Taxonomic revision of Halimeda (Bryopsidales, Chlorophyta) in south-western Australia

Cremen, Ma. Chiela M.; Huisman, John M.; Marcelino, Vanessa R.; Verbruggen, Heroen

doi:10.1071/sb15043

Cited by 38 publications

(34 citation statements)

References 17 publications

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“…DNA and RNA extraction, sequencing, and assembly. Total genomic DNA was extracted using a modified CTAB protocol (Cremen et al 2016), in which the CTAB extraction buffer was added directly to the cell pellet. Two paired-end libraries were constructed and sequenced on the Illumina NextSeq 500 platform (paired-end, 150 bp, first library~1.5 Gb, sec-ond~13 Gb).…”

Section: Methodsmentioning

confidence: 99%

The golden paradox – a new heterokont lineage with chloroplasts surrounded by two membranes

Wetherbee

Jackson

Repetti

et al. 2019

Journal of Phycology

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A marine, sand‐dwelling, golden‐brown alga is described from clonal cultures established from a high intertidal pool in southeastern Australia. This tiny, unicellular species, which we call the “golden paradox” (Chrysoparadoxa australica gen. et sp. nov.), is benthic, surrounded by a multilayered cell wall and attached to the substratum by a complex adhesive plug. Each vegetative cell gives rise to a single, naked zoospore with heterokont flagella that settles and may become briefly amoeboid prior to dividing. Daughter cells are initially amoeboid, then either permanently attach and return to the benthic stage or become motile again prior to final settlement. Two deeply lobed chloroplasts occupy opposite ends of the cell and are surrounded by only two membranes. The outer chloroplast membrane is continuous between the two chloroplasts via the outer membrane of the nuclear envelope. Only two membranes occupy the chloroplast–nucleus interface, the inner membrane of the nuclear envelope and the inner chloroplast membrane. A small pyrenoid is found in each chloroplast and closely abuts the nucleus or protrudes into it. It contains an unusual, membrane‐bound inclusion that stains with SYBR green but is unlikely to be a nucleomorph. Phylogenies inferred from a 10‐gene concatenated alignment show an early‐branching position within the PX clade. The unusual morphological features and phylogenetic position indicate C. australica should be classified as a new class, Chrysoparadoxophyceae. Despite an atypical plastid, exploration of the C. australica transcriptome revealed typical heterokont protein targeting to the plastid.

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Section: Methodsmentioning

confidence: 99%

The golden paradox – a new heterokont lineage with chloroplasts surrounded by two membranes

Wetherbee

Jackson

Repetti

et al. 2019

Journal of Phycology

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“…Total genomic DNA was extracted using a modified CTAB protocol (Cremen et al. ). The 18S rRNA gene was amplified and sequenced as described in Wetherbee and Verbruggen () and the sequences submitted to Genbank ().…”

Section: Methodsmentioning

confidence: 99%

A new marine prasinophyte genus alternates between a flagellate and a dominant benthic stage with microrhizoids for adhesion

Wetherbee

Marcelino

Costa

et al. 2019

Journal of Phycology

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Prasinophytes (Chlorophyta) are a diverse, paraphyletic group of planktonic microalgae for which benthic species are largely unknown. Here, we report a sand‐dwelling, marine prasinophyte with several novel features observed in clonal cultures established from numerous locations around Australia. The new genus and species, which we name Microrhizoidea pickettheapsiorum (Mamiellophyceae), alternates between a benthic palmelloid colony, where cell division occurs, and a planktonic flagellate. Flagellates are short lived, settle and quickly resorb their flagella, the basal bodies then nucleate novel tubular appendages, termed “microrhizoids”, that lack an axoneme and function to anchor benthic cells to the substratum. To our knowledge, microrhizoids have not been observed in any other green alga or protist, are slightly smaller in diameter than flagella, generally contain nine microtubules, are long (3–5 times the length of flagella) and are not encased in scales. Following settlement, cell divisions result in a loose, palmelloid colony, each cell connected to the substratum by two microrhizoids. Flagellates are round to bean‐shaped with two long, slightly uneven flagella. Both benthic cells and flagellates, along with their flagella, are encased in thin scales. Phylogenies based on the complete chloroplast genome of Microrhizoidea show that it is clearly a member of the Mamiellophyceae, most closely related to Dolichomastix tenuilepsis. More taxon‐rich phylogenetic analyses of the 18S rRNA gene, including metabarcodes from the Tara Oceans and Ocean Sampling Day projects, confidently show the distinctive nature of Microrhizoidea, and that the described biodiversity of the Mamiellophyceae is a fraction of its real biodiversity. The discovery of a largely benthic prasinophyte changes our perspective on this group of algae and, along with the observation of other potential benthic lineages in environmental sequences, illustrates that benthic habitats can be a rich ground for algal biodiscovery.

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“…We selected 24 taxa from eight bryopsidalean families for chloroplast genome sequencing, along with six taxa of Dasycladales as a close outgroup to Bryopsidales (Verbruggen et al, 2017). Total genomic DNA was extracted from silica gel-dried or ethanol-preserved thallus fragments using a modified CTAB protocol described in Cremen et al (2016). Lambia antarctica was field collected and frozen at -80 °C and was extracted using DNeasy Plant Mini Kit (Qiagen, Hilden, Germany).…”

Section: Taxon Sampling and Dna Extractionmentioning

confidence: 99%

Reassessment of the classification of Bryopsidales (Chlorophyta) based on chloroplast phylogenomic analyses

Cremen

Leliaert

West

et al. 2019

Molecular Phylogenetics and Evolution

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The Bryopsidales is a morphologically diverse group of mainly marine green macroalgae characterized by a siphonous structure. The order is composed of three suborders - Ostreobineae, Bryopsidineae, and Halimedineae. While previous studies improved the higher-level classification of the order, the taxonomic placement of some genera in Bryopsidineae (Pseudobryopsis and Lambia) as well as the relationships between the families of Halimedineae remains uncertain. In this study, we re-assess the phylogeny of the order with datasets derived from chloroplast genomes, drastically increasing the taxon sampling by sequencing 32 new chloroplast genomes. The phylogenies presented here provided good support for the major lineages (suborders and most families) in Bryopsidales. In Bryopsidineae, Pseudobryopsis hainanensis was inferred as a distinct lineage from the three established families allowing us to establish the family Pseudobryopsidaceae. The Antarctic species Lambia antarctica was shown to be an early-branching lineage in the family Bryopsidaceae. In Halimedineae, we revealed several inconsistent phylogenetic positions of macroscopic taxa, and several entirely new lineages of microscopic species. A new classification scheme is proposed, which includes the merger of the families Pseudocodiaceae, Rhipiliaceae and Udoteaceae into a more broadly circumscribed Halimedaceae, and the establishment of tribes for the different lineages found therein. In addition, the deep-water genus Johnson-sea-linkia, currently placed in Rhipiliopsis, was reinstated based on our phylogeny.

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Taxonomic revision of Halimeda (Bryopsidales, Chlorophyta) in south-western Australia

Cited by 38 publications

References 17 publications

The golden paradox – a new heterokont lineage with chloroplasts surrounded by two membranes

The golden paradox – a new heterokont lineage with chloroplasts surrounded by two membranes

A new marine prasinophyte genus alternates between a flagellate and a dominant benthic stage with microrhizoids for adhesion

Reassessment of the classification of Bryopsidales (Chlorophyta) based on chloroplast phylogenomic analyses

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