Ten Ostreobium (Ulvophyceae) strains from Great Barrier Reef corals as a resource for algal endolith biology and genomics

Abstract

Ostreobium is a genus of siphonous green algae that lives as an endolith in carbonate substrates under extremely limited light conditions and has recently been gaining attention due to its roles in reef carbonate budgets and its association with reef corals. Knowledge about this genus remains fairly limited due to the scarcity of strains available for physiological studies. Here, we report on 10 strains of Ostreobium isolated from coral skeletons from the Great Barrier Reef. Phenotypic diversity showed differences in the gross morphology and in few structures. Phylogenetic analyses of the tufA and rbcL put the strains in the context of the lineages identified previously through environmental sequencing. The chloroplast genomes of our strains are all around 80k bp in length and show that genome structure is highly conserved, with only a few insertions (some containing putative protein-coding genes) differing between the strains. The addition of these strains from the Great Barrier Reef to our toolkit will help develop Ostreobium as a model species for endolithic growth, low-light photosynthesis and coral-algal associations.

Six Newly Sequenced Chloroplast Genomes From Trentepohliales: The Inflated Genomes, Alternative Genetic Code and Dynamic Evolution

“…Trentepohlia and Cephaleuros differ in the conservation of gene clusters, for example, trnR-TCT–trnW-CCA ( Figure 6 ), and some gene clusters that are conserved across other Ulvophyceae were broken up in the Trentepohliales ( Supplementary Figure S4 ). High variability in chloroplast genomes architecture has also been observed among the Bryopsidales, which also lacks the quadripartite structure ( Cremen et al, 2018 ), but this is by no means a universal association as some higher-level groups of algae without quadripartite structure have exceptionally well-preserved synteny, for example the Ostreobineae ( Verbruggen et al, 2017 ; Pasella et al, 2021 ) and Nemaliales ( Costa et al, 2016 ).…”