Plant development and evolution: Lessons learned from candidate genes
Zanis, Michael , Schmidt, Robert , Kellogg, Elizabeth .
The dynamics of gene duplication in grasses.
We are interested in the role of gene duplication in the evolution of pathways controlling floral organ development. We are examining the grass MADS-box genes ZAG1 and ZMM2, members of the “C class” clade of MADS-box genes. ZAG1 and ZMM2 are developmentally important duplicate genes that appear to be key determinants of stamen and carpel specification in grasses. In maize, ZAG1/ZMM2 appear to have partitioned function through the evolution of sub-functionalized coding and non-coding cis-regulatory regions. Using phylogenetic methods, we have identified the origin of the ZAG1/ZMM2 duplication in grasses, and we have characterized the expression patterns of ZAG1 and ZMM2 in specific grass taxa and in non-grass species that diverged prior to the ZAG1 and ZMM2 duplication. Our data indicates that the duplication occurred just prior to the diversification of the grasses, with closely related non-grass lineages having only a single ZAG1/ZMM2 gene. Both genes appear to have been preserved in all of the grass lineages, suggesting selection for retention of both gene activities early in the history of this duplication event. Our gene expression data, in situ hybridizations and RT-PCR analyses, suggest that taxa closely related to the grasses that have only a single copy of ZAG1/ZMM2 show gene expression in both stamens and carpels. Among the grasses, ZMM2 is expressed in both male and female organs throughout development, whereas ZAG1 is expressed in both organs early in development but in later development is restricted to the carpel. We will also present functional studies using Arabidopsis to uncover differences in ZAG1/ZMM2 C-function, and data on the duplicate genes ZMM25 and ZAG2/ZMM1, “D class” MADS-box genes, which may play an important role regulating carpel/ovule development. Lastly, we will tie our results into those from Arabidopsis and discuss the complexity of incorporating gene duplications into general models of organ development.
1 - Universtiy of California -- San Diego, Division of Biology, Section of Cell and Developme, 9500 Gilman Drive, La Jolla, California, 92093-0116, USA
2 - University of Missouri-St. Louis, Biology, 8001 Natural Bridge Road, St. Louis, Missouri, 631321, USA
Presentation Type: Symposium
Location: Ballroom 1 (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 3:15 PM