Posted on Dec 01, 2009
The proposal focuses on the development of an Annotated Individually-pedigreed Mutagenized Sorghum (AIMS) library consisting of 6,400 independent mutant families. With the sorghum genome sequence completed, the challenge is now to harness the genome sequence information to accelerate sorghum improvement for new uses. Mutants are a very powerful tool for relating sorghum (and other) genes to their functions – the visual effects of disrupting a gene quickly inform us about what the gene does in its normal state. One of the major obstacles for sorghum genomic studies is the lack of a systematic mutant population to investigate the functions of sorghum genes and for selection of traits that can be directly used to improve sorghum for new uses, such as foods, feed, health, and bioenergy. As a crop with highly-productive C4 photosynthesis, as well as excellent tolerance to high temperature, drought, and low soil fertility, sorghum is likely to become increasingly important in the future. Expansion into new markets through adaptation of sorghum to new uses is needed to sustain growth and profitability. To fulfill the need for functional genomic studies toward developing sorghum for new uses, we propose to establish a mutant library in the inbred line BTx623. This inbred line was used for the genome sequence, and therefore offers an advantage because mutations can be easily determined through comparison with the reference sequence. BTx623 seeds will be mutagenized by the chemical ethyl methane sulfonate (EMS), which is known to induce a broad spectrum of mutations. The mutagenized seeds will be propagated to the third generation (M3) through single-seed-descent to guarantee that each mutant family is derived from an independent mutation event. Seeds will be bulked thereafter for public distribution. Phenotypes will be carefully evaluated at M3 generation. The mutant plots will be open to public and private sorghum researchers through field days and individual arrangements to select mutants for their respective needs and priorities. All phenotype information will be captured in an online searchable database to benefit sorghum research and foster collaborations. Genomic DNA from each plant that is used to produce the M3 seeds for the mutant library will be prepared. The DNA will be deposited in a central lab for identification of mutants for specific sorghum genes that can serve as potential candidates for sorghum improvement. Coupled with high throughput mutation detection in specific genes, mutagenesis has been used to breed soybean and peanut with high quality oil and low allergenic activity, and to produce high digestible starch in wheat and maize. Our pilot project displayed many potential useful mutations, such as brown midrib mutants, monoculm, large panicle, staygreen, and cold tolerance. Availability of a mutant library with an adequate number of families will accelerate sorghum functional genomic studies and aid the breeding efforts to adapt sorghum into new uses.