The Genetic Basis of Morphological Differences Between Two Species of Setaria (Poaceae)

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Foxtail millet is a minor grain consumed by people in some parts of Asia, and is thus of potential value to Third-World agriculture. This project studies the genome of foxtail millet to determine how similar it is to its relative corn, and also to determine similarities to wild grasses. A genome map will be developed by studying the offspring of crosses between foxtail millet and its wild ancestor, green millet. One such cross hasalready been done by scientists at the John Innes Centre (JIC) in Norwich, England; they have used genes from millet and from rice to determine the structure of the millet genome. Using their plant material, several regions of the millet genome were identified that control the size and shape of the seed head, which influences the amount of grain produced. The specific goals in this project are to: 1. Locate genes from corn in the plants from the JIC. This will allow determination of which corn genes also function in millet, based on map position. 2. Place developmentally important genes on the JIC map to determine if they map to any of the regions known to affect the structure of the seed head. If they map to the same region, it will not prove that they control seed head development, but if they map elsewhere, then they can be excluded as candidates. 3. Make another cross between the two millet species to create a second, larger set of plants, to replicate the experiment. 4. Begin development of near-isogenic lines from our plants and the JIC plants, to verify the results of the mapping studies. The characterstics that distinguish green millet and foxtail millet are not unusual for grass species. They are mostly quantitative changes in the relatives sizes and numbers of parts, the sorts of changes that distinguish most species of grasses. This study will thus help understand the genes in foxtail millet, but will also provide a glimpse of the genetic basis of plant diversity.