A Haploid System of Sex Determination in the Brown Alga Ectocarpus sp.

Ahmed, Shahzad; Cock, J. Mark; Pessia, Eugénie; Luthringer, R.; Cormier, Alexandre; Robuchon, Marine; Sterck, Lieven; Peters, Akira F.; Dittami, Simon M.; Corre, Matthieu Le; Valéro, Myriam; Aury, Jean‐Marc; Roze, Denis; Peer, Yves Van de; Bothwell, John H.; Marais, Gabriel; Coelho, Susana M.

doi:10.1016/j.cub.2014.07.042

Cited by 142 publications

(258 citation statements)

References 72 publications

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“…Unlike male-heterogametic (XX/XY) and female-heterogametic (ZZ/ZW) systems, in the UV sex determination system, recombination is suppressed on the sex chromosome in both sexes (Box 1). The UV sex determination system in brown algae, Ectocarpus , is estimated to be at least 70 Myr old, with evidence of reduced gene density and expression in the very small nonrecombining male-specific and female-specific regions (Ahmed 2014). Although genetic diversity was not explicitly analyzed, one expects diversity to be low in both the male- and female-specific regions.…”

Section: Algae Mosses and Fungimentioning

confidence: 99%

Genetic Diversity on the Sex Chromosomes

Sayres

2018

Genome Biology and Evolution

101

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Levels and patterns of genetic diversity can provide insights into a population’s history. In species with sex chromosomes, differences between genomic regions with unique inheritance patterns can be used to distinguish between different sets of possible demographic and selective events. This review introduces the differences in population history for sex chromosomes and autosomes, provides the expectations for genetic diversity across the genome under different evolutionary scenarios, and gives an introductory description for how deviations in these expectations are calculated and can be interpreted. Predominantly, diversity on the sex chromosomes has been used to explore and address three research areas: 1) Mating patterns and sex-biased variance in reproductive success, 2) signatures of selection, and 3) evidence for modes of speciation and introgression. After introducing the theory, this review catalogs recent studies of genetic diversity on the sex chromosomes across species within the major research areas that sex chromosomes are typically applied to, arguing that there are broad similarities not only between male-heterogametic (XX/XY) and female-heterogametic (ZZ/ZW) sex determination systems but also any mating system with reduced recombination in a sex-determining region. Further, general patterns of reduced diversity in nonrecombining regions are shared across plants and animals. There are unique patterns across populations with vastly different patterns of mating and speciation, but these do not tend to cluster by taxa or sex determination system.

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Section: Algae Mosses and Fungimentioning

confidence: 99%

Genetic Diversity on the Sex Chromosomes

Sayres

2018

Genome Biology and Evolution

101

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“…This is why only a handful of non-recombining sex chromosomes (Y, W, U, or V) have been fully sequenced and assembled to date (<15). This includes eight mammalian Y chromosomes (Bellott et al 2014), and other species which have small non-recombining regions: the liverwort Marchantia (Yamato et al 2007), the fish medaka (Kondo et al 2006), the green alga Volvox (Ferris et al 2010), the tree papaya (Wang et al 2012), and the brown alga Ectocarpus (Ahmed et al 2014). The scarcity of assembled Y is true even for well studied groups such as Drosophila .…”

Section: Introductionmentioning

confidence: 99%

SEX-DETector: A Probabilistic Approach to Study Sex Chromosomes in Non-Model Organisms

et al. 2016

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We propose a probabilistic framework to infer autosomal and sex-linked genes from RNA-seq data of a cross for any sex chromosome type (XY, ZW, and UV). Sex chromosomes (especially the non-recombining and repeat-dense Y, W, U, and V) are notoriously difficult to sequence. Strategies have been developed to obtain partially assembled sex chromosome sequences. Most of them remain difficult to apply to numerous non-model organisms, either because they require a reference genome, or because they are designed for evolutionarily old systems. Sequencing a cross (parents and progeny) by RNA-seq to study the segregation of alleles and infer sex-linked genes is a cost-efficient strategy, which also provides expression level estimates. However, the lack of a proper statistical framework has limited a broader application of this approach. Tests on empirical Silene data show that our method identifies 20–35% more sex-linked genes than existing pipelines, while making reliable inferences for downstream analyses. Approximately 12 individuals are needed for optimal results based on simulations. For species with an unknown sex-determination system, the method can assess the presence and type (XY vs. ZW) of sex chromosomes through a model comparison strategy. The method is particularly well optimized for sex chromosomes of young or intermediate age, which are expected in thousands of yet unstudied lineages. Any organisms, including non-model ones for which nothing is known a priori, that can be bred in the lab, are suitable for our method. SEX-DETector and its implementation in a Galaxy workflow are made freely available.

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“…Ectocarpus sp., a small filamentous alga, has been established as the model organism for the brown algae, inducing the generation of several genetic and genomic resources such as a fully sequenced genome1, a genetic map20 and transcriptomic data1921. Previously named Ectocarpus siliculosus , it has recently become clear that this taxa corresponds to a separate species that has not been described previously22 and we therefore refer to the species provisionally as Ectocarpus sp.…”

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confidence: 99%

High-density genetic map and identification of QTLs for responses to temperature and salinity stresses in the model brown alga Ectocarpus

Avia

Coelho

Montecinos

et al. 2017

Sci Rep

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Deciphering the genetic architecture of adaptation of brown algae to environmental stresses such as temperature and salinity is of evolutionary as well as of practical interest. The filamentous brown alga Ectocarpus sp. is a model for the brown algae and its genome has been sequenced. As sessile organisms, brown algae need to be capable of resisting the various abiotic stressors that act in the intertidal zone (e.g. osmotic pressure, temperature, salinity, UV radiation) and previous studies have shown that an important proportion of the expressed genes is regulated in response to hyposaline, hypersaline or oxidative stress conditions. Using the double digest RAD sequencing method, we constructed a dense genetic map with 3,588 SNP markers and identified 39 QTLs for growth-related traits and their plasticity under different temperature and salinity conditions (tolerance to high temperature and low salinity). GO enrichment tests within QTL intervals highlighted membrane transport processes such as ion transporters. Our study represents a significant step towards deciphering the genetic basis of adaptation of Ectocarpus sp. to stress conditions and provides a substantial resource to the increasing list of tools generated for the species.

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A Haploid System of Sex Determination in the Brown Alga Ectocarpus sp.

Cited by 142 publications

References 72 publications

Genetic Diversity on the Sex Chromosomes

Genetic Diversity on the Sex Chromosomes

SEX-DETector: A Probabilistic Approach to Study Sex Chromosomes in Non-Model Organisms

High-density genetic map and identification of QTLs for responses to temperature and salinity stresses in the model brown alga Ectocarpus

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