Original NSF Proposal
"From the genome to the tree of life"
NSF Proposal Body Bibliography Initial Core Participant's statements
Charles F. Delwiche John Doebley Elizabeth A. Kellogg Brent Mishler Melvin Oliver
Daphne Preuss Yin-Long Qiu Douglas E. & Pamela S. Soltis Chris Somerville S.D. Tanksley
Virginia Walbot Paul G. Wolf Elizabeth A. Zimmer . .

Charles F. Delwiche

University of Maryland - College Park

Current research activities:
The Delwiche lab's research focuses on the reconstruction of early events in the evolution of photosynthetic organisms, with emphasis on the evolutionary origin of embryophytes (land plants) from green algae, and on the endosymbiotic origin of plastids. Current projects are: 1) systematics and taxonomy of charophycean green algae, with current funding from NSF grant DEB-9978117, "PEET: a unified approach to systematics of basal streptophytes (charophycean green algae)", and 2) the molecular biological basis for the incorporation of the peridinin-type dinoflagellate plastid into the host cell, funded in part by a grant from the Alfred P. Sloan Foundation,and in part by NSF grant MCB-9984284, "Plastid-associated genes in dinoflagellates identified by cDNA screening and expression analysis."

The basal streptophytes include five orders of green algae that are very closely related to land plants (embryophytes; Graham, Delwiche et al. 1991). The state of systematic work in each of these orders is different, in large part because of their very different morphologies, and because they were not historically classified together. We are working to develop a uniform classification of these organisms, to develop a definitive phylogeny for the group, and to improve the understanding of their structure and biology. We have determined that some recent studies have been misled by sequencing artifact (Cimino, Karol et al. 2000), and are investigating the influence of methodological issues on the reconstruction of phylogeny within the basal streptophytes. We are also performing molecular phylogentic and morphological studies in each of the orders within the group, and will use these data to develop monographs or addenda to existing monographs, as is appropriate depending upon the current state of taxonomy in each order.

A review of the current state of knowledge concerning the origin and evolution of plastids is presented by Delwiche (Delwiche 1999). In our work on dinoflagellates, we have succeeded in independently isolating several genes that appear to be from the peridinin-type plastid genome, and are currently working to verify their localization to the plastid. In the course of this project we have participated in the identification of tertiary plastids in one group of dinoflagellates (Tengs, Dahlberg et al. 2000), and in the development of molecular methods for the identification of Pfiesteria piscicida (Oldach, Delwiche et al. 2000), and a manuscript discussing the evolution of pigmentation in peridinin-type plastids and other chlorophyll-c containing plastids is currently in preparation. We are now moving into a new phase of this project, in which we will apply genomic methods to investigate the organization of the dinoflagellate plastid genome and the genetic integration of the plastid into the host cell. Because the nuclear genome of most dinoflagellates is exceptionally large (as much as 100 fold larger than the human genome), we are using a cDNA approach to examine genome complexity and expression. One key question is why these organisms have such remarkably large genomes; it is not clear that the complexity of the genome matches its large size. To understand the organization of the dinoflagellate genome, it will also be important to determine whether the genome is polyploid, and the extent to which dinoflagellate genes are encoded as polygenes.

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