© 2002-2005
CSGR The University of Georgia
© 2002-2005
CSGR The University of Georgia
“Why Sorghum?” you ask –- “Because it is so important!”
Sorghum (Sorghum spp.), is one of the world’s leading grain crops, and an important model for tropical grasses of worldwide importance with a minimum economic impact of US $69 billion per year. Sorghum provides food, feed, fiber, fuel, and chemical feedstocks across a range of environments and production systems. Worldwide, sorghum is the 5th most important grain crop grown based on tonnage (http://www.fao.org). It is second only to maize as a US fuel ethanol crops, and is very closely related to sugarcane, the world’s most important biofuels crop.
The remarkable ability of sorghum to produce a crop under adverse conditions, in particular with much less water than most other grain crops, makes it an important ‘failsafe’ in the global agroecosystem. Increased demand for limited fresh water supplies, coupled with global climatic trends, and expanding populations, suggests that dryland crops such as sorghum will be of growing importance.
The Sorghum genus is also noteworthy in that it includes one of the world’s most noxious weeds, ‘Johnson grass’ (S. halepense). The rapid dispersal, high growth rate, and durability that make Johnson grass such a troublesome weed are actually desirable in many forage, turf, and biomass crops which are genetically-complex. Therefore, sorghum offers novel learning opportunities relevant to weed biology as well as to improvement of a wide range of other forage, turf, and biomass crops.
As a model organism for tropical grasses, sorghum is a logical complement to the temperate grass Oryza (rice), the first monocot plant to be sequenced. Sorghum is more closely related than rice to major crops of tropical origin such as maize, sugarcane, and pearl millet, and thus provides a better roadmap for study of these crops at the DNA level. Sorghum is representative of the tropical grasses in that it has ‘C4’ photosynthesis, with biochemical and morphological specializations that result in more efficient carbon assimilation at high temperatures. By contrast, rice is representative of temperate grasses, using ‘C3’ photosynthesis.
Extensive anchoring of the sorghum maps to those of rice, maize, sugarcane, millet, banana, Bermuda grass, switchgrass, and other monocots provides for the cross-utilization of results to advance knowledge of many important crops. While maize and sugarcane are similar in size to the human genome, the sorghum genome is 75% smaller, and enjoys a detailed genetic map, genetically-anchored sequence-ready physical map and many other tools and information.
Unique learning opportunities can be derived from Sorghum research. We have built extensive genomic resources not only for cultivated sorghum, but also for a wild relative, S. propinquum, which differs from the cultivated species by an average of only 1.2% in the DNA sequences (spelling) of genes. This offers an important opportunity to learn about the changes that occurred during ‘domestication’ of wild plants by humans.
It is also noteworthy that S. halepense or “Johnson grass”, one of the worlds most noxious weeds, resulted from hybridization of S. bicolor and S. propinquum. Genetic analysis of S. propinquum offers novel learning opportunities about weed biology as well as improvement of a wide range of other forage, turf, and biomass crops.
Sorghum research benefits many stakeholders. Representatives of both US (National Grain Sorghum Producers, Comparative Cereal Genomics Initiative) and international (ICRISAT, CGIAR Challenge Program, Rockefeller Foundation) organizations attest to the high value of sorghum research.
Sorghum is an important failsafe crop in both the US and the global agroecosystem, making a crop even in drought years when maize and other grains fail. Internationally, sorghum research provides intrinsic low-cost genetic solutions to problems facing large populations that depend upon sorghum and related tropical grasses for subsistence. For example, in the more arid countries of northeast Africa, such as Sudan, sorghum contributes 39% of the calories in the human diet (http://www.fao.org, 1999 statistics).
Sorghum is an important botanical model for research in many other plants. The international sugarcane research community makes heavy use of sorghum genomic tools and has invested substantially in their development. Finally, the US turf and forage grass research community also uses sorghum as a key model.
Our goals. Despite the likely growing importance of sorghum, its improvement has lagged that of maize, wheat and rice, each of which have more than doubled in average yield on a worldwide basis in the last 38 years while sorghum yields have only gained 51% (average 1961-1963 compared to 1999-2001 – http://www.fao.org). Our goals are to empower accelerated improvement of sorghum by increasing knowledge of its intrinsic genetic potential and utilizing that knowledge toward realizing greater productivity and quality in manner that is consistent with responsible environmental stewardship. Due to the many faces of sorghum (crop, weed, and botanical model), this will also yield many fringe benefits, increasing knowledge of biological diversity and plant growth and development.
For more information about sorghum and its importance in the USA, please click here
For more general information about US sorghum production and utilization, please click here
