Title: Sorghum Mutant Library as a Genetic Resource to Improve Biomass Yield and BioEnergy Conversion Efficiency Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 25, 2011
Publication Date: N/A
Technical Abstract: Due to the dwindling of mineral energy resources and soaring fuel price, agriculture sector is called to provide bioenergy in addition to the traditional role of providing humanity with food, fiber, and feed. Freshwater is likely a major challenge for developing biofuels because the trend of global warming and rapid decline in freshwater resource. At present, agriculture consumes over 80% of the freshwater, which is unsustainable. Innovative strategies are urgently needed to increase food and feed production to meet the need of the growing world population and to produce bioenergy in a way that should not further erode the already strained natural ecological environment. Sorghum (Sorghum bicolor L. Moench) is a C4 plant with high water use efficiency and is the fifth most important grain crop, providing staple food and fodder for much of the world, especially in arid and semi-arid regions. As a crop with unusual resistance to drought/heat stresses and tolerance to low soil fertility, sorghum has emerged as a promising bioenergy crop. Completion of the sorghum genome sequence has opened many new avenues for sorghum functional genomics and improvement. However, the availability of genetic resources, specifically mutant lines, is limited. Chemical mutagenesis of sorghum germplasm, followed by screening for mutants altered in important agronomic traits, represents a rapid and effective means of addressing this limitation. We have created a sorghum mutant library consisting of 6,400 pedigreed M4 lines through single seed descent from M1 in the elite inbred line BTx623 that was used for sequencing the genome. The mutant library displays a wide range of mutant phenotype in morphological, physiological, and agronomic traits (http://www.lbk.ars.usda.gov/psgd/index-sorghum.aspx). Brown midrib (bmr) mutations is a major trait to improve digestibility and bioenergy conversion efficiency of maize and sorghum stover. A systematic screening of the mutant library identified over 100 bmr mutants, including four new loci that have never been reported before. These bmr mutants can serve as important resource to improve sorghum as biofuel feedstock. We also identified many other mutants, such as erect leaf, monoculm, multi-tiller, large head, early and late flower, etc., which may have potential applications in improving grain and biomass yield and quality. Recently, we have established a high throughput reverse genetic platform to identify mutant series for genes with known sequence through TILLING (targeting induced local lesions in genome), which will be accessible through collaborative research.