Mitochondrial and Plastid Genomes of the Monoraphid Diatom Schizostauron trachyderma

Abstract

We provide for the first time the complete plastid and mitochondrial genomes of a monoraphid diatom: Schizostauron trachyderma. The mitogenome is 41,957 bp in size and displays two group II introns in the cox1 gene. The 187,029 bp plastid genome features the typical quadripartite architecture of diatom genomes. It contains a group II intron in the petB gene that overlaps the large single-copy and the inverted repeat region. There is also a group IB4 intron encoding a putative LAGLIDADG homing endonuclease in the rnl gene. The multigene phylogenies conducted provide more evidence of the proximity between S. trachyderma and fistula-bearing species of biraphid diatoms.

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.…”

“…For this dataset, sequences were aligned with MEGAX (Kumar et al, 2018) and manually trimmed to a final length of 618 bp. For the multigene phylogenies, the datasets were prepared in a similar way to Goŕecka et al (2021), reusing most of these previous datasets by appending them. All protein-coding genes were concatenated by alphabetical order and aligned using MAFFT 7 (Katoh & Standley, 2013) (-auto option) and trimmed by trimAl (Capella-Gutieŕrez et al, 2009), (-automated1 option).…”

Xenobennettella coralliensis a new monoraphid diatom genus characterized by the alveolate sternum valve with cavum, observed from coral reef habitats

“…Apparently, the cavum in Xenobennettella is possibly another example of homoplasy in diatom valve ultrastructure, along with the alveolate cross-section. With the documented paraphyly of monoraphid diatoms ( Davidovich et al, 2017 ; Górecka et al, 2021 ; Riaux-Gobin et al, 2021 ), we are hopeful that we will be able to test in the future the hypothesis that this genus may represent a secondary gain of the monoraphid frustule close to the pinnularioid diatoms, based on similarities in the alveolate valve ultrastructure.…”

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

“…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.…”

“…Compared with their diversity and importance, the number of diatom whole organellar genomes available in public databases is still relatively small. Those available, however, have demonstrated that chloroplast genome gene rearrangements within diatom genera can evolve at a rapid rate compared to embryophytes | James A. Nienow 3 (Górecka et al, 2021;Hamsher et al, 2019) and that mitochondrial genomes can provide evidence of speciation events (Guillory et al, 2018;Wang et al, 2022). The purpose of this report is to present morphological analyses and report the production of genetic markers for Gomphonema parvulum, a cosmopolitan freshwater diatom with a wide range of morphological variations (Dawson, 1972;Kociolek et al, 2015).…”