Phylogenetic classification of Cordyceps and the clavicipitaceous fungi

Orchid mycorrhizas are mutualistic interactions between fungi and members of the Orchidaceae, the world’s largest plant family. The majority of the world’s orchids are photosynthetic, a small number of species are myco-heterotrophic throughout their lifetime, and recent research indicates a third mode (mixotrophy) whereby green orchids supplement their photosynthetically fixed carbon with carbon derived from their mycorrhizal fungus. Molecular identification studies of orchid-associated fungi indicate a wide range of fungi might be orchid mycobionts, show common fungal taxa across the globe and support the view that some orchids have specific fungal interactions. Confirmation of mycorrhizal status requires isolation of the fungi and restoration of functional mycorrhizas. New methods may now be used to store orchid-associated fungi and store and germinate seed, leading to more efficient culture of orchid species. However, many orchid mycorrhizas must be synthesised before conservation of these associations can be attempted in the field. Further gene expression studies of orchid mycorrhizas are needed to better understand the establishment and maintenance of the interaction. These data will add to efforts to conserve this diverse and valuable association.

/pdf/further-advances-in-orchid-mycorrhizal-research-ibqr3edqjc.pdf

Further advances in orchid mycorrhizal research

Summary 1 Schedules of survival, growth and reproduction are key life-history traits Data on how these traits vary among species and populations are fundamental to our understanding of the ecological conditions that have shaped plant evolution Because these demographic schedules determine population

/pdf/the-compadre-plant-matrix-database-an-open-online-repository-1rcxi8diry.pdf

The compadre Plant Matrix Database: an open online repository for plant demography

Germination and seedling establishment in orchids: a complex of requirements

� Background Seedling recruitment is essential to the sustainability of any plant population. Due to the minute nature of seeds and early-stage seedlings, orchid germination in situ was for a long time practically impossible to observe, creating an obstacle towards understanding seedling site requirements and fluctuations in orchid populations. The introduction of seed packet techniques for sowing and retrieval in natural sites has brought with it important insights, but many aspects of orchid seed and germination biology remain largely unexplored. � Key Considerations The germination niche for orchids is extremely complex, because it is defined by requirements not only for seed lodging and germination, but also for presence of a fungal host and its substrate. A mycobiont that the seedling can parasitize is considered an essential element, and a great diversity of Basidiomycota and Ascomycota have now been identified for their role in orchid seed germination, with fungi identifiable as imperfect Rhizoctonia species predominating. Specificity patterns vary from orchid species employing a single fungal lineage to species associating individually with a limited selection of distantly related fungi. A suitable organic carbon source for the mycobiont constitutes another key requirement. Orchid germination also relies on factors that generally influence the success of plant seeds, both abiotic, such as light/shade, moisture, substrate chemistry and texture, and biotic, such as competitors and antagonists. Complexity is furthermore increased when these factors influence seeds/seedling, fungi and fungal substrate differentially. � Conclusions A better understanding of germination and seedling establishment is needed for conservation of orchid populations. Due to the obligate association with a mycobiont, the germination niches in orchid species are extremely complex and varied. Microsites suitable for germination can be small and transient, and direct observation is difficult. An experimental approach using several levels of environmental manipulation/control is recommended.

VIEWPOINT: PART OF A HIGHLIGHT ON ORCHID BIOLOGY Germination and seedling establishment in orchids: a complex of requirements

The 70% decline of the Federally threatened eastern prairie fringed orchid, Platanthera leucophaea (Nuttall) Lindley, has prompted concern for its recovery through artificial propagation. We describe a technique to germinate seeds and cultivate seedlings of P. leucophaea in vitro using cold treatments (=stratification) and mycorrhizal fungi (=symbiotic seed germination). Five fungal isolates were recovered from mature P. leucophaea plants in Illinois and Michigan and were identified as members of the anamorphic genus Ceratorhiza Moore. Stratified seeds inoculated with mycorrhizal fungi germinated within 25 d of sowing. Leaf-bearing seedlings were obtained by chilling young seedlings (protocorms) for 107 d. Our successful culture of leaf-bearing seedlings with a presumed mycotrophic capability may make it possible for this threatened orchid to be propagated in soil ex vitro, followed by reintroduction into suitable habitats.

https://bioone.org/journals/The-American-Midland-Naturalist/volume-145/issue-1/0003-0031(2001)145[0168:MFACAS]2.0.CO;2/Mycorrhizal-Fungi-and-Cold-assisted-Symbiotic-Germination-of-the-Federally/10.1674/0003-0031(2001)145[0168:MFACAS]2.0.CO;2.pdf

Mycorrhizal Fungi and Cold-assisted Symbiotic Germination of the Federally Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nuttall) Lindley

Protocorm mycobionts of the Federally threatened eastern prairie fringed orchid, Platanthera leucophaea (Nutt.) Lindley, and a technique to prompt leaf elongation in seedlings

Crossing effects on seed viability and experimental germination of the federal threatened Platanthera leucophaea (Orchidaceae)

The Federal threatened eastern prairie fringed orchid (Platanthera leucophaea) occupies prairies, sedge meadows, bogs and fens, primarily north of the Wisconsinan glacial boundary. In the Midwest, where restoration is a recovery objective, its southern distribution is thought to be limited by the transition from nutrient-rich Wisconsinan-aged soils to more acidic nutrient poor soils of Illinoian-aged glacial drift. To better understand edaphic factors affecting its distribution and potential for establishment of new populations, we analyzed soil characteristics across the range of habitats occupied by this species, as well as from unoccupied habitats on the Illinoian Till Plain. We found that P. leucophaea occupies a complex edaphic gradient in variation of % organic matter, base content and soil texture. On Wisconsinan-aged substrates, it occurs in circum-neutral base-rich organic prairie soils in Illinois and Wisconsin and in less calcareous soils with slightly higher pH and lower organic matter content in Michigan lake plain prairies. Eastern sand prairie and sedge meadow habitats on Wisconsinan-aged drift and on unglaciated soils are moderately acid and nutrient poor, while bog and fen habitats are more strongly acidic and highly organic, with no evidence for an underlying calcareous substrate. In comparison, unoccupied prairie soils on the Illinoian till plain have lower pH, % organic matter and base concentrations. These soils also have relatively high % silt content which results in comparatively low available soil moisture holding capacity. This combination of soil conditions may exceed the tolerance limits of P. leucophaea and prevent this species from occurring south of the Wisconsin glacial boundary in the Midwest. On the other extreme, calcareous fens have high pH levels as well as extremely high calcium concentrations, which may exceed the tolerance limits of this species. These findings have implications for guiding efforts to establish P. leucophaea into habitats that should be suitable for this species.

Relationships Between Soil Characteristics, Distribution and Restoration Potential of The Federal Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nutt.) Lindl

Marlin L. Bowles

Papers

Mycorrhizal Fungi and Cold-assisted Symbiotic Germination of the Federally Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nuttall) Lindley

Protocorm mycobionts of the Federally threatened eastern prairie fringed orchid, Platanthera leucophaea (Nutt.) Lindley, and a technique to prompt leaf elongation in seedlings

Crossing effects on seed viability and experimental germination of the federal threatened Platanthera leucophaea (Orchidaceae)

Relationships Between Soil Characteristics, Distribution and Restoration Potential of The Federal Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nutt.) Lindl

Recovery planning and reintroduction of the Federally threatened Pitcher's thistle ( Cirsium pitcheri ) in Illinois