Phylogenetic relationships among basal-most arthrodontous mosses with special emphasis on the evolutionary significance of the Funariineae

The classification of the Bryopsida (mosses) has been based primarily on the variation of sporophytic characters i.e., architectural features of the peristome teeth that line the capsule mouth. Five arthrodontous peristome types have been recognized. Whether peristome types define natural groups and how they are evolutionary related has, however, remained unclear. Nucleotide sequence data from one nuclear and two chloroplast loci are generated and compiled to test two contrasting hypotheses regarding the ancestral peristome type in the Arthrodonteae. The genomic data partitions are incongruent with regard to the phylogenetic signal they carry. All phylogenetic analyses converge toward the polyphyly of the Funariineae and the Funariaceae. The Funariaceae are defined by the loss of a codon in the rps4 gene. Goniomitrium acuminatum, the type of the genus, lacks this deletion, and is always resolved within the Haplolepideae

Maximum-likelihood models for mapping genetic markers showing segregation distortion : 2. F2 populations

Dans la génération F2, la sélection naturelle des gamètes et des zygotes peut affecter les linkages génétiques. Une équation mathématique qui prend toutes les probabibilités de linkage en compte est développée. L'intégration des marqueurs génétiques dominants et codominants permet d'obtenir une courbe de probabilité asymptotique. La comparaison de l'utilité et de la précision des modèles montre que la prise en compte des marqueurs dominants seuls ne donne pas assez d'information sur le cas de distorsions de ségrégation. L'estimation de la fraction de recombinaisons entre les marqueurs codominants est peu affectée par la sélection, ce qui n'est pas le cas pour les marqueurs dominant

Global patterns of moss diversity: taxonomic and molecular inferences

Taxonomic and molecular data were utilized to test the hypothesis that moss diversity is greatest near the equator. Species richness estimates from 86 taxonomic checklists representing global moss diversity do not support the hypothesis that, in general, mosses are more species-rich in the tropics than at higher latitudes

Phylogenetic significance of the rpoA loss in the chloroplast genome of mosses

A recent survey of arthrodontous mosses revealed that their chloroplast genome lacks the gene encoding the alpha subunit of the RNA polymerase (i.e., rpoA), and that at least in Physcomitrella patens the gene has been transferred to the nuclear genome. Subsequently the gene was recorded from the cytoplasmic genome in Takakia and Sphagnum. Here we extend the survey to representatives of all major lineages of mosses to determine when in the evolutionary history of the Bryophyta the loss took place. Amplifications using primers annealing to the flanking regions of the rpoA gene yield a product that contains the gene in Takakia, Sphagnum, Andreaea, Oedipodium, Polytrichaceae, and Buxbaumia. The gene is lacking in all arthrodontous mosses, including Diphyscium but also in both species of Tetraphis. Reconstruction of the transfer on the phylogeny of mosses suggests (a) that the rpoA gene was lost twice and (b) that the gene was lost after the divergence of Buxbaumiidae and prior to the divergence of Diphyscium from the remaining Bryopsida

Phylogeny, character evolution, and biogeography of the gondwanic moss family Hypopterygiaceae (Bryophyta)

Phylogenetic relationships among the seven genera of the Hypopterygiaceae, represented by 14 of the 21 species recognized in the family, were reconstructed based on variation in nucleotide sequences of six nuclear, mitochondrial, and plastid loci

Deep sequencing of Ptilidium (Ptilidiaceae) suggests evolutionary stasis in liverwort plastid genome structure

Background and aims – Organellar genome sampling is patchy for non-vascular groups, with the earliest land plants poorly represented; currently only two liverworts, two mosses and one hornwort have sequenced, annotated plastid genomes. This is in part due to methodological difficulties that have hampered attempts to generate plastid genome data from liverworts. In this paper we present a method that overcomes some of the inherent difficulties by circumventing the need for plastid enrichment, but that also provides other valuable information from nuclear and mitochondrial regions including sequences from loci that may be phylogenetically useful, and potential population-level markers such as single nucleotide polymorphisms and microsatellites. Methods – A shotgun library developed from total genomic liverwort DNA was subjected to high-throughput pyrosequencing using the Roche 454 platform. Plastid reads were bioinformatically identified, assembled and annotated. To maximize usage of the vast number of reads generated using 454 sequencing technology, combined nuclear, mitochondrial and plastid contigs were also screened for microsatellite markers, and presumed nuclear contigs were scanned for protein domains. Key Results – This is the first plastid genome to be assembled for a leafy liverwort (i.e. Ptilidium) and also the first such genome to be sequenced using next generation technology for any bryophyte. The 119,007 base long plastid genome of Ptilidium pulcherrimum contains 88 protein-coding genes, four rRNAs and thirty tRNAs. The Inverted Repeat occurs between trn V-GAC and trn N-GUU. Functional copies of the two plastid-encoded sulphate import protein-coding genes (cysA and cysT) are absent, although pseudogenes are present in the same position that the functional genes occupy in Marchantia. Microsatellites: 197 novel potential primer pairs for P. pulcherrimum were found. Presumed nuclear Ptilidium contigs gave multiple hits to Class I transposable elements. Conclusions – The arrangement of genes is identical to the plastid of the complex thalloid liverwort Marchantia, suggesting that structural rearrangements are rare in hepatics. This dataset represents a valuable resource for novel phylogenetic and population level marker design in hepatics

