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Comparative Chloroplast Genomics

dePamphilis, Claude W. [1], McNeal, Joel R. [2], Zhang, Yan [3], Cui, Liying [1], Kuehl, Jennifer V. [4], Boore, Jeffrey L. [4].

Plastid Genomes of Parasitic Plants: Distinct paths of evolution in independent heterotrophic lineages.

The sequenced plastid genomes of photosynthetic land plants have maintained a near constancy of gene content through hundreds of millions of years of evolutionary divergence. Parasitic and mycotrophic plants, many having lost photosynthetic ability, are valuable tools for understanding the forces that result in such apparent stability. The sequenced plastid genome of one parasite, Epifagus virginiana, has numerous deletions that have removed all photosynthetic and ndh genes, and a surprising set of plastid encoded genes for transcription and translation. It is unknown how general this outcome may be, and whether independent heterotrophic lineages convergently achieve a similar structure. We have sequenced the plastid genomes from four additional parasitic angiosperms that represent three independent lineages of heterotrophic plants: Conopholis americana (Orobanchaceae, as is Epifagus), Pholisma arenarium (Lennoaceae), and Cuscuta obtusiflora.and Cuscuta exaltata (Convolvulaceae). The gene content of Pholisma is strikingly similar to that of both Epifagus and Conopholis, suggesting almost complete convergence, except that a potentially functional rbcL gene has been retained only in Pholisma. Surprisingly, although the third heterotrophic lineage, Cuscuta, has undergone extensive gene loss, both species retain a nearly complete, and highly conserved set of photosynthetic protein genes. These observations have broad implications for chloroplast biology and gene function, mechanisms of genome evolution, and chloroplast phylogenetics.


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Related Links:
Chloroplast Genome Database
Chloroplast Genome Project


1 - Pennsylvania State University, Department of Biology and Institute of Molecular Evolutionary Genetics, University Park, Pennsylvania, 16801, USA
2 - Arnold Arboretum at Harvard University, Cambridge, Massachusetts, 02138, USA
3 - Pennsylvanian State University, Department of Biology, University Park, Pennsylvania, 16802, USA
4 - DOE Joint Genome Institute, Department of Evolutionary Genomics, 2800 Mitchell Drive, Walnut Creek, California, 94598, USA

Keywords:
Chloroplast genome
Parasitic plants
Orobanchaceae
Lennoaceae
Cuscuta
Genome evolution.

Presentation Type: Symposium or Colloquium Presentation
Session: 19-5
Location: Salon K - Austin Grand Ballroom/Hilton
Date: Monday, August 15th, 2005
Time: 4:30 PM
Abstract ID:468


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