Despite its potential impact on soil carbon flow, few studies have attempted to quantify the effects of elevated carbon dioxide (CO2) on production of exudates by mycorrhizal plants. In this study we ...quantified low molecular weight (LMW) organic compounds exuded by non-mycorrhizal (NM) and ectomycorrhizal (ECM) plants in relation to exposure to elevated CO2. Scots pine seedlings, either colonized by one of eight different ECM fungi or non-mycorrhizal (NM), were exposed to either ambient (350 ppm) or elevated (700 ppm) concentrations of CO2. Exudation of LMW organic acids (LMWOAs), amino acids, dissolved monosaccharides and total dissolved organic carbon (DOC) was determined and exudation rates were calculated per g root and fungal dry mass. CO2 had a significant impact on exudation. Under elevated CO2, exudation of total LMWOAs increased by 120-160%, amino acids by 250%, dissolved monosaccharides by 130-270% and DOC by 180-220% compared to ambient CO2 treatment. Net CO2 assimilation rates increased significantly by 41-47% for seedlings exposed to elevated CO2. Exuded C calculated as a percentage of assimilated CO2 increased by 41-88% in the elevated CO2 treatment compared to ambient CO2 treatment.
Ectomycorrhizal interactions established between the root systems of terrestrial plants and hyphae from soil-borne fungi are the most ecologically widespread plant symbioses. The efficient uptake of ...a broad range of nitrogen (N) compounds by the fungal symbiont and their further transfer to the host plant is a major feature of this symbiosis. Nevertheless, we far from understand which N form is preferentially transferred and what are the key molecular determinants required for this transfer. Exhaustive in silico analysis of N-compound transporter families were performed within the genome of the ectomycorrhizal model fungus Laccaria bicolor. A broad phylogenetic approach was undertaken for all families and gene regulation was investigated using whole-genome expression arrays. A repertoire of proteins involved in the transport of N compounds in L. bicolor was established that revealed the presence of at least 128 gene models in the genome of L. bicolor. Phylogenetic comparisons with other basidiomycete genomes highlighted the remarkable expansion of some families. Whole-genome expression arrays indicate that 92% of these gene models showed detectable transcript levels. This work represents a major advance in the establishment of a transportome blueprint at a symbiotic interface, which will guide future experiments.
The leafless, circumboreal orchid Corallorhiza trifida is often assumed to be fully myco-heterotrophic despite contrary evidence concerning its ability to photosynthesize. Here, its level of ...myco-heterotrophy is assessed by analysing the natural abundance of the stable nitrogen and carbon isotopes ¹⁵N and ¹³C, respectively. The mycorrhizal associates and chlorophyll contents of C. trifida were investigated and the C and N isotope signatures of nine C. trifida individuals from Central Europe were compared with those of neighbouring obligate autotrophic and myco-heterotrophic reference plants. The results show that C. trifida only gains c. 52 ± 5% of its total nitrogen and 77 ± 10% of the carbon derived from fungi even though it has been shown to specialize on one specific complex of ectomycorrhizal fungi similar to fully myco-heterotrophic orchids. Concurrently, compared with other Corallorhiza species, C. trifida contains a remarkable amount of chlorophyll. Since C. trifida is able to supply significant proportions of its nitrogen and carbon demands through the same processes as autotrophic plants, this species should be referred to as partially myco-heterotrophic.
Un alto porcentaje de mortalidad se presenta en plántulas de pinos que son trasplantados de vivero a campo, debido a que no poseen hongos ectomicorrízicos los cuales forman simbiosis obligada con las ...plantas de forma natural en los bosques. Estos hongos facilitan la absorción de nutrientes y agua, además de estimular su crecimiento. Debido a la importancia ecológica y fisiológica de los hongos ectomicorrízicos, el presente trabajo evaluó el efecto en crecimiento, peso seco, porcentaje de colonización y contenido de nutrientes de la inoculación de seis especies ectomicorrízicas comestibles de los géneros Lacearía y Hebeloma en Pinus patula Schiede ex Schltdl. & Cham. y P. pseudostrobus Lindl., en condiciones de invernadero. Después de 397 días de la siembra se observó un efecto benéfico en el crecimiento de ambos pinos como resultado de la inoculación en términos de peso seco en parte aérea y radical, así como un mayor contenido de N, P y K. El porcentaje de micorrización en plantas inoculadas con las especies fúngicas varió de 57 % a 90 %. Cuando se efectuó inoculación combinada de especies ectomicorrízicas, se registró dominancia de una de las especies inoculadas, en términos de colonización radical. En estos tratamientos con inoculación simultánea, los efectos benéficos registrados en los hospederos fueron comparables a los observados cuando se inoculó de manera individual a las especies fúngicas dominantes. En función de los resultados encontrados se recomienda en el establecimiento de plantaciones forestales la inoculación de ambas especies de pinos con especies de hongos de los géneros Laccaria y Hebeloma.A high percentage of mortality appears in pine seedlings transplanted from nursery to field, due to the fact that they lack ectomycorrhizal fungi which form obligated symbiosis with plants in natural conditions in the forests. These fungi facilitate the absorption of nutrients and water, and therefore stimulate their growth. Due to the ecological and physiological importance of the ectomycorrhizal fungi, this work evaluated the effect in terms of growth, dry weight, percentage of colonization and nutrient content as a result of the inoculation with six edible ectomycorrhizal fungi within the genera Laccaria and Hebeloma on Pinus patula Schiede ex Schltdl. & Cham. and P.pseudostrobus Lindl. under greenhouse conditions. 397 days after sowing, it was observed a beneficial effect in terms of growth and dry weight of aerial and radical parts, as well as a higher contents of N, P and K of both pines as a result of the inoculation. The percentage of mycorrhization in plants inoculated with the fungi species ranged from 57 % to 90 %. When combined inoculation of ectomycorrhizal species was carried out, dominance of one of the inoculated species, in terms of root colonization, was observed. In these treatments with simultaneous inoculation, the beneficial effects reported in the hosts were comparable with those observed in plants inoculated exclusively with the dominant fungal species. According to the results, the inoculation of P. patula and P. pseudostrobus with fungal species of the genera Laccaria and Hebeloma is recommended in the establishment of forest plantations.
