Skip to main content
Log in

The Plastid Genome of the Cryptophyte Alga, Guillardia theta: Complete Sequence and Conserved Synteny Groups Confirm Its Common Ancestry with Red Algae

  • Published:
Journal of Molecular Evolution Aims and scope Submit manuscript

Abstract.

The plastid genome of the cryptophyte alga Guillardia theta (121,524 bp) has been completely sequenced. The genome is 33% G+C and contains a short, nonidentical inverted repeat (4.9 kb) encoding the two rRNA cistrons. The large and small single-copy regions are 96.3 and 15.4 kb, respectively. Forty-six genes encoding proteins for photosynthesis, 5 genes for biosynthetic function, 5 genes involved in replication and division, 30 tRNA genes, 44 ribosomal protein genes (26 large subunit and 18 small subunit), 3 translation factors, 8 genes encoding components of the transcriptional machinery including 3 ycfs (hypothetical chloroplast frames), and 26 additional ycfs have been identified. There are eight ORFs larger than 50 amino acids, 3 of which have homologues on the plastid genome of the rhodophyte, Porphyra purpurea (Reith and Munholland 1995) and/or the Synechocystis genome (Kaneko et al. 1996) and can be designated new ycfs. Intergenic spacers are very short, no introns have been detected, and several genes overlap, all resulting in a very compact genome. In addition, large clusters of genes (such as those for the ribosomal proteins) are organized into single transcriptional units (Wang et al. 1997), again resulting in an economically organized genome. The cryptophyte plastid genome is almost completely comprised of clusters of genes that are found on the rhodophyte Porphyra purpurea, confirming its common ancestry with red algae. Furthermore, recombination events involving both tRNA genes and the rRNA cistrons appear to have been responsible for the structure of the cryptophyte plastid genome, including the formation of the inverted repeat.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

Author information

Authors and Affiliations

Authors

Additional information

Received: 16 June 1998 / Accepted: 20 August 1998

Rights and permissions

Reprints and permissions

About this article

Cite this article

Douglas, S., Penny, S. The Plastid Genome of the Cryptophyte Alga, Guillardia theta: Complete Sequence and Conserved Synteny Groups Confirm Its Common Ancestry with Red Algae. J Mol Evol 48, 236–244 (1999). https://doi.org/10.1007/PL00006462

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/PL00006462

Navigation