Virus-host coexistence in phytoplankton through the genomic lens

Abstract

Virus-microbe interactions in the ocean are commonly described by “boom and bust” dynamics, whereby a numerically dominant microorganism is lysed and replaced by a virus-resistant one. Here, we isolated a microalga strain and its infective dsDNA virus whose dynamics are characterized instead by parallel growth of both the microalga and the virus. Experimental evolution of clonal lines revealed that this viral production originates from the lysis of a minority of virus-susceptible cells, which are regenerated from resistant cells. Whole-genome sequencing demonstrated that this resistant-susceptible switch involved a large deletion on one chromosome. Mathematical modeling explained how the switch maintains stable microalga-virus population dynamics consistent with their observed growth pattern. Comparative genomics confirmed an ancient origin of this “accordion” chromosome despite a lack of sequence conservation. Together, our results show how dynamic genomic rearrangements may account for a previously overlooked coexistence mechanism in microalgae-virus interactions.

Eukaryotic virus composition can predict the efficiency of carbon export in the global ocean

“…The vast majority (95%) of non-VIPs may not have a significant impact on CEE, because they do not strongly impact the host population, for instance, by stably coexisting with their hosts. It is worth noting that experimental studies have reported cultures of algae with viruses that reach a stable co-existence state after a few generations ( Yau et al., 2020 ).…”

Metabolomic Insights into Marine Phytoplankton Diversity

“…Here, we explored the potential of an untargeted metabolomic approach including pigments, lipids, and other uncharacterized metabolites to investigate chemotaxonomic markers in 12 marine microalgal strains from 11 species, including 9 microalgae from the green lineage; the Mamiellales Ostreococcus tauri [20], O. mediterraneus [21], Bathycoccus prasinos [22], Micromonas commoda [23], and Mantoniella sp., the Chlorellales Picochlorum costavermella [24], and strains from basal groups Nephroselmis sp. and Pyramimonas sp.…”

Simplified Transformation of Ostreococcus tauri Using Polyethylene Glycol

“…They can be easily cultured in the laboratory, witnessed by more than 300 strains maintained in the Roscoff Culture Collection (RCC) in France [1], and they diverged at the base of the green lineage that includes land plants, thus providing a starting point for phylogenetic analyses [2]. Several of their streamlined haploid genomes have been completely sequenced and analysed [3,4,5,6,7,8], and they harbour a minimal number of genes for cellular processes, as reflected in the size of their nuclear genomes. Species in the genus Ostreococcus, for example, which so far includes four phylogenetically divergent [9] species with fully sequenced genomes (see [3,4,8] and ), have only 12–14 Mb of nuclear DNA, comparable to that of yeast (12.1 Mb) [10].…”

“…Several of their streamlined haploid genomes have been completely sequenced and analysed [3,4,5,6,7,8], and they harbour a minimal number of genes for cellular processes, as reflected in the size of their nuclear genomes. Species in the genus Ostreococcus, for example, which so far includes four phylogenetically divergent [9] species with fully sequenced genomes (see [3,4,8] and ), have only 12–14 Mb of nuclear DNA, comparable to that of yeast (12.1 Mb) [10]. This is much smaller than those of other model species in the green lineage such as mosses ( Physcomitrella patens , 476 Mb, [11]) Arabidopsis thaliana (135 Mb [12]) or maize (2.4 Gb [13]).…”