Monday, November 13, 2006 - 1:30 PM

Genetic Enhancement of Sorghum for Biomass Conversion.

Ana Saballos Espinal, Purdue Univ, Dept of Agronomy, 915 W. State St, West Lafayette, IN 47907, Wilfred Vermerris, Univ of Florida, UF Genetics Institute & Agronomy Dept., P. O. Box 103610, Gainesville, FL 32610-3610, and Gebisa Ejeta, Purdue Univ, Agronomy Dept, 915 W State St, West Lafayette, IN 47907-2054.

Genetic improvement of biomass crops can significantly reduce the overall cost of biomass-to-ethanol conversion. Major traits affecting biomass utility are lignin content and composition, soluble carbohydrate content and overall biomass yield. Sorghum offers inherent advantages that make it an attractive biomass crop. It is tolerant to drought, performs well on marginal lands, and possesses a deep root system that helps prevent the loss of soil organic matter. We are working towards improving the quality of sorghum as a feedstock by combining traits from useful germplasm sources of brown midrib (bmr) lignin mutants, sweet sorghums, stay-green, and high biomass producers. Unfortunately, the genetic basis of these characteristics is poorly understood. In order to elucidate the genetic basis and enhance the efficiency of combining these traits, we have developed a population of recombinant inbred lines from crosses between a sweet sorghum and a bmr mutant.  Characterization of this population will allow identification of loci associated with biomass yield, cell wall composition and soluble sugar content in the phloem.  Through a combination of genetic and chemical approaches we have also established the specific number of independent bmr loci associated with our collection of bmr mutants.  Furthermore, we have successfully implemented a candidate-gene approach to characterize the bmr6 mutation, based on the chemical composition of the mutants’ cell wall and mapping data.  A combination of classical breeding and marker assisted selection is being used to develop improved lines for biofuel production. This research is also contributing valuable genetic tools to breeding programs for forage sorghums with enhanced feed quality.