Maximum-likelihood models for mapping genetic markers showing segregation distortion : 1. Backcross populations

Une approche du maximum de vraisemblance est utilisée pour estimer les fréquences de recombinaison entre des marqueurs présentant des distorsions de ségrégation dans des populations backcross. L'hypothèse faite ici est que les distorsions sont induites par des différences de viabilité entre gamètes ou zygotes dues à la présence d'un ou plusieurs allèles contre-sélectionnés. Nous montrons que l'estimateur de Bailey (1949) reste convergent donc efficace sous des conditions plus générales que celles définies par son auteur. Cet estimateur devrait donc être utilisé à la place de l'estimateur classique du maximum de vraisemblance. La question de la détection d'une liaison peut être affectée par les distorsions de ségrégation. (Résumé d'auteur

Evolution of the major moss lineages: phylogenetic analyses based on multiple gene sequences and morphology

Evolutionary relationships of mosses are still poorly understood, with family, order, and subclass circumscription and relationships remaining especially obscure

Geographical range in liverworts: does sex really matter?

AimWhy some species exhibit larger geographical ranges than others remains a fundamental, but largely unanswered, question in ecology and biogeography. In plants, a relationship between range size and mating system was proposed over a century ago and subsequently formalized in Baker's Law. Here, we take advantage of the extensive variation in sexual systems of liverworts to test the hypothesis that dioecious species compensate for limited fertilization by producing vegetative propagules more commonly than monoecious species. As spores are assumed to contribute to random long-distance dispersal, whereas vegetative propagules contribute to colony maintenance and frequent short-distance dispersal, we further test the hypothesis that monoecious species exhibit larger geographical ranges than dioecious ones.LocationWorldwide.MethodsWe used comparative phylogenetic methods to assess the correlation between range size and life history traits related to dispersal, including mating systems, spore size and production of specialized vegetative propagules.ResultsNo significant correlation was found between dioecy and production of vegetative propagules. However, production of vegetative propagules is correlated with the size of geographical ranges across the liverwort tree of life, whereas sexuality and spores size are not. Moreover, variation in sexual systems did not have an influence on the correlation between geographical range and production of asexual propagules.Main conclusionsOur results challenge the long-held notion that spores, and not vegetative propagules, are involved in long-distance dispersal. Asexual reproduction seems to play a major role in shaping the global distribution patterns of liverworts, so that monoecious species do not tend to display, on average, broader distribution ranges than dioecious ones. Our results call for further investigation on the spatial genetic structure of bryophyte populations at different geographical scales depending on their mating systems to assess the dispersal capacities of spores and asexual propagules and determine their contribution in shaping species distribution ranges

Powdery mildew of Vitis: Papillae (wall appositions) as a host response to infection

Powdery mildew, caused by Uncinula necator (ScHW.) BURR., of grapevines, as exemplified by cv. Rosette, induces papillae (wall appositions) inside periclinal cell walls. Papillae occur in epidermal and subepidermal cells of leaves, petioles, cluster rachises and green shoots. Aniline blue fluorescence tests showed the papillae to be composed of callose (polysaccharides). Ultrastructurally, they are characterized by vesicles in the electron-dense material.L'oïdium de la vigne: Papillae (appositions du paroi) comme un répons de l'hôte au infection L'oïdium, provoqué par Uncinula necator (ScHW.) BURR., de la vigne, par l'exemple du cultivar Rosette, produit papillae (appositions du paroi) en dedans des parois periclinales des cellules. On a vu les papillae dans des cellules épidermiques et subépidermiques des feuilles, des pétioles, des rafles et des rameaux verts. La fluorescence avec bleu d'aniline a démontré que les papillae consistent en callose (polysaccharides). Au microscope élect ronique à transmission, elles sont sombreuses aux électrons et elles se composent de vésicules