With these duplications and reductions, genes in chromosome segments can be lost, replicated or shifted over to other chromosomes, Messing explained. As a consequence, plant genomes today contain rearranged segments and many duplicated regions with corresponding sets of genes. In the maize genome, genes were apparently lost in some parts and new "stuffer" pieces (intervals between genes) inserted so that the corresponding segments became different in size.
The researchers found that about 10 percent of the genes in the maize segments were missing completely in rice, and about 20 percent were in new positions. Within the maize segments, genes appear to be very mobile: 20 to 25 percent have "jumped" to other locations in the genome during the course of evolution. Two-thirds of the original genes from the ancestral four sets of chromosomes have disappeared completely. Corresponding genes wound up in completely different locations within the genome and have likely undergone changes in how they affect biological operations.
"The research, conducted by an international collaboration of scientists, will help scientists and farmers improve these significant crops and gain new and important insights in the evolution of the grass species in general," Messing said.
"The vast pool of genetic material in plants can be an important resource from which biotechnology can draw genes for insertion into an array of plants, generating unique genomes not achievable by conventional breeding," Messing said. "We could engineer plants to provide a more sustainable, healthy and productive source of food, while reducing the environmental impacts of their cultivation."