Molecules to Morphology: Developing an Understanding of Plant Evolution Through Time
Deboer, Gwynne , Li, Wenli , Kuzoff, Robert K. .
Clarifying the natural history of the class III lineage in the HD-ZIP gene family among land plants.
Functional divergence in gene families is a major force in the evolution of plant form. Research in our lab explores events in the diversification of the class III lineage of the HD-ZIP gene family (HDZ-III) among land plants. We analyzed 72 HD-ZIP sequences sampled from liverworts, bryophytes, lycophytes, spermatophytes, and angiosperms. Surveyed embryophytes generally have one or two HDZ-III genes per species, except in angiosperms, which have as many as six. We used a series of weighted parsimony and Bayesian analyses to assess the phylogenetic structure of the HDZ-III lineage among land plants. The inferred topology for HDZ-III recapitulates land plant phylogeny, with minor exceptions. Lycophytes, liverworts, and bryophytes did not resolve as distinct clades, but, together, form the first diverging branch. The second branch, which received little internal support, includes all gymnosperm HDZ-III. Angiosperm sequences form a large, but poorly supported clade that comprises three sub-lineages; COR, REV, and PHB. These three sub-lineages are moderately to well supported. Within the angiosperms, PHB and REV are sister to one another. After the origin of flowering plants, the gene family underwent an appreciable proliferation as a result of several gene duplication events. Five ancient duplications (~ 91 to 226 MYA) in the gene family propelled its early expansion among flowering plants. Eleven more recent duplications are estimated to have occurred within specific sub-lineages of the angiosperms. Additionally, in situ hybridization results indicate that the functions of the HDZ-III promoters have diverged relative to their counterparts in Arabidopsis.
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1 - University of Wisconsin, Department of Biological Sciences, Whitewater, WI, 53190, USA
2 - Indiana University, Bloomington, IN, 47408, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 5/Hilton
Date: Wednesday, July 11th, 2007
Time: 2:15 PM