Thursday, May 3, 2012: 10:00 AM
Waterbury Ballroom, 2nd fl (Sheraton New Orleans)
Sweet sorghum (Sorghum bicolor (L.) Moench) is a tall, annual, seed-propagated grass that accumulates soluble sugars in its stem. It is an attractive bioenergy crop because the sugars can be easily extracted from the stem and directly converted to fuels and chemicals by microorganisms. The bagasse that remains can subsequently be used as a lignocellulosic feedstock. Genetic improvement of sweet sorghum is focused on increasing sugar and biomass yields, pest and disease resistance, and efficient uptake and use of water, but the lack of understanding of the genetic basis of sugar accumulation is currently a limiting factor. A major quantitative trait locus (QTL) for stem sugar concentration was identified on chromosome 3 based on the analysis of a recombinant inbred line population derived from the sweet sorghum ‘Rio’ and the grain sorghum BTx623. To identify the gene(s) underlying this QTL, expression profiling using the Illumina HiSeq platform was conducted on the progeny of an F5 individual heterozygous for the QTL. Stem and leaf tissue collected at two developmental stages from progeny contrasting for the QTL alleles resulted in 16 libraries that were multiplexed and sequenced. A total of 481 million reads were obtained, 74% of which aligned to the sorghum transcriptome. Expression profiling reduced the number of candidate genes within the QTL from 216 to just 17. The presence of several regulatory genes among them, and the differential expression of a number of sugar-related genes outside the QTL provide new clues on the genetics of sugar accumulation. Supported by DOE grant DE-FG02-07ER64458.