Mediterranean Species of Caulerpa Are Polyploid with Smaller Genomes in the Invasive Ones

Varela-Álvarez, Elena; Garreta, Amèlia Gómez; Lluch, Jordi Rull; Soler, Noemi Salvador; Serrão, Ester A.; Siguán, María Antonia Ribera

doi:10.1371/journal.pone.0047728

Cited by 27 publications

(18 citation statements)

References 88 publications

(96 reference statements)

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“…In its vegetative phase, Caulerpa taxifolia is a haplophasic diploid. Caulerpa taxifolia has one of the smallest genome sizes in its genus (∼100 Mbp, approximately the size of the Arabidopsis thaliana genome) and unlike other Caulerpa species does not exhibit extensive endopolyploidy [12] , [13] .…”

Section: Resultsmentioning

confidence: 99%

An Intracellular Transcriptomic Atlas of the Giant Coenocyte Caulerpa taxifolia

Ranjan¹,

Townsley²,

Ichihashi³

et al. 2015

PLoS Genet

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Convergent morphologies have arisen in plants multiple times. In non-vascular and vascular land plants, convergent morphology in the form of roots, stems, and leaves arose. The morphology of some green algae includes an anchoring holdfast, stipe, and leaf-like fronds. Such morphology occurs in the absence of multicellularity in the siphonous algae, which are single cells. Morphogenesis is separate from cellular division in the land plants, which although are multicellular, have been argued to exhibit properties similar to single celled organisms. Within the single, macroscopic cell of a siphonous alga, how are transcripts partitioned, and what can this tell us about the development of similar convergent structures in land plants? Here, we present a de novo assembled, intracellular transcriptomic atlas for the giant coenocyte Caulerpa taxifolia. Transcripts show a global, basal-apical pattern of distribution from the holdfast to the frond apex in which transcript identities roughly follow the flow of genetic information in the cell, transcription-to-translation. The analysis of the intersection of transcriptomic atlases of a land plant and Caulerpa suggests the recurrent recruitment of transcript accumulation patterns to organs over large evolutionary distances. Our results not only provide an intracellular atlas of transcript localization, but also demonstrate the contribution of transcript partitioning to morphology, independent from multicellularity, in plants.

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Section: Resultsmentioning

confidence: 99%

An Intracellular Transcriptomic Atlas of the Giant Coenocyte Caulerpa taxifolia

Ranjan¹,

Townsley²,

Ichihashi³

et al. 2015

PLoS Genet

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“…Globally, whole genome duplication appears to require relatively stringent conditions; hybridization for instance is taxonomically widespread and frequent [76], whereas polyploidy is common in plants [77] and a few vertebrate lineages [78] but infrequent in most other taxonomic groups [37, 79, 80]. Even in plants, high variation in the frequency of polyploidy implies different propensities for polyploidization, or at least polyploid establishment, in different lineages [81].…”

Section: Discussionmentioning

confidence: 99%

Cryptic diversity, geographical endemism and allopolyploidy in NE Pacific seaweeds

et al. 2017

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BackgroundMolecular markers are revealing a much more diverse and evolutionarily complex picture of marine biodiversity than previously anticipated. Cryptic and/or endemic marine species are continually being found throughout the world oceans, predominantly in inconspicuous tropical groups but also in larger, canopy-forming taxa from well studied temperate regions. Interspecific hybridization has also been found to be prevalent in many marine groups, for instance within dense congeneric assemblages, with introgressive gene-flow being the most common outcome. Here, using a congeneric phylogeographic approach, we investigated two monotypic and geographically complementary sister genera of north-east Pacific intertidal seaweeds (Hesperophycus and Pelvetiopsis), for which preliminary molecular tests revealed unexpected conflicts consistent with unrecognized cryptic diversity and hybridization.ResultsThe three recovered mtDNA clades did not match a priori species delimitations. H. californicus was congruent, whereas widespread P. limitata encompassed two additional narrow-endemic species from California - P. arborescens (here genetically confirmed) and P. hybrida sp. nov. The congruence between the genotypic clusters and the mtDNA clades was absolute. Fixed heterozygosity was apparent in a high proportion of loci in P. limitata and P. hybrida, with genetic analyses showing that the latter was composed of both H. californicus and P. arborescens genomes. All four inferred species could be distinguished based on their general morphology.ConclusionsThis study confirmed additional diversity and reticulation within NE Pacific Hesperophycus/Pelvetiopsis, including the validity of the much endangered, modern climatic relict P. arborescens, and the identification of a new, stable allopolyploid species (P. hybrida) with clearly discernable ancestry (♀ H. californicus x ♂ P. arborescens), morphology, and geographical distribution. Allopolyploid speciation is otherwise completely unknown in brown seaweeds, and its unique occurrence within this genus (P. limitata possibly representing a second example) remains enigmatic. The taxonomic separation of Hesperophycus and Pelvetiopsis is not supported and the genera should be synonymized; we retain only the latter. The transitional coastline between Point Conception and Monterey Bay represented a diversity hotspot for the genus and the likely sites of extraordinary evolutionary events of allopolyploid speciation at sympatric range contact zones. This study pinpoints how much diversity (and evolutionary processes) potentially remains undiscovered even on a conspicuous seaweed genus from the well-studied Californian intertidal shores let alone in other, less studied marine groups and regions/depths.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0878-2) contains supplementary material, which is available to authorized users.

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“…Caulerpa nuclei are very small, approximately 2 µm in diameter (Varela-Álvarez et al, 2012). In addition, nuclei of various epiphytic and endophytic microbes are embedded in the cell wall or cytoplasm of Caulerpa (Singh & Reddy, 2014).…”

Section: Discussionmentioning

confidence: 99%

Differential gene expression in fronds and stolons of the siphonous macroalga, Caulerpa lentillifera

et al. 2019

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The green alga, Caulerpa lentillifera, is composed of a single cell with multiple nuclei, but it possesses structures analogous to leaves or fronds, stems or stolons, and roots or rhizoids. To understand molecular mechanisms involved in formation and function of these structures, we carried out RNA‐seq analysis of fronds and stolons (including rhizoids). Taking advantage of the decoded genome of C. lentillifera, the present RNA‐seq analysis addressed transcripts corresponding to 9,311 genes identified in the genome. RNA‐seq data suggested that 8,734 genes are expressed in sporophytes. Despite the siphonous body of the alga, differential gene expression was evident in the two structures. 1,027 (11.8%) and 1,129 (12.9%) genes were preferentially expressed in fronds and stolons, respectively, while the remaining 6,578 (75.3%) genes were expressed at the same level in both. Most genes preferentially expressed in fronds are associated with photosynthesis and plant hormone pathways, including abscisic acid signaling. In contrast, those preferentially expressed in stolons are associated with translation and DNA replication. These results indicate that gene expression is regulated differently between fronds and stolons, which probably governs the function of each structure. Together with genomic information, the present transcriptomic data provide genic information about development and physiology of this unique, siphonous organism.

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Mediterranean Species of Caulerpa Are Polyploid with Smaller Genomes in the Invasive Ones

Cited by 27 publications

References 88 publications

An Intracellular Transcriptomic Atlas of the Giant Coenocyte Caulerpa taxifolia

An Intracellular Transcriptomic Atlas of the Giant Coenocyte Caulerpa taxifolia

Cryptic diversity, geographical endemism and allopolyploidy in NE Pacific seaweeds

Differential gene expression in fronds and stolons of the siphonous macroalga, Caulerpa lentillifera

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