McNeal, Joel R. , Kuehl, Jennifer V. , Boore, Jeffrey L. , dePamphilis, Claude W. .
Evolution of matK, a conserved plastid intron maturase, in the parasitic plant genus Cuscuta.
PLASTID genome content and arrangement are highly conserved across most land plants and their closest relatives in the algal order Charales. Almost all plastid introns appeared prior to the divergence of these two lineages; one such intron within the transfer RNA trnK-UUU contains a large open reading frame that encodes a presumed intron maturase, matK. Although this gene is found in all published land plant and Charophyte plastid genomes, including that of the nonphotosynthetic angiosperm Epifagus virginiana (Orobanchaceae), its exact function is still not fully known. The parasitic angiosperm genus Cuscuta (Convolvulaceae) is highly heterogeneous in plastid intron content and serves as a good candidate for studying the intron-splicing function and specificity of matK. We examined intron evolution and distribution in Cuscuta along with corresponding evolutionary changes in matK. Loss of many group II introns from the plastid genome results in substantial change in selective pressure within the hypothetical RNA-binding region (domain X) of matK in both Cuscuta and Epifagus. The intron-splicing function of matK is likely limited to group IIA introns in Cuscuta, corroborating previous circumstantial evidence from cereal crops.
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1 - Harvard University, Arnold Arboretum, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
2 - DOE Joint Genome Institute, Department of Evolutionary Genomics, 2800 Mitchell Drive, Walnut Creek, California, 94598, USA
3 - Pennsylvania State University, Department of Biology and Institute of Molecular Evolutionary Genetics, University Park, Pennsylvania, 16801, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 8:45 AM