Scientists have sequenced the extremely complex genome of the maize plant, one of our oldest and most important crops. This achievement should lead to new insights into plant genetics as well as major progress in breeding crops that are more environmentally sustainable or better-suited for certain climates.
The results appear in a package of articles in the 20 November issue of Science. A set of companion papers also appears in the journal PLoS Genetics this week.
An example of maize diversity. The ears of maize show natural variation in their levels of carotenoids, an organic pigment.
[Image © Science/AAAS]
In the primary Science article, a large research team called the Maize Genome Sequencing Consortium describes the genome sequences of the B73 inbred maize line. B73 is used frequently to breed new lines of feed corn, and its genome sequence should provide genetic markers that could help plant breeders or seed companies develop carefully tailored crops. These crops could have higher nutritional content, for example, or might require less fertilizer. Or, they may better withstand the environmental stresses associated with global climate change.
The genome sequence should also help biologists answer a number of long-standing questions in plant genetics, including the impact of mobile DNA sequences called transposable elements and how the modern maize genome evolved after two ancestral genomes fused together.
The B73 sequence “promises to advance basic research and to facilitate efforts to meet the world's growing needs for food, feed, energy and industrial feed stock in an era of global climate change,” the researchers write.
Other findings reported in this Science issue include:
- Popcorn Reveals Clues to Domestication: The domestication of the teosinte plant into maize may have involved genes that help the plants tolerate metal in the soil, researchers concluded after comparing the B73 genome with that of a type of popcorn grown in the Mexican highlands.
- Genetic Diversity Across Maize Lines: By analyzing 27 different maize lines, another team has developed a maize haplotype map, or “HapMap,” showing common patterns of genetic variation. This map should be a particularly useful tool for teasing apart the genetic basis for agronomically important traits, such as yield, quality and stress tolerance.
- The Male Influence: Gene copies inherited from the male parent control the expression of thousands of other maize genes, a phenomenon known as imprinting. Although the precise connection is not yet clear, according to one of the companion studies, the paternal dominance observed in maize help explain why hybrid maize lines are agriculturally superior to their inbred parents.