By the comparison of sequences of rDNA-ITS (internal transcribed spacer) region and SSR (simple sequence repeat) loci from 45 isolates of Rhizopogon roseolus, the five specific primer sets, one ...rDNA-ITS primer and four SSR primers, were designed for detection of R. roseolus. All these primer sets amplified the specific PCR products for the total DNAs from mycelia of 45 R. roseolus isolates, respectively, but no amplified product was detected for the DNAs from host plant (Pinus thunbergii) and 16 ectomycorrhizal isolates consist of 13 species including two Rhizopogon species, R. luteolus and R. superiorensis. Furthermore, target regions of these primer sets were also specifically amplified using by DNA templates from ectomycorrhizas of this fungus. Thus, the five sets of primer pair represent a potent tool for the monitoring of introduced isolates of R. roseolus and for molecular ecology applications.
is a pioneer ectomycorrhizal fungus with facultative saprophytic capacities. Here, we sequenced the genome of
strain Sb_GMNB300, which is estimated at 51.6 Mb in size with 872 assembled contigs ...accounting for 12,597 predicted coding genes. This genome will be useful for comparative studies of Pezizales ectomycorrhizal symbioses.
The success of dispersal events depend on the organism’s ability to reach and establish in a new habitat. In symbiotic organisms, establishment also depends on the presence of their symbiont partner ...in the new habitat. For instance, the establishment of obligate ectomycorrhizal (EM) trees outside the forest is largely limited by the presence of EM fungi in soil. Wild boars (
Sus scrofa
) are important dispersal agents of EM fungal spores, particularly in the moderately dry Mediterranean region. The aim of this study was to explore how EM fungal spores dispersed by wild boars influence the EM fungal community associated with the roots of
Pinus halepensis
seedlings at different habitat types. Using a greenhouse bioassay, we grew pine seedlings in two soil types: old-field and forest soils mixed with either natural or autoclaved wild boar feces. In both soils, we observed a community dominated by a few EM fungal species.
Geopora
(85 %) and
Suillus
(68 %) species dominated the forest and old-field soils, respectively. The addition of natural wild boar feces increased the abundance of
Tuber
species in both EM fungal communities. However, this effect was more pronounced in pots with old-field soil, leading to a more even community, equally dominated by both
Tuber
and
Suillus
species. In forest soil,
Geopora
maintained dominance, but decreased in abundance (67 %), due to the addition of
Tuber
species. Our findings indicate that wild boar feces can be an important source for EM inoculum, especially in habitats poor in EM fungi such as old-fields.
• Fungal strains of the 'Hymenoscyphus ericae aggregate' (Helotiales, Ascomycota) were tested for their ability to form ecto-(ECM) and ericoid (ERM) mycorrhizas. • Twelve fungal test isolates were ...inoculated in vitro onto sterile ectomycorrhizal and ericoid host plants. • Five isolates of ectomycorrhizal origin formed ECM, three isolates of ericoid origin formed ERM, but none of the tested isolates was able to form both ECM and ERM. Confirmed ectomycorrhizal strains formed the characteristic black-and-hyaline mantles of the Piceirhiza bicolorata morphotype. This morphology represented an intermediate stage, where mantle-colour changed from light brown to black. The progressive darkening appeared to result from a gradual acropetal melanization of the outer mantle layer. • The synthesis results confirm that the ability to form both ecto- and ericoid mycorrhizal symbioses has evolved within the H. ericae aggregate. In addition, a phylogeny based on ITS1-5.8S-ITS2 rDNA sequences showed that the aggregate includes the ect(endo)mycorrhizal dark septate fungus Phialophora finlandia, grouping with four of the ECM-forming strains. The H. ericae aggregate therefore contains a number of closely related taxa with wide ecological attributes.
PDF
