Abstract Detail

Genomics / Proteomics

Allen, Jessica [1], Mccourt, Richard [2], Karol, Kenneth [3].

Structural evolution of mitochondrial genomes in early diverging algal lineages.

Prasinophytes are a paraphyletic assemblage of green algae that include the earliest diverging lineages in Chlorophyta. These single-celled, planktonic organisms are found worldwide in marine and freshwater habitats. Lineages are recognizable by characters associated with scale morphology, flagellar apparatus, and processes of cell division. Evolutionary relationships among these lineages are poorly understood, which limits our ability to test hypotheses about early algal evolution. Currently, seven distinct prasinophyte lineages have been identified (Clades I-VII), and four completely sequenced mitochondrial genomes from clades II, III, and V are available. We generated mitochondrial genomes from three additional lineages (Clade I, IV, VI) and increased taxon sampling in the Mamiellales (Clade II), the most diverse group of prasinophytes. An architectural feature frequently found in plastid genomes is an inverted repeat (IR) located between the large single copy and small single copy region, which usually contains genes that code for the small and large subunits of the ribosome. Typically, green plant mitochondrial genomes do not contain an IR. However, of the completed mitochondrial genomes sequenced throughout green plants, only two prasinophyte mitochondrial genomes (both Mamiellophyceae; Clade II), have been found to contain IRs as part of their mitochondrial genome architecture. Interestingly, the genes contained in these mitochondrial IRs also included the large and small subunit ribosomal genes, as well as a few protein-coding genes (e.g., cox1, atp8). Newly sequenced mitochondrial genomes from Pyramimonadales (Clade I) and Chlorodendrales (Clade IV) also contain IRs, while mitochondrial genomes for Mamiellales (Clade II) and Prasinococcales (Clade VI) include members that have an IR and other members that do not; illustrating the plasticity of this architectural feature in prasinophyte mitochondrial genomes. Inverted repeats have not been indentified in completely sequenced mitochondrial genomes for representatives of Clades III and V, and mitochondrial genomes have not yet been sequenced for representatives of Clade VII. Details of genome architecture, gene content, and evolutionary relationships among prasinophyte lineages will be discussed.

Broader Impacts:

1 - The New York Botanical Garden, Institute of Systematic Botany, Bronx, NY, 10458-5126, USA
2 - Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, USA
3 - The New York Botanical Garden, Cullman Molecular Systematics Program, Bronx, NY, 10458-5126, USA

Keywords:
mitochondrial genome
prasinophyte
Chlorophyta
Algae
Inverted repeat
Phylogenomics.

Presentation Type: Oral Paper:Papers for Topics
Session: 24
Location: Newberry/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 10:30 AM
Number: 24003
Abstract ID:708
Candidate for Awards:Margaret Menzel Award