Comparative phylogenies and host specialization in the alder ectomycorrhizal fungi Alnicola, Alpova and Lactarius (Basidiomycota) in Europe

<p>Abstract</p> <p>Background</p> <p>Mycorrhizal fungi form intimate associations with their host plants that constitute their carbon resource and habitat. <it>Alnus </it>spp. (Betulaceae) are known to host an exceptional species-poor and specialized ectomycorrhizal (ECM) fungal community compared to other tree species, but the host-specificity pattern and its significance in terms of fungal diversification and speciation remain poorly documented. The degree of parallel speciation, host switching, and patterns of biogeography were explored in the historical associations between alders and three ECM taxa of Basidiomycetes: <it>Alnicola </it>(Agaricales), <it>Alpova </it>(Boletales), and <it>Lactarius </it>(Russulales). The aim was to develop an evolutionary framework on host specificity and diversification of Basidiomycetes in this highly specialized plant-fungus symbiosis.</p> <p>Results</p> <p>Sporocarps of <it>Alnicola </it>(220), <it>Lactarius </it>(61) and <it>Alpova </it>(29) were collected from stands of the four European alder species (<it>A. alnobetula </it>including the endemic subsp. <it>suaveolens </it>in Corsica, <it>A. cordata</it>, <it>A. glutinosa</it>, <it>A. incana</it>) in Western Europe (mainly in France and Austria), from 1995 to 2009. Specimens were morphologically identified to the species level. From these, 402 sequences of four DNA regions (ITS, rpb2, gpd, and the V9 domain of the mit-SSU rDNA) were successfully obtained and analyzed in addition with 89 sequences available in GenBank and UNITE databases. Phylogenetic analyses were conducted on all sequence data sets (individual and combined) using maximum likelihood reconstruction and Bayesian inference. Fungal phylogenies are compared and discussed in relation to the host, with a focus on species boundaries by associating taxonomic, systematic and molecular information.</p> <p>Conclusions</p> <p>Patterns of host specificity and phylogenies of <it>Alnicola </it>and <it>Lactarius </it>suggest coevolution as a basal factor of speciation in relation with the subgeneric diversification of <it>Alnus</it>, possibly due to the very selective pressure of the host. A second element of the historical associations between <it>Alnus </it>and its fungal symbionts is a host-dependent speciation (radiation without host change), here observed in <it>Alnicola </it>and <it>Alpova </it>in relation with <it>Alnus </it>subgen. <it>Alnus</it>. Finally host shifts from <it>Alnus </it>subgen. <it>Alnus </it>to <it>A. alnobetula </it>are found in most lineages of <it>Alnicola </it>(at least four times), <it>Alpova </it>(twice) and <it>Lactarius </it>(once), but they do not represent such a common event as could be expected by geographic proximity of trees from the two subgenera. However, active or very recent host extensions clearly occurred in Corsica, where some fungi usually associated with <it>Alnus glutinosa </it>on mainland Europe locally extend there to <it>A. alnobetula </it>subsp. <it>suaveolens </it>without significant genetic or morphological deviation.</p

Facilitation of Balsam Fir by Trembling Aspen in the Boreal Forest: Do Ectomycorrhizal Communities Matter?

Succession is generally well described above-ground in the boreal forest, and several studies have demonstrated the role of interspecific facilitation in tree species establishment. However, the role of mycorrhizal communities for tree establishment and interspecific facilitation, has been little explored. At the ecotone between the mixed boreal forest, dominated by balsam fir and hardwood species, and the boreal forest, dominated by black spruce, several stands of trembling aspen can be found, surrounded by black spruce forest. Regeneration of balsam fir seems to have increased in the recent decades within the boreal forest, and it seems better adapted to grow in trembling aspen stands than in black spruce stands, even when located in similar abiotic conditions. As black spruce stands are also covered by ericaceous shrubs, we investigated if differences in soil fungal communities and ericaceous shrubs abundance could explain the differences observed in balsam fir growth and nutrition. We conducted a study centered on individual saplings to link growth and foliar nutrient concentrations to local vegetation cover, mycorrhization rate, and mycorrhizal communities associated with balsam fir roots. We found that foliar nutrient concentrations and ramification indices (colonization by mycorrhiza per length of root) were greater in trembling aspen stands and were positively correlated to apical and lateral growth of balsam fir saplings. In black spruce stands, the presence of ericaceous shrubs near balsam fir saplings affected ectomycorrhizal communities associated with tree roots which in turn negatively correlated with N foliar concentrations. Our results reveal that fungal communities observed under aspen are drivers of balsam fir early growth and nutrition in boreal forest stands and may facilitate ecotone migration in a context of climate change

