Chaetosphaeridium globosum. Chaetosphaeridium globosum

Chaetosphaeridium is a genus of small, unicellular, freshwater chlorophyte. The cells are ovoid or spherical and can be found in groups forming branched filaments that are connected by hyaline tubes. Each cell has a parietal chloroplast, which contains a pyrenoid, and it bears a long hair like structure that is formed by extension of the cell wall that has a basal sheath. Oogamous reproduction has been reported and asexual reproduction is by the formation of biflagellate zoospores. Chaetosphaeridium belongs to the order Choleochaetales which has great evolutionary and environmental importance as it has often been thought of as the group closest to the land plants. Mitochondrial and chloroplast genome of Chaetosphaeridium globosum has been fully sequenced in order to understand the evolution of organelle genomes in Streptophyta. Chloroplast DNA (131,183 bp) was found to be strikingly similar to land-plant DNA in terms of gene content (124 genes), intron composition (18 introns), and gene order, while the mitochondrial DNA (56,574 bp) was found to be more compact than land plants and featured differences at the levels of size, intron composition (11 introns), and gene order.