Life-cycle-generation-specific developmental processes are modified in the<i>immediate upright</i>mutant of the brown alga<i>Ectocarpus siliculosus</i>

Peters, Akira F.; Scornet, Delphine; Ratin, Morgane; Charrier, Bénédicte; Monnier, Annabelle; Merrien, Y; Corre, Erwan; Coelho, Susana M.; Cock, J. Mark

doi:10.1242/dev.016303

Cited by 111 publications

(143 citation statements)

References 25 publications

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“…S1A), parthenotes of the oro mutant exhibited both morphological and functional features typical of gametophytes. The first cell division was asymmetrical, rather than being symmetrical as in the wild-type partheno-sporophyte (18), resulting in cells with rhizoid and upright filament identities ( Fig. 1 A-C).…”

Section: Results Ouroboros Mutant Parthenotes Closely Resemble Wild-typementioning

confidence: 95%

“…One experimental advantage of this parthenogenesis is that mutations affecting sporophyte development are directly expressed phenotypically in haploid partheno-sporophytes, facilitating mutant screens (18). A spontaneous mutation (immediate upright; imm), in which the sporophyte generation exhibits several characteristics of the gametophyte, including an asymmetric initial cell division and absence of a basal system of prostrate filaments, has recently been described (18). Here we characterize a second Ectocarpus life cycle mutant, ouroboros (oro), which exhibits homeotic conversion of the sporophyte generation into a fully functional gametophyte.…”

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OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus

Coelho

Godfroy

Arun

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The brown alga Ectocarpus siliculosus has a haploid–diploid life cycle that involves an alternation between two distinct generations, the sporophyte and the gametophyte. We describe a mutant, ouroboros ( oro ), in which the sporophyte generation is converted into a functional, gamete-producing gametophyte. The life history of the mutant thus consists of a continuous reiteration of the gametophyte generation. The oro mutant exhibited morphological features typical of the gametophyte generation and accumulated transcripts of gametophyte generation marker genes. Genetic analysis showed that oro behaved as a single, recessive, Mendelian locus that was unlinked to the IMMEDIATE UPRIGHT locus, which has been shown to be necessary for full expression of the sporophyte developmental program. The data presented here indicate that ORO is a master regulator of the gametophyte-to-sporophyte life cycle transition and, moreover, that oro represents a unique class of homeotic mutation that results in switching between two developmental programs that operate at the level of the whole organism.

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Section: Results Ouroboros Mutant Parthenotes Closely Resemble Wild-typementioning

confidence: 95%

mentioning

confidence: 99%

OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus

Coelho

Godfroy

Arun

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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135

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“…Microarrays were composed of 1,152 PCR products, corresponding to sporophytic and gametophytic tissues, and are fully described by Peters et al (2008). Targets were prepared from RNA extracted from 200 mg of ground sporophytic material and treated with NAA (see culture conditions), and RNA was extracted with an extraction buffer (100 mM Tris-HCl, pH 7.5, 1.5 M NaCl, 2% cetyl-trimethyl-ammonium bromide, 50 mM EDTA, and 50 mM dithiothreitol) for 1 h with shaking and then with 1 volume of chloroform: isoamyl alcohol (24:1).…”

Section: Microarraymentioning

confidence: 99%

“…RNAs were precipitated for 2 h with 2.4 M lithium chloride and 1% b-mercaptoethanol and then with a phenolchloroform extraction and alcohol precipitation. Microarray hybridizations were performed as described by Peters et al (2008). The data are available at the Array Express at EMBL-EBI with accession number E-MEXP-1716.…”

Section: Microarraymentioning

confidence: 99%

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Auxin Metabolism and Function in the Multicellular Brown AlgaEctocarpus siliculosus

et al. 2010

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Ectocarpus siliculosus is a small brown alga that has recently been developed as a genetic model. Its thallus is filamentous, initially organized as a main primary filament composed of elongated cells and round cells, from which branches differentiate. Modeling of its early development suggests the involvement of very local positional information mediated by cell-cell recognition. However, this model also indicates that an additional mechanism is required to ensure proper organization of the branching pattern. In this paper, we show that auxin indole-3-acetic acid (IAA) is detectable in mature E. siliculosus organisms and that it is present mainly at the apices of the filaments in the early stages of development. An in silico survey of auxin biosynthesis, conjugation, response, and transport genes showed that mainly IAA biosynthesis genes from land plants have homologs in the E. siliculosus genome. In addition, application of exogenous auxins and 2,3,5-triiodobenzoic acid had different effects depending on the developmental stage of the organism, and we propose a model in which auxin is involved in the negative control of progression in the developmental program. Furthermore, we identified an auxin-inducible gene called EsGRP1 from a small-scale microarray experiment and showed that its expression in a series of morphogenetic mutants was positively correlated with both their elongated-to-round cell ratio and their progression in the developmental program. Altogether, these data suggest that IAA is used by the brown alga Ectocarpus to relay cell-cell positional information and induces a signaling pathway different from that known in land plants.

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Genomics of Algae

Heijde¹,

Bowler²

2009

Encyclopedia of Life Sciences

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Algae are dominant contributors to primary production and have a major impact on biogeochemical cycles because of their unique metabolisms. Few algal genomes have so far been characterized, although whole genome sequences have now been generated from representatives of the green, red and brown algae. In addition, numerous projects are progressing to define algal transcriptomes using expressed sequence tags (ESTs) and microarrays. Multiple efforts based on comparative and functional genomics approaches have already generated an influx of exciting data about evolutionary origins and functional innovations of different algal species dispersed throughout the eukaryotic tree of life. Key concepts: Algal species have little common phylogeny and are widely dispersed throughout the eukaryotic tree of life. Red and green algae lie within the Archaeplastida whereas brown algae lie within the Stramenopile and Alveolata lineages. Brown algae have secondary plastids, thought to be derived from secondary endosymbiosis. Chlamydomonas reinhardtii represents the best‐studied experimental system for algae. Diatom genomes are highly chimeric in nature, with genes derived from both partners of the secondary endosymbiosis, as well as large numbers of bacterial genes acquired by horizontal gene transfer. The existence of C4 photosynthesis in algae has not yet been conclusively demonstrated. Distinct algal species often comprise ecotypes optimized for growth in specific environmental conditions.

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Life-cycle-generation-specific developmental processes are modified in theimmediate uprightmutant of the brown algaEctocarpus siliculosus

Cited by 111 publications

References 25 publications

OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus

OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus

Auxin Metabolism and Function in the Multicellular Brown AlgaEctocarpus siliculosus

Genomics of Algae

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