Genetic Mechanisms Regulating Inflorescence Architecture in Maize and other Cereals

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Sarah Hake, University of California, Berkeley, P.I.David Jackson, Cold Spring Harbor, Co-P.I.Elizabeth Kellogg, University of Missouri, St. Louis, Co-P.I.Torbert Rocheford, University of Illinois, Champaign, Co-P.I.Robert Schmidt, University of California, San Diego, Co-P.I.Erik Vollbrecht, Iowa State University, Co-P.I.Volker Brendel, Iowa State University, Senior PersonnelRichard Johnson, University of Illinois, CooperatorThe overall goals of this project is to uncover the network of genetic interactions responsible for maize inflorescence development. A longterm goal is to understand the genetic basis for diversification in inflorescence morphology in grasses, a group of about 10,000 plant species including major cereal crops. The inflorescence is a flowering structure and hold seeds (grains in case of cereals). The variation in architecture of plant inflorescences is largely determined by the activity of meristems, small groups of stem cells that perpetuate themselves and give rise to organs. The diversity among grass inflorescences is particularly striking and results from variation in the identity and determinacy of several distinct meristems produced throughout inflorescence development. This diversity has important agricultural implications as pollen and seeds are produced on branches of the inflorescence. In their previous grant, the investigators cloned a number of key genes that regulate critical steps in the pathway of inflorescence development, from meristem initiation and organization to patterns of branching and meristem determinacy. The specific objective of the current project is to determine how these genes fit into a larger genetic network and to determine divergence and conservation of networks in maize and other grasses. The project takes advantage of new high resolution maize mapping resources and the expected genome sequence to fine map quantitative trait loci (QTL) and use association analysis to link genotype with phenotype. The research will address questions such as why the maize ear and tassel are so distinct yet arise from similar primordia, what are the genes that differentiate diverse branching structures of the grasses, and how variation in inflorescence architecture genes regulates the diverse architectures of maize inbred lines. Answers to these questions will establish a foundation for genetic studies of reproductive biology in cereals and other grass species. In this project, key genes and gene networks that integrate the early steps in ear and tassel development will be identified and those that underlie their distinct phenotypes will be uncovered. These will serve as tools for research in developmental biology, evolutionary biology, applied genetics and breeding, with obvious relevance to maize hybrid seed production and crop improvement. The summer outreach program aims to reach a large number of high school students and undergraduates and provide hands-on experience in field and laboratory genetics and genomics.Access to project outcomesThe mutants to be identified will be in defined inbred backgrounds and will be made available through the Maize Genetics Stock Center (http://maizecoop.cropsci.uiuc.edu/). Project data will be made available through MaizeGDB (http://www.maizegdb.org/).