English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background  The Streptophyta comprises all land plants and six groups of charophycean green algae. The scaly biflagellate  Mesostigma viride  (Mesostigmatales) and the sarcinoid  Chlorokybus atmophyticus  (Chlorokybales) represent the earliest diverging lineages of this phylum. In trees based on chloroplast genome data, these two charophycean green algae are nested in the same clade. To validate this relationship and gain insight into the ancestral state of the mitochondrial genome in the Charophyceae, we sequenced the mitochondrial DNA (mtDNA) of  Chlorokybus  and compared this genome sequence with those of three other charophycean green algae and the bryophytes  Marchantia polymorpha  and  Physcomitrella patens .    Results  The  Chlorokybus  genome differs radically from its 42,424-bp  Mesostigma  counterpart in size, gene order, intron content and density of repeated elements. At 201,763-bp, it is the largest mtDNA yet reported for a green alga. The 70 conserved genes represent 41.4% of the genome sequence and include  nad10  and  trnL (gag), two genes reported for the first time in a streptophyte mtDNA. At the gene order level, the  Chlorokybus  genome shares with its  Chara ,  Chaetosphaeridium  and bryophyte homologues eight to ten gene clusters including about 20 genes. Notably, some of these clusters exhibit gene linkages not previously found outside the Streptophyta, suggesting that they originated early during streptophyte evolution. In addition to six group I and 14 group II introns, short repeated sequences accounting for 7.5% of the genome were identified. Mitochondrial trees were unable to resolve the correct position of  Mesostigma , due to analytical problems arising from accelerated sequence evolution in this lineage.    Conclusion  The  Chlorokybus  and  Mesostigma  mtDNAs exemplify the marked fluidity of the mitochondrial genome in charophycean green algae. The notion that the mitochondrial genome was constrained to remain compact during charophycean evolution is no longer tenable. Our data raise the possibility that the emergence of land plants was not associated with a substantial gain of intergenic sequences by the mitochondrial genome.

An unexpectedly large and loosely packed mitochondrial genome in the charophycean green alga Chlorokybus atmophyticus