Engaging the Sorghum Genome Sequence - Mississippi Genome Exploration Laboratory - MGEL - Daniel G. Peterson - Genomics, Cytogenetics, Molecular Genetics

ENGAGING THE SORGHUM GENOME SEQUENCE

Sorghum bicolor (grain sorghum) is a staple food for millions of people in the semi-arid tropics (in particular Africa and India) and is an important feed crop in the U.S. S. bicolor is similar to maize in nutritional content, but it is higher in protein and lower in fat content. Of cereals grown in the U.S., grain sorghum is fourth in economic value. Its resistance to heat and water stress allow it to be grown in regions where other grain crops cannot compete. With growing demands on fresh water supplies and the probability of continued global warming, it is likely that the relative importance of S. bicolor will increase.

Sorghum bicolor, a relatively small-genome species, is closely related to important large-genome tropical grasses such as maize and sugarcane (all three are in the tribe Andropogoneae), and consequently sorghum affords a better 'gateway' into these genomes than rice (tribe Oryzeae), a temperate grass species. Unlike temperate grasses, sorghum and most other tropical grasses have 'C4 photosynthesis' allowing them to more efficiently assimilate carbon during times of heat stress.

The genus Sorghum contains not only S. bicolor, but also several other species including S. halepense, an extremely aggressive weed. Commonly known as johnsongrass, S. halepense is a polyploid hybrid of S. bicolor and the wild species S. propinquum. Johnsongrass can reduce yields of maize, soybean, cotton, etc. up to 45% by directly competing with the crop plants for resources and by serving as a reservoir for insects and pathogens. Genome research on the different Sorghum species (S. bicolor, S. propinquum, and S. halepense) will likely produce information beneficial to those interested in crop improvement and those interested in control of detrimental weeds.

MGEL's Sorghum Research

Since its inception in 2002, MGEL has been involved in research on the genome of Sorghum bicolor. MGEL has led cytomolecular mapping and CBCS research on sorghum as part of the Comparative Grass Genomics Center (CGGC), an NSF Plant Genome "Virtual Center" led by Andrew H. Paterson (U of GA). While the CGGC award expired in 2005, many aspects of the research are still in progress.

In 2005, a group of scientists led by Paterson and including MGEL's Daniel G. Peterson submitted a Community Sequencing Proposal to the Department of Energy's Joint Genome Institute (JGI) requesting that the JGI sequence the entire Sorghum bicolor genome (8X coverage). The proposal was successful, and sorghum genome sequencing is nearing completion. Of note, MGEL provided all of the sorghum DNA (cultivar BTx623) used in sequencing. MGEL is currently participating in sequence analysis and annotation of the sorghum sequence. Additionally, MGEL is integrating the sequence with the cytomolecular map (generated as part of their CGGC research) to construct a "cytophysical map" of the sorghum genome.

Refereed Publications or Book Chapters (to date) with MGEL Personnel as Authors

Draye et al. 2001, Peterson et al. 2002, Paterson et al. 2003, Paterson et al. 2004, and Peterson 2005.