The Amborella Genome and the Evolution of Flowering Plants

Amborella trichopoda, an endemic species to New Caledonia, is the most early-diverging taxa of flowering plants (angiosperms, Figure 1). As such, the sequencing of its genome was of considerable interest for the investigation of the emergence and evolution of this highly diverse lineage presenting at least 350’00 species. In this work, the Amborella genome project (http://www.amborella.org/) reports the draft genome sequence for A. trichopoda. Notably, it was used as reference for the reconstruction of genomic features and architecture of the most recent common ancestor of living angiosperms, the investigation of gene families specific to flowering plants, and the investigation of the Amborella population structure. Genome structure The identification of frequent duplicated collinear genes (Figure 2a) within A. trichopoda genome provides evidence of an a ancient whole genome duplication (WGD). WGD is known to be a pervasive feature in the evolution of plants, with modern plants frequently presenting traces of multiple past duplication events. Thus, a comparison with Vitis vinifera (grape) showed that the genome of A. trichopoda is almost entirely covered by three syntenic grape regions (Figure 2b and 2c). This 1:3 relationship between those two genomes indicates that the WGD detected in A. trichopoda occurred in the common ancestor …

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Single and independent mutations lead to an adaptive and complex color phenotype in deer mice living on the light-colored soils of the Nebraska Sand Hills

Pleiotropy of genes is often the main solution to explain genetic basis of complex phenotypes (i.e., those composed of multiple traits). But dissection of those genes or loci are rarely studied, and it remains unclear which of single pleiotropic mutations or multiple mutations with independent effects are responsible to elaborate complex phenotypes. Linnen et al. are interested in coloration of the deer mice (Peromyscus maniculatus) present on the light-colored soils of the Nebraska Sand Hills. Adaptation for crypsis is the strongest hypothesis to explain prevalence of the light morph compared to the black morph,  and they wanted to dissect the genetic basis of this adaptation. This study is composed of two main parts : first to understand and to evaluate the complexity of coloration phenotype and then to find the mutations responsible of those variation in traits and on which morph selection is acting on. First of all, they implemented an experimentation with plasticine models to count the number of attacks on each coloration morph. As they expected, statistical test reveals that the dark models are significantly more attacked than light models. Closer inspection reveals multiple pigmentation traits and pattern that differ between the light and the dark morph to compose complex coloration …

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Patterns of population epigenomic diversity

In my point of vue, this paper is interesting because it’s in my domain of interest but very difficult to understand because they put lot of technical word without definition and they say very often see references, as it’s described in this paper making this paper very difficult to understand. Also in this paper, the aim is not very clear and also there is no conclusion. I have the feeling that they don’t know what they can conclure. But I will try to explain in few words the paper… About the introduction. It is well know that natural epigenetic variation provides a source for the generation of phenotypic diversity but it remains unclear how this epigenetic variation contributes to this diversity and the relationship between genetic variation and epigenetic mechanisms. Epigenetic is defined by heritable modification of genes expression. This modification can be heritate during the meiosis and/or mitosis but does not affect a changing in DNA sequences. Epigenetic modifications are mainly defined by cytosine methylation in a DNA level or histone methylation, histone acetylation. In plant including Arabidopsis thaliana model, basically there are 3 different patterns of methylation: methylation in a cytosine in a CG context, on a CHG …

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