Emerging Model Species for Developmental, Evolutionary and Functional Analyses
Malcomber, Simon , Christensen, Ashley , McSteen, Paula , Jackson, David .
The developmental genetic basis of inflorescence diversity in grasses (Poaceae).
The grass family (Poaceae) comprises approximately 10,000 species and includes the cereal crops that provide the bulk of human caloric intake. Grasses are commonly differentiated based on the shape and sizes of floral organs, how many flowers are collected into spikelets, and the amount of inflorescence branching. Most data on the genes regulating these features are derived from the model species corn and rice. Combining functional data in these model species with estimated phylogenetic relationships within the family provides an extensive list of genes that likely contributed to the diversity of grass inflorescence morphology and an evolutionary framework of where patterns of gene expression or function are expected to have changed. Our evolutionary analyses of this diverse set of developmental genes in grasses and immediate relatives have recovered a complex pattern of gene duplication and loss, coupled with functional conservation and diversification. Based on analyses in phylogenetically disparate grasses BARREN INFLORESCENCE2, a serine threonine kinase co-orthologous to Arabidopsis PINOID (PID), is hypothesized to regulate axillary meristem initiation in all aspects of inflorescence, spikelet and floral development in diverse grasses. In contrast, genes within the monocot-specific trehalose phosphate phosphatase (TPP) RAMOSA3/SISTER OF RAMOSA3 (RA3/SRA) clade have divergent roles. RA3 and SRA were produced from a duplication event near the base of the major diversification of grasses. RA3 regulates inflorescence development in corn, but has yet to be isolated from non-panicoid species and has been lost in rice. SRA is present throughout grasses and regulates inflorescence branching in inland sea oats, rice and sorghum, but has a generalized role in corn. These examples and others demonstrate the utility of combining developmental and evolutionary analyses to test hypotheses from model species that, in turn, provide new hypotheses on the complexity of mechanisms regulating morphological form.
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1 - California State University - Long Beach, Biological Sciences, 1250 Bellflower Blvd, Long Beach, California, 90840, USA
2 - California State University - Long Beach, Biological Sciences, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA
3 - The Pennsylvania State University, Biology, 607 Mueller Lab, University Park, PA, 16802, USA
4 - Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York, 11724, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 1/Hilton
Date: Monday, July 9th, 2007
Time: 2:00 PM