Evidence of introduced honeybees (Apis mellifera) as pollen wasters in orchid pollination.

Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees (Apis mellifera) on orchid pollination, followed by a study case on Australian orchids.

Mimicking orchids lure bees from afar with exaggerated ultraviolet signals.

Flowers have many traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well-known for attracting bees at close proximity (e.g., <1 m).

Auditing data resolves systemic errors in databases and confirms mycorrhizal trait consistency for most genera and families of flowering plants.

Nearly 150 years of research has accumulated large amounts of data on mycorrhizal association types in plants. However, this important resource includes unreliable allocated traits for some species. An audit of six commonly used data sources revealed a high degree of consistency in the mycorrhizal status of most species, genera and families of vascular plants, but there were some records that contradict the majority of other data (~ 10% of data overall).

FungalRoot: global online database of plant mycorrhizal associations.

Testing of ecological, biogeographical and phylogenetic hypotheses of mycorrhizal traits requires a comprehensive reference dataset about plant mycorrhizal associations. Here we present a database, FungalRoot, which summarizes publicly available data about vascular plant mycorrhizal type and intensity of root colonization by mycorrhizal fungi, accompanied with rich metadata. We compiled and digitized data about plant mycorrhizal colonization in nine widespread languages.

Global mycorrhizal plant distribution linked to terrestrial carbon stocks.

Vegetation impacts on ecosystem functioning are mediated by mycorrhizas, plant-fungal associations formed by most plant species. Ecosystems dominated by distinct mycorrhizal types differ strongly in their biogeochemistry. Quantitative analyses of mycorrhizal impacts on ecosystem functioning are hindered by the scarcity of information on mycorrhizal distributions.

Misdiagnosis of mycorrhizas and inappropriate recycling of data can lead to false conclusions.

We draw attention to a worrying trend for the uncritical use of 'recycled' mycorrhizal data to compile host species lists that include obvious errors or undertake risky analyses that correlate mycorrhizal colonisation levels with environmental or physiological factors despite inherent limitations in datasets. We are not suggesting that all meta-studies are wrong, only that more care should be taken to resolve what can safely be done with recycled mycorrhizal data in the future. We also recommend that mycorrhizal species lists should be checked against standard references since the majority of EM hosts and NM plant belong to families that are well resolved.

Evolutionary history of mycorrhizal symbioses and global host plant diversity.

Contents Summary 1108 I. Introduction 1108 II. Mycorrhizal plant diversity at global and local scales 1108 III.

High-resolution secondary ion mass spectrometry analysis of carbon dynamics in mycorrhizas formed by an obligately myco-heterotrophic orchid.

Mycorrhiza formation represents a significant carbon (C) acquisition alternative for orchid species, particularly those that remain achlorophyllous through all life stages. As it is known that orchid mycorrhizas facilitate nutrient transfer (most notably of C), it has not been resolved if C transfer occurs only after lysis of mycorrhizal structures (fungal pelotons) or also across the mycorrhizal interface of pre-lysed pelotons. We used high-resolution secondary ion mass spectrometry (nanoSIMS) and labelling with enriched (13) CO2 to trace C transfers, at subcellular scale, across mycorrhizal interfaces formed by Rhizanthella gardneri, an achlorphyllous orchid.

Limited carbon and mineral nutrient gain from mycorrhizal fungi by adult Australian orchids.

Premise Of The Study: In addition to autotrophic and fully mycoheterotrophic representatives, the orchid family comprises species that at maturity obtain C and N partially from fungal sources. These partial mycoheterotrophs are often associated with fungi that simultaneously form ectomycorrhizas with trees. This study investigates mycorrhizal nutrition for orchids from the southwestern Australian biodiversity hotspot.

Rampant gene loss in the underground orchid Rhizanthella gardneri highlights evolutionary constraints on plastid genomes.

Since the endosymbiotic origin of chloroplasts from cyanobacteria 2 billion years ago, the evolution of plastids has been characterized by massive loss of genes. Most plants and algae depend on photosynthesis for energy and have retained ∼110 genes in their chloroplast genome that encode components of the gene expression machinery and subunits of the photosystems. However, nonphotosynthetic parasitic plants have retained a reduced plastid genome, showing that plastids have other essential functions besides photosynthesis.

Carbon and nitrogen supply to the underground orchid, Rhizanthella gardneri.

