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Plastid DNA from Pyrenomonas salina (Cryptophyceae): physical map, genes, and evolutionary implications
M Maerz1, J Wolters, C J Hofmann
1Institut für Biologie II, Lehrstuhl für Zellbiologie, Freiburg, Federal Republic of Germany.
Current Genetics
|January 1, 1992
Summary
Cryptomonad plastid DNA, originating from red algae symbiosis, was mapped and sequenced. Phylogenetic analysis confirms cryptomonad plastids
Area of Science:
- Algal genomics
- Molecular evolution
- Symbiosis research
Background:
- Cryptomonads likely evolved from a eukaryotic host and an algal symbiont related to red algae.
- Organellar DNA is crucial for understanding phylogenetic relationships.
Purpose of the Study:
- To characterize the plastid (pt) DNA of the cryptomonad alga Pyrenomonas salina.
- To elucidate the phylogenetic position of cryptomonad plastids.
Main Methods:
- Restriction mapping of 127 kb circular ptDNA.
- Localization of ten protein genes and rRNA genes via hybridization and sequence homology.
- Sequencing of the plastidal small subunit (SSUr) RNA gene.
- Phylogenetic analysis using the neighborliness method.
Main Results:
- A restriction map of Pyrenomonas salina ptDNA was established, featuring an inverted repeat (IR) region and two single-copy regions.
- Genes for rRNA, key proteins (e.g., RuBisCO, photosystem II, ATP synthase), and ribosomal proteins were localized.
- Phylogenetic analysis of the SSUr gene indicates a close relationship between cryptomonad plastids and red algae.
Conclusions:
- The study provides a detailed characterization of Pyrenomonas salina plastid DNA.
- Phylogenetic data strongly supports the red algal origin of cryptomonad plastids.