Phenetic and genetic structure of tsetse fly populations (Glossina palpalis palpalis) in southern Ivory Coast

Background: Sleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjame University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population? Methods: The amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens. Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassue (186 km north from Abidjan). Results: Neither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassue, showing significant divergence between the two sites. Conclusions: Both markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the "rolling carpet" principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure

R ES EA R CH Open Access Phenetic and genetic structure of tsetse fly populations (Glossina palpalis palpalis) in southern Ivory Coast

Abstract Background: Sleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjamé University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population? Methods: The amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens. Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassué (186 km north from Abidjan). Results: Neither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassué, showing significant divergence between the two sites. Conclusions: Both markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the &quot;rolling carpet&quot; principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure

The Population Structure of Glossina palpalis gambiensis from Island and Continental Locations in Coastal Guinea

Guinea is the country with the highest prevalence of sleeping sickness in West Africa, and we undertook a population genetics analysis there of the most dangerous tsetse fly species of West Africa, Glossina palpalis gambiensis. Our aims were to estimate effective population size and the degree of isolation between coastal sites on the mainland of Guinea (including Dubréka, a highly prevalent sleeping sickness focus) and Loos Islands in order to get the most possible accurate vision of feasibility and sustainability of anti-tsetse strategies of these sites. We found very low migration rates of tsetse between sites except between those situated in the Dubréka area, which seems to contain a widely distributed panmictic tsetse population (i.e. a population where mating occurs at random). Effective population sizes on Loos islands estimated with various techniques all converged to surprisingly small values. These values might be explained by a recent decrease in tsetse numbers on Kassa Island due to bauxite mining activities. But on the other sites, other explanations have to be found, including possible variance in reproductive success. Our genetic results suggest that different control strategies should be advised on the mainland (reduction in tsetse densities, no elimination) compared to the islands (total elimination feasible). This approach could be extended to many areas where vector control of Human and Animal Trypanosomoses is contemplated

Genetic Structure, Linkage Disequilibrium and Signature of Selection in Sorghum: Lessons from Physically Anchored DArT Markers

Population structure, extent of linkage disequilibrium (LD) as well as signatures of selection were investigated in sorghum using a core sample representative of worldwide diversity. A total of 177 accessions were genotyped with 1122 informative physically anchored DArT markers. The properties of DArTs to describe sorghum genetic structure were compared to those of SSRs and of previously published RFLP markers. Model-based (STRUCTURE software) and Neighbor-Joining diversity analyses led to the identification of 6 groups and confirmed previous evolutionary hypotheses. Results were globally consistent between the different marker systems. However, DArTs appeared more robust in terms of data resolution and bayesian group assignment. Whole genome linkage disequilibrium as measured by mean r2 decreased from 0.18 (between 0 to 10 kb) to 0.03 (between 100 kb to 1 Mb), stabilizing at 0.03 after 1 Mb. Effects on LD estimations of sample size and genetic structure were tested using i. random sampling, ii. the Maximum Length SubTree algorithm (MLST), and iii. structure groups. Optimizing population composition by the MLST reduced the biases in small samples and seemed to be an efficient way of selecting samples to make the best use of LD as a genome mapping approach in structured populations. These results also suggested that more than 100,000 markers may be required to perform genome-wide association studies in collections covering worldwide sorghum diversity. Analysis of DArT markers differentiation between the identified genetic groups pointed out outlier loci potentially linked to genes controlling traits of interest, including disease resistance genes for which evidence of selection had already been reported. In addition, evidence of selection near a homologous locus of FAR1 concurred with sorghum phenotypic diversity for sensitivity to photoperiod

Personnalité de la marque : mesure, homogénéité et impact sur la satisfaction. Une application sur le secteur bancaire français

x-hal_journal_id=103841International audienc

Audit de bonnes pratiques d'utilisation des antiseptiques au Centre Hospitalier Lyon Sud (Hospices Civils de Lyon)

LYON1-BU Santé (693882101) / SudocSudocFranceF

Personnalité de la marque : mesure, homogénéité et impact sur la satisfaction. Une application sur le secteur bancaire français

International audienc

Personnalité de la marque : mesure, homogénéité et impact sur la satisfaction. Une application sur le secteur bancaire français

x-hal_journal_id=103841International audienc