Extreme Enlargement of the Inverted Repeat Region in the Plastid Genomes of Diatoms from the Genus Climaconeis

Abstract

We sequenced the plastid genomes of three diatoms from the genus Climaconeis, including two strains formerly designated as Climaconeis scalaris. At 208,097 and 216,580 bp, the plastid genomes of the latter strains are the largest ever sequenced among diatoms and their increased size is explained by the massive expansion of the inverted repeat region. Important rearrangements of gene order were identified among the two populations of Climaconeis cf. scalaris. The other sequenced Climaconeis chloroplast genome is 1.5 times smaller compared with those of the Climaconeis cf. scalaris strains and it features an usual quadripartite structure. The extensive structural changes reported here for the genus Climaconeis are compared with those previously observed for other algae and plants displaying large plastid genomes.

The blue diatom Haslea ostrearia from the Indian Ocean coast of South Africa, with comparative analysis of Haslea organellar genomes

“…Similar observations have previously been reported for H. silbo (Gastineau et al, 2021a) and the distantly related diatom Cylindrotheca fusiformis Reimann & J.C. Lewin (Hildebrand et al, 1992). The plastomes of several diatoms are known to carry recombinase or integrase genes (e.g., Gastineau et al, 2021b;Goŕecka et al, 2021). However, it is not clear whether they feature circular plasmids that share homology with these genes.…”

Mitochondrial and Plastid Genomes of the Monoraphid Diatom Schizostauron trachyderma

“…cassiae Kociolek and Stoermer, and Phaeodactylum tricornutum Bohlin. With the exception of P. tricornutum , all these species belong to the same clade in the plastid multigene phylogeny presented below, but this clade also contains Climaconeis spp., among which this gene was not found [ 32 ]. None of the Bacillariaceae ( Nitzschia spp., Tryblionella apiculata W.Gregory) or Naviculaceae ( Haslea spp., Seminavis robusta D.B.…”

The chloroplast and mitochondrial genomes of two Gomphonema parvulum (Bacillariophyta) environmental isolates from South Carolina (United States) and Virginia (United States)

“…parvulum and Gomphonesis minuta , it was 84.82%. The chloroplast genome gene content among raphid pennate diatoms is relatively conserved, but the sizes of intergenic regions and gene order are not (Gastineau et al., 2021; Górecka et al., 2021; Ruck et al., 2014). The addition of G .…”

“…The sequence identity between the G. parvulum and D. geminata chloroplast genomes was 84.27%, and between G. parvulum and Gomphonesis minuta, it was 84.82%. The chloroplast genome gene content among raphid pennate diatoms is relatively conserved, but the sizes of intergenic regions and gene order are not (Gastineau et al, 2021;Górecka et al, 2021;Ruck et al, 2014). The addition of G. parvulum now provides three chloroplast genomes within the Cymbellales, demonstrating no changes in gene synteny.…”