INVESTIGATORS: R. Bernardo, H.-J. G. Jung
INSTITUTIONS: University of Minnesota; USDA-ARS
NON-TECHNICAL SUMMARY: Corn is the major crop in the U.S., with 275 million metric tons of grain harvested each year for feed, food, and industrial uses. An estimated 235 million metric tons of corn stover (i.e., stalks, leaves, cobs, husks, and tassels) are left unharvested in U.S. cornfields each year. This stover represents a most abundant source of lignocellulosic substrate that can be converted to ethanol biofuel. But while today's corn hybrids have been aggressively bred for grain yield, they have not been bred for stover-quality traits important for ethanol production. This research will lead to answers to the key questions "Can corn be bred for both grain yield and lignocellulosic-substrate-for-ethanol uses?" and, if so, "How can this best be done with DNA markers?" The benchmark genetic information generated in this research can then be applied in breeding for new corn varieties that meet both traditional and bioenergy needs in a sustainable, non-competing way.
OBJECTIVES: Our objective in this research is 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. Specifically, we will (1) determine the prospects of and identify challenges in marker-assisted breeding for both corn grain yield and stover quality traits important for ethanol production, and (2) determine if genome-wide selection (which does not require finding markers with significant effects) is superior to the usual approach of selecting only for significant markers, with the goal of simultaneously improving corn grain yield and stover quality.
APPROACH: We will use simple-sequence repeat DNA 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 intermated B73 x Mo17 corn mapping population. We will determine if there are antagonistic relationships that impede the joint improvement of these traits at the DNA-marker and quantitative-trait level. We will identify which of several stover-quality traits (glucose release, cell-wall glucose concentration, and cell-wall lignin concentration) would be the easiest target for marker-based selection. Furthermore, we will evaluate a novel strategy called genome-wide selection to simultaneously breed for grain yield, agronomic traits, and stover-quality traits. Genome-wide selection, a seemingly counterintuitive procedure that circumvents the need to first identify DNA markers associated with the target traits, has been shown in previous studies to substantially increase the gains from marker-based selection. At the same time, we will determine if there are genomic regions with major effects for glucose release, glucose concentration, lignin concentration, and other cell wall traits.
Name: R. Bernardo