5-11: In search of genetic determinants of a bioenergy sorghum ideotype

 

Because of its low water and fertilizer requirements, tolerance to heat and drought, high biomass yield, and great genetic diversity, sorghum is a very attractive crop for ethanol production from grain, soluble sugars and biomass. Environmental stresses can, however, severely reduce its yield potential. Drought stress is one of the major constraints on crop production, and is expected to increase in the future as a result of climate change. Although sorghum as a species is very drought tolerant, considerable variation in this trait can be observed among genotypes, and can be explained in part by differences in root system architecture. Anthracnose, caused by the pathogen Colletotrichum sublineolum, affects the quantity and quality of the biomass. Tolerance to anthracnose is of paramount importance for sorghum production in humid areas. We are working towards the identification of quantitative trait loci that govern root traits and anthracnose resistance. This will facilitate the introgression of desirable traits into high-yielding lines. Biomass composition also impacts the final ethanol yield of the crop. We have shown that the yield of fermentable sugars from biomass is affected by lignin content and composition and have previously identified and characterized genes underlying two brown midrib (bmr) mutations. The genomic location of a third bmr locus has recently been identified and we are using a map-based cloning approach to identify the underlying gene. The combination of QTL identification and mutant characterization followed by gene expression studies will allow us to identify genes underlying traits for successful bioenergy production.