The overall goal of the project is to determine the structure, composition and evolution of several important plant genomes: barley, maize, rice, sorghum and wheat. The chromosomes of plants are very large and complex in structure, although different plant species vary by over 500 fold in the amount of DNA contained within the chromosomes. Despite this tremendous variation in DNA amount, gene content appears to vary relatively little. Hence, it would be valuable to determine the nature of the DNA content in the chromosomes of plants, and how these DNAs (especially genes) are arranged. The family of plants called grasses, including barley, maize, rice, sorghum and wheat, provide most of the world's food and are also fairly closely related. Yet they differ over 11 fold in genome size and have very different optimal growth environments and yield potential. This study will investigate the composition of sequences in four to five evolutionarily-related regions of these five genomes. The approach will be to generate the DNA sequence of approximately 100 kilobase pair segments for each genome, isolated as clones in bacterial artificial chromosome vectors. These sequences will then be analyzed for gene content and organization, and for the presence and nature of other types of DNAs. These results will indicate how grass chromosomes are composed and how they evolve. This knowledge will permit more efficient techniques in all laboratories for gene isolation, for gene study, and for genetic engineering.
