Evolutionary relationships among cyanobacteria and green chloroplasts

Abstract

The 16S rRNAs from 29 cyanobacteria and the cyanelle of the phytoflagellate Cyanophora paradoxa were partially sequenced by a dideoxynucleotide-terminated, primer extension method. A least-squares distance matrix analysis was used to infer phylogenetic trees that include green chloroplasts (those of euglenoids, green algae, and higher plants only support the conclusion of previous workers that the cyanobacteria and green chloroplasts form a coherent phylogenetic group but also suggest that the chloroplast lineage, which includes the cyanelle of C. paradoxa, is not just a sister group to the free-living forms but rather is contained within the cyanobacterial radiation.The cyanobacteria are one of the most morphologically diverse and conspicuously successful procaryotic groups. It is generally believed that the cyanobacteria were the first major group of phototrophs to arise with a two-stage photosynthetic pathway capable of oxidizing water to produce molecular oxygen. Geochemical and fossil evidence indicates that in the Precambrian Era they caused the transition in the Earth's atmosphere from its primordial, anaerobic state to its current, aerobic condition (19,36,43). Moreover, molecular phylogenetic analysis of c-type cytochrome and rRNA sequences have established a relationship between cyanobacteria and the green (euglenoids, green algae, and higher plants) and red (rhodophyte) chloroplasts, thus supporting the procaryotic origins of chloroplasts.Because of their ubiquity, rRNA sequences are particularly useful for establishing evolutionary relationships among diverse organisms. Woese and colleagues, using partial (RNase Tl-generated oligonucleotide catalogs) and complete 16S rRNA sequences, have defined about 10 major divisions (phyla) of eubacteria (45). The cyanobacteria are one of these phyla. However, too few strains (eight) of cyanobacteria had been investigated to develop a comprehensive overview of the diversity of the group.We have used a method for directly sequencing 16S rRNA to explore the evolutionary relationships among 30 representatives of the diverse cyanobacterial groups, including the photosynthetic organelle of the phytoflagellate Cyanophora paradoxa. The results shed new light on the relative ages of * Corresponding author. t Present address:

Gut content microbiota of introduced bigheaded carps ( Hypophthalmichthys spp.) inhabiting the largest shallow lake in Central Europe

“…Chloroplast sequences were also retrieved by Bacteria-specific primers, since plastids represent a distinct lineage within phylum Cyanobacteria (Giovannoni et al, 1988). These sequences were analyzed separately, owing to that plastid 16S rRNA gene references are underrepresented in the ARB-SILVA database.…”

Localization and expression of the closely linked cyanelle genes for RNase P RNA and two transfer RNAs

“…One putative intermediate in plastid evolution is the unicellular photosynthetic protist Cyanophora paradoxa. The pigment and cell wall composition of its photosynthetic orgenelles or cyanelles resemble that of free-living ~,yan~bacteria, whereas the dramatically reduced size and orgstnization of their genome is more similar to chloroplasts [4,$|, Sequence derived phylogenetic trees position the cyanelle in a coherent group together with cyanobacteria and green plastids [6,7]; several genes that hstve been lost from chloropint genomes early in plant evolution are present in the cyahelle genome, Taken together, these facts support the idea that this orpnelle might be considered st remnant of an early star.ca of plastid evolution, and thus serve as a model to study the molecular evolution of RNstse P, an ancient and ubiquitous RNA enzyme, in plastids of different origin.…”

Phylogenetic analyses of Synechococcus strains (cyanobacteria) using sequences of 16S rDNA and part of the phycocyanin operon reveal multiple evolutionary lines and reflect phycobilin content.

“…In addition to analysis of 16S rRNA gene sequences (Giovannoni et al, 1988 ;Honda et al, 1999 ;Neilan et al, 1997 ;Otsuka et al, 1998 ;Turner et al, 1999 ;Urbach et al, 1998 ;Wilmotte, 1994), genes encoding the major light-harvesting accessory pigment proteins, particularly the phycocyanin (PC) operon (cpc), including the intergenic spacer (IGS) between cpcB and cpcA and the corresponding flanking regions (cpcBA-IGS), have been targeted for phylogenetic studies of cyanobacteria (Barker et al, 1999 ;Bolch et al, 1996 ;Hayes & Barker, 1997 ;Neilan et al, 1995).…”