*Rhizanthella gardneri is a rare and fully subterranean orchid that is presumably obligately mycoheterotrophic. R. gardneri is thought to be linked via a common mycorrhizal fungus to co-occurring autotrophic shrubs, but there is no experimental evidence to support this supposition.

Identity and specificity of the fungi forming mycorrhizas with the rare mycoheterotrophic orchid Rhizanthella gardneri.

Fully subterranean Rhizanthella gardneri (Orchidaceae) is obligately mycoheterotrophic meaning it is nutritionally dependent on the fungus it forms mycorrhizas with. Furthermore, R. gardneri purportedly participates in a nutrient sharing tripartite relationship where its mycorrhizal fungus simultaneously forms ectomycorrhizas with species of Melaleuca uncinata s.

Diversity of mycorrhizal fungi of terrestrial orchids: compatibility webs, brief encounters, lasting relationships and alien invasions.

The diversity of mycorrhizal fungi associated with an introduced weed-like South African orchid (Disa bracteata) and a disturbance-intolerant, widespread, native West Australian orchid (Pyrorchis nigricans) were compared by molecular identification of the fungi isolated from single pelotons. Molecular identification revealed both orchids were associated with fungi from diverse groups in the Rhizoctonia complex with worldwide distribution. Symbiotic germination assays confirmed the majority of fungi isolated from pelotons were mycorrhizal and a factorial experiment uncovered complex webs of compatibility between six terrestrial orchids and 12 fungi from Australia and South Africa.

Diversity and classification of mycorrhizal associations.

Most mycorrhizas are 'balanced' mutualistic associations in which the fungus and plant exchange commodities required for their growth and survival. Myco-heterotrophic plants have 'exploitative' mycorrhizas where transfer processes apparently benefit only plants. Exploitative associations are symbiotic (in the broad sense), but are not mutualistic.

Development of in situ and ex situ seed baiting techniques to detect mycorrhizal fungi from terrestrial orchid habitats.

An innovative ex situ fungal baiting method using soil collected from field sites which allows the simultaneous detection of mycorrhizal fungi for multiple terrestrial orchids is presented. This method demonstrated that coarse organic matter (> 2 mm) in the litter and topsoil was the most important reservoir of inoculum of these fungi. A new in situ seed baiting method using multi-chambered packets to simultaneously assess germination for different orchid species within soil is also introduced.

Coevolution of roots and mycorrhizas of land plants.

Here, the coevolution of mycorrhizal fungi and roots is assessed in the light of evidence now available, from palaeobotanical and morphological studies and the analysis of DNA-based phylogenies. The first bryophyte-like land plants, in the early Devonian (400 million years ago), had endophytic associations resembling vesicular-arbuscular mycorrhizas (VAM) even before roots evolved. Mycorrhizal evolution would have progressed from endophytic hyphae towards balanced associations where partners were interdependent due to the exchange of limiting energy and nutrient resources.

Mycorrhizal fungus propagules in the jarrah forest: II. Spatial variability in inoculum levels.

Spatial variations in the capacity of propagules of arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi to form associations in their natural habitats were investigated using bioassays with bait plants grown in intact cores of forest soil. These cores were collected from a sclerophyllous forest community dominated by Eucalyptus marginata Donn ex Smith (jarrah) and E. calophylla Lindley (marri) trees with a diverse shrub understorey in the mediterranean (winter rainfall) climatic zone of Western Australia.

The roots and mycorrhizas of herbaceous woodland plants: I. Quantitative aspects of morphology.

The time-course of development of the roots and endomycorrhizas of five common herbaceous plants in a southern Ontario hardwood forest (Arisaema atrorubens, Erythronium americanum, Asarum canadense, Smilacina racemosa, and Trillium grandiflorum) was examined. Root growth of these species was very slow. Formation of vesicular-arbuscular (VA) mycorrhizas was quantified by measuring the average distance from growing root tips at which (i) hyphal contact, (ii) root penetration, and (iii) arbuscule formation by hyphae of VA mycorrhizal fungi first occurred.

The roots and mycorrhizas of herbaceous woodland plants: II. Structural aspects of morphology.

The morphology of vesicular-arbuscular (VA) mycorrhizas in the roots of five species of herbaceous woodland plants, in which root growth and mycorrhiza formation were quantified in the first part of this study was examined. The root anatomy of these species was also examined in detail, using various staining procedures to observe cell wall structure, especially in the region where mycorrhizal colonization was initiated. The morphology of mycorrhizal colonies within the roots of these species was observed at different stages of development using light microscopy.