Abstract
The systematics of the green algal class Ulvophyceae have been difficult to resolve with ultrastructural and molecular phylogenetic analyses. Therefore, we investigated relationships among ulvophycean orders by determining the distribution of two discrete genetic characters previously identified only in the order Dasycladales. First, Acetabularia acetabulum uses the core translation GTPase Elongation Factor 1α (EF-1α) while most Chlorophyta instead possess the related GTPase Elongation Factor-Like (EFL). Second, the nuclear genomes of dasycladaleans A. acetabulum and Batophora oerstedii use a rare non-canonical genetic code in which the canonical termination codons TAA and TAG instead encode glutamine. Representatives of Ulvales and Ulotrichales were found to encode EFL, while Caulerpales, Dasycladales, Siphonocladales, and Ignatius tetrasporus were found to encode EF-1α, in congruence with the two major lineages previously proposed for the Ulvophyceae. The EF-1α of I. tetrasporus supports its relationship with Caulerpales\Dasycladales\ Siphonocladales, in agreement with ultrastructural evidence, but contrary to certain small subunit rRNA analyses that place it with Ulvales\Ulotrichales. The same non-canonical genetic code previously described in A. acetabulum was observed in EF-1α sequences from Parvocaulis pusillus (Dasycladales), Chaetomorpha coliformis, and Cladophora cf. crinalis (Siphonocladales), whereas Caulerpales use the universal code. This supports a sister relationship between Siphonocladales and Dasycladales and further refines our understanding of ulvophycean phylogeny.
Original language | English (US) |
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Pages (from-to) | 367-372 |
Number of pages | 6 |
Journal | Journal of Eukaryotic Microbiology |
Volume | 56 |
Issue number | 4 |
DOIs | |
State | Published - Jul 2009 |
Externally published | Yes |
Keywords
- Caulerpales
- Chlorophyta
- Dasycladales
- Elongation factors
- Green algae
- Ignatius tetrasporus
- Systematics
- Taxonomy
- Ulotrichales
- Ulvales
ASJC Scopus subject areas
- Microbiology