Nucleotide distribution in gymnosperm nuclear sequences suggests a model for GC-content change in land-plant nuclear genomes |
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Authors: | S Jansson G Meyer-Gauen R Cerff W Martin |
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Institution: | (1) Department of Plant Physiology, Ume», Sweden;(2) Institut für Genetik, Technische Universität Braunschweig, Spielmannstr. 7, D-38023 Braunschweig, Germany |
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Abstract: | Nuclear protein coding sequences from gymnosperms are currently scarce. We have determined 4 kb of nuclear protein coding sequences from gymnosperms and have collected and analyzed >60 kb of nuclear sequences from gymnosperms and nonspermatophytes in order to better understand processes influencing genome evolution in plants. We show that conifers possess both biased and nonbiased genes with respect to GC content, as found in monocots, suggesting that the common ancestor of conifers and monocots may have possessed both biased and nonbiased genes. The lack of biased genes in dicots is suggested to be a derived character for this lineage. We present a simple but speculative model of land-plant genome evolution which considers changes in GC bias and CpG frequency, respectively, as independent processes and which can account for several puzzling aspects of observed nucleotide frequencies in plant genes.Abbreviations GC
guanosine plus cytosine
- GapC
glycolytic glyceraldehyde-3-phosphate dehydrogenase, EC 1.2.1.12
- GapA
Calvin cycle glyceraldehyde-3-phosphate dehydrogenase, EC 1.2.1.13
- O/E
ratio of observed-to-expected dinucleotide frequencies
Correspondence to: W. Martin |
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