapted or exotic germplasm and without adversely affecting genetic gains for grain yield and agronomic traits. Given the absence of major QTL and the complexity of the traits, we recommend genomewide selection for the improvement of stover-quality traits for cellulosic ethanol in corn.