Regulation of Inflorescence Architecture in Maize

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

The cereal crops, such as maize, rice, wheat, sorghum, barley, millet, and oats, account for the majority of world's nutrition. In addition to the cereal crops, there are approximately 10,000 species of wild grasses, which cover about 1/5 of the earth's land surface. Nearly all grasses are characterized by the spikelet, a short branch that contains floral meristems. Floral meristems produce the seeds that are harvested. The arrangement of these spikelets in different grasses, and the branches on which they are borne, reflects differing fates of the meristems produced during inflorescence development. Identifying the genes that determine meristem fates and understanding the mechanism by which these genes integrate their activities would be of immense value for developmental biology, evolutionary biology, and applied genetics and breeding. Development of maize as a model system assumes that information from maize should be applicable to other cereals, and indeed to any other plant. Comparisons between maize and the other cereals, and between maize and wild grasses, will test this basic assumption of model system development. Inflorescence genes will be identified that will serve as tools for three different disciplines: investigation of meristem development, quantitative trait analysis, and comparative biology in the grasses. Sequencing of expressed genes and expression profiling will be used to identify a subset of genes that are expressed at the earliest stages of development, and that correlate with the proliferation of specific meristem types in selected mutants. The function of these genes will be determined through genetics and mapping. Map positions of the inflorescence genes will provide a link to quantitative traits, and to mutations in maize and other grasses. A selected group of genes will be mutated by reverse genetics to determine their function in inflorescence development. A subset of the genes will also be studied in other cereals and wild grasses. Whether these genes have been modified over evolutionary time and whether they function in other grasses the same way as they do in maize will be determined. These comparisons will provide a valuable data set for the study of evolution and diversity across 60 million years of grass evolution.