Sorghum is an attractive biomass crop for ethanol production because of its low water and fertilizer requirements, tolerance to heat and drought, high biomass yield, and great genetic diversity. Sweet sorghums are tall sorghums that accumulate soluble sugars in their stems. After squeezing the stalks, these sugars can be fermented directly. The genetic basis for sugar accumulation is poorly understood and hampers the genetic improvement of sweet sorghum. We are employing high-throughput expression profiling using the Solexa platform to identify the gene(s) underlying a recently mapped quantitative trait locus (QTL) for stem sugar concentration. In addition, we are mapping QTL for juice volume, which, combined with sugar concentration, determines sugar yield. Another trait of interest is the brown midrib (bmr) trait. The bmr mutations change the color and the chemical composition of the vascular tissue, which tends to result in improved yields of fermentable sugars after enzymatic saccharification of lignocellulosic biomass. Recent allelism crosses have revealed a number of bmr mutants in a sorghum TILLING population that represent novel loci; these mutants are currently being evaluated for biomass conversion. Combination of these two traits results in brown midrib sweet sorghums that provide fermentable sugars from the juice and, in anticipation of second-generation ethanol plants, from the bagasse.  In the meantime the bagasse can be used as high-energy forage.  Funding from the US Department of Energy for this project (DE-FG02-07ER64458) is gratefully acknowledged.