Grain by grain, rice feeds more bellies than any other food crop. As a testament to its importance worldwide, scientists from ten countries have teamed up to determine the complete sequence of the rice genome. Now, in the July issue of Genome Research, Rod Wing and colleagues (Clemson University) report good news for the international project: a preview of the genome suggests completion of the sequence may come easier than imagined. In addition, the researchers report findings that should greatly accelerate the search for genes in rice and other cereal plants.
Despite spectacular progress in genome sequencing, scientists have yet to publish the complete sequence of a plant genome. In many plants, a high fraction of the DNA is composed of repeated sequences called transposons, which forms a stumbling block to sequencing projects. As a preliminary step researchers have sequenced over 73,000 DNA fragments distributed over the entire rice genome. Wing and colleagues examined these sequences for the presence of transposons in the rice genome. They discovered that transposons in fact constitute less than 10% of the genome, scattered randomly rather than clustering in lengthy blocks. The discovery is good news for the genome project, suggesting transposons will not greatly interfere with the completion of the rice sequence. Furthermore, the researchers found many examples of a recently described form of transposon called MITE, which often appears in close proximity to genes. Rice MITEs will therefore help researchers locate new genes in rice and probably other important cereals such as corn, wheat, and barley. This preliminary look at the rice genome reveals the enormous promise of the rice project as the first step towards sequencing the globally vital cereal plants.
Contact (author):
Rod Wing
Clemson University Genomics Institute
Clemson, SC 29634
USA
rwing@clemson.edu
Journal
Genome Research