The Influence of Inoculated and Native Ectomycorrhizal Fungi on Morphology, Physiology and Survival of American Chestnut

The objective of this study was to evaluate the influence of five different species of ectomycorrhizal (ECM) fungi on root colonization of native fungi on putatively blight resistant chestnut hybrids (Castanea dentata x C. mollissima) in a reclaimed mine site in central Ohio. The five species were Hebeloma crustuliniforme, Laccaria bicolor, Scleroderma polyrhizum, Amanita rubescens, and Suillus luteus. We used a combination of DNA sequencing of the ITS region and phylogenetic analyses to indentify fungi found on roots after 12 and 18 months in the field. Non-metric multidimensional scaling (NMDS) ordinations were used to determine if ECM community composition was influenced by the fungal inoculum used. The results of this study demonstrated that the selected ECM species do not persist on chestnut after one year in the field. In addition, these selected ECM species did not impede natural root colonization of native fungi or influence ECM community composition after two growing seasons. Although these species did not persist in the field, the presence of ECM inoculum (with the exception of Amanita) greatly contributed to the survival of hybrid chestnut seedlings. Therefore, introduced inoculum that was present in the very early stages of outplanting had persisting effects with regard to seedling establishment in the field, even if the original inoculum did not persist. ECM fungi native to the area colonized chestnuts resulting in increased growth rates. These native assemblages may contain species better able to form functional mycorrhizas under these environmental extremes. Therefore, the conservation of these species may be necessary to facilitate long-term survival of deciduous tree species historically native to these lands

Facilitation of American Chestnut (Castanea dentata) Seedling Establishment by Pinus virginiana in Mine Restoration

This study evaluated the influence of planting sites on the establishment and ectomycorrhizal (ECM) colonization of American chestnut (Castanea denetata (Marsh.) Borkh.) on an abandoned coal mine in an Appalachian region of the United States. Root morphotyping and sequencing of the fungal internal transcribed spacer (ITS) region were used to identify the ECM species associated with the chestnut seedlings. Germination, survival, ECM root colonization, and growth were assessed in three habitats: forest edge, center (plots without vegetation), and pine plots (a 10-year-old planting of Pinus virginiana). Seedlings in pine plots had higher survival (38%) than the other plot types (center 9% and forest edge 5%; P = 0.007 ). Chestnuts found colonized by ECM within the pine plots were larger (P = 0.02), contributed by a larger root system (P = 0.03). Forest edge and pine plots had more ECM roots than seedlings in center plots (P = 0.04). ITS fungal sequences and morphotypes found among chestnut and pine matched Scleroderma, Thelephora, and Pisolithus suggesting these two plant species shared ECM symbionts. Results indicated that the presence of P. virginiana had a greater facilitative effect on growth and survival of chestnut seedlings

The Efficiency of Introduced Pisolithus tinctorius on Backcrossed Chestnut Germination and Survival.

American chestnut was eliminated as a canopy tree from the Appalachian region of North America with the introduction of chestnut blight in the early 1900s. Breeding programs initiated in the 1980s have produced seedling lines that display the pure American morphology with potential resistance to chestnut blight. More work is required to assess their field performance in field sites representative of their native range. This study used American (Castanea dentata) and backcrossed hybrid chestnuts (C. dentata × C. mollissima) on an abandoned coal mine in southeastern Ohio. Half of the seeds were planted with ectomycorrhizal fungus (ECM) Pisolithus tinctorius (Pt) as a granular inoculum. Germination, survival, percent ECM colonization, and ECM community were assessed. In addition, soil data such as pH, cation exchange capacity, nutrients, texture, temperature, moisture, and organic matter were evaluated to determine their influence on ECM. After the first and second growing season, germination and survival were not influenced by the Pt inoculum or chestnut genotypes. In addition, ECM root colonization, fungal community composition, and host response were similar between seedling types, regardless of the inoculum added. This indicated: 1) backcrossed breeding produces seedlings similar to pure American chestnuts with regard to growth, establishment, and fungal symbionts, and 2) the granular inoculum had no influence on ECM colonization in this field site. Introducing spore inoculum to a field site greatly deficient in nutrients and organic matter is not an efficient method to ensure ECM symbiosis. However, natural colonization by native ECM fungi, though limited, did result in larger chestnut seedlings. Cation exchange capacity significantly contributed to the percent of root colonization of ECM fungi on chestnut. Determination of planting protocols and factors that influence ECM root colonization will be useful for in future mine restoration projects using backcrossed American chestnut as a restoration tree

American Chestnut\u27s Role in the Ecological Restoration of Coal-Mined Landscapes

The American chestnut’s fast growth rate, early nut production, and quality of timber make it a valuable tree for use in coal mine restoration projects (Figure 1). This species tolerates a wide range of ecological conditions, including dry soils and low pH, which are typical of some sites previously mined for coal. Experimental planting methods are currently being studied to determine protocols most conducive for establishing chestnut trees on these sites. The Forestry Reclamation Approach (FRA) proposed by the Appalachian Regional Reforestation Initiative (ARRI) recommends the selection of proper soil substrate, a deep rooting zone, appropriate herbaceous vegetation, and the proper planting of ecologically valuable trees (Zipper et al. 2011). The premise is that established trees, like chestnut, can accelerate native forest recovery by adding organic matter to the soil, attracting seed- carrying wildlife, and providing reservoirs for beneficial soil microorganisms. Coupling FRA planting protocols with the goals of The American Chestnut Foundation’s (TACF) restoration program accomplishes two objectives. For one, this partnership introduces a valuable native tree for the restoration of Appalachian landscapes impacted by mining. Second, large-scale ecological restoration projects provide an opportunity for the directed experimental plantings of various chestnut seed lines. The ultimate goal is the successful establishment of founder populations of chestnut that can potentially produce blight-resistant offspring that migrate into surrounding forests (Jacobs 2007). This paper summarizes a portion of a long-term study in southeastern Ohio that is evaluating FRA soil ripping as a preparation method for the planting of pure American and backcrossed chestnut lines (B1-F3 and B2-F3) on a reclaimed coal mine site. Growth and survival of the different chestnut seed lines and the presence of chestnut blight cankers are repor

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

Deux cas de kyste papillaire hématique de l'ovaire

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Résection intestinale pour tumeur diffuse du petit bassin; anus hypogastrique; quatre ans après, ablation du rectum et suture du côlon transverse à l'anus; guérison

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Communication de M. Keiffer. A propos de quelques malformations congénitales

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Rupture au moment du travail d'un ancienne cicatrice de césarienne; coeliotomie; l'oeuf complet est dans l'abdomen; hystérectomie; guérison

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