Scientists Decode Sorghum Genome

An international team of researchers have deciphered the genetic blueprint of sorghum, a hardy crop and important food, fodder and biofuel source. Scientists believe that the breakthrough could eventually lead to the development of drought-resistant crops for arid regions with rapidly burgeoning population, such as West Africa. Sorghum is the second grass to have its genome sequenced, after rice. The comparative analysis of the sorghum genome appears in the recent issue of the journal Nature.

Sorghum (Sorghum bicolor), a close relative of sugarcane, originates from tropical Africa where it is a staple food and is now grown in dry areas in the U.S. and India. Worldwide production of sorghum is estimated at 60 million tons annually. The researchers used the whole genome “shotgun” method of sequencing, wherein short random DNA stretches are partially sequenced and then analyzed by a supercomputer to reconstruct the original genome sequence. The technique was first pioneered in the Human Genome Project.

 With approximately 730 million nucleotides and 30,000 genes, the crop’s genome is 75 percent larger than the size of rice. Comparisons of the genome with rice shed light on the evolution of grasses and of C4 photosynthesis, a carbon fixation pathway found in plants growing in conditions of high temperature and light intensity and low water availability. The scientists also found evidences that recent gene and microRNA duplications contributed to sorghum's drought tolerance. For instance, the rice miRNA 169g, upregulated during drought stress, has five sorghum homologs.

Subscribers to Nature can read the full article at http://dx.doi.org/10.1038/nature07723 For more information, read http://www.nature.com/nature/journal/v457/n7229/full/nature07723.html and http://www.jgi.doe.gov/News/news_09_01_28.html