|Jansen, Constantin -|
|DE Leon, Natalia -|
|Hirsch, Candice -|
|Ruff, Leah -|
|Luebberstedt, Thomas -|
Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 19, 2012
Publication Date: March 17, 2013
Citation: Jansen, C., De Leon, N., Lauter, N.C., Hirsch, C., Ruff, L., Luebberstedt, T. 2013. Genetic and morphometric analysis of cob architecture and biomass related traits in the intermated B73xMo17 recombinant inbred lines of maize. BioEnergy Research. 6(3):903-916. Interpretive Summary: Cob biomass is a widely abundant residual in the U.S. Corn Belt, and has received increased interest for generating renewable energy. New cob harvest and conversion technologies are available and cob biomass is considered for combustion or gasification in power plants and cellulosic ethanol production. While grain usage for energy competes with food production on limited acreage, cobs can be harvested in addition to grain. Therefore, cobs do not require additional acreage, such as short rotation poplar or miscanthus. If stover remains in the field, harvest of cobs with nitrogen content below 1% will hardly affect soil fertility or significantly change fertilizer management. In order to further optimize economic feasibility of cob utilization, a denser cob biomass tissue will make harvest and transportation more efficient. Even though maize is among the best investigated crops, little is known about the genetic basis of cob biomass properties, defined by cob volume, density, and biomass quality. Here we report a detailed morphometric characterization of cob biomass traits in relation to one another as well as in relation to general plant architecture traits. In addition, we report the genomic locations and strengths of action for more than 50 genetic factors that improve cob biomass traits, providing genetic evidence that these traits are amenable to agronomic improvement. Breeding strategies that apply these new results are discussed in the paper as well.
Technical Abstract: Expected future cellulosic ethanol production increases the demand for biomass in the U.S. Corn Belt. With low nutritious value, low nitrogen content, and compact biomass, maize cobs can provide a significant amount of cellulosic materials. The value of maize cobs depends on cob architecture, chemical composition, and their relation to grain yield as primary trait. Eight traits including cob volume, fractional diameters, length, weight, tissue density, and grain yield have been analyzed in this quantitative trait locus (QTL) mapping experiment to evaluate their inheritance and inter-relations. 184 recombinant inbred lines of the intermated B73xMo17 (IBM) Syn 4 population were evaluated from an experiment carried out at 3 locations and analyzed using genotypic information of 1339 public SNP markers. QTL detection was performed using i) comparison wise-thresholds with reselection of cofactors (a= 0.001), and ii) empirical LOD score thresholds (P=0.05). Several QTL with small genetic effects (R² = 3.2 – 15.6%) were found, suggesting a complex quantitative inheritance of all traits. Increased cob tissue density was found to add value to the residual without a commensurate negative impact on grain yield and therefore enables for simultaneous selection for cob biomass and grain yield.