A test of the mycorrhizal-associated nutrient economy framework in two types of tropical rainforests under nutrient enrichments

Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), and tested it using nutrient addition experiments conducted in two tropical rainforests. We selected two tropical rainforests dominated by arbuscular mycorrhizal(AM) and ectomycorrhizal(ECM) trees, and established eighteen20 m×20 m plots in each rainforest. Six nitrogen(N) and phosphorus(P) addition treatments were randomly distributed in each rainforest with three replicates. We examined the differences in soil carbon(C) and nutrient cycling, plant and litter productivity between the two rainforests and their responses to 10-year inorganic N and P additions. We also quantified the P pools of plants, roots, litter, soil and microbes in the two rainforests. Overall,distinct MANE frameworks were applicable for tropical rainforests, in which soil C, N and P were cycled primarily in an inorganic form in the AM-dominated rainforest, whereas they were cycled in an organic form in the ECMdominated rainforest. Notably, the effects of mycorrhizal types on soil P cycling were stronger than those on C and N cycling. The intensified N and P deposition benefited the growth of AM-dominated rainforests instead of ECMdominated rainforests. Our findings underpin the key role of mycorrhizal types in regulating biogeochemical processes, and have important implications for predicting the ecological consequences of global changes.

Single and combined eff ects of fertilization,ectomycorrhizal inoculation,and drought on container-grown Japanese larch seedlings

Climate change can intensify drought in many regions of the world and lead to more frequent drought events or altered cycles of soil water status.Therefore,it is important to enhance the tolerance to drought and thus health,vigor,and success of transplantation seedlings used in the forestry by modifying fertilization and promoting mycorrhization.Here,we sowed seeds of Japanese larch(Larix kaempferi)in 0.2-L containers with 0.5 g(low fertilization;LF)or 2 g(high fertilization;HF)of slow-release fertilizer early in the growing season.One month later,we irrigated seedlings with non-sterilized ectomycorrhizal inoculum(ECM)or sterilized solution(non-ECM),and after about 2 months,plants were either kept well watered(WW;500 mL water/plant/week)or subjected to drought(DR;50 mL water per plant/week)until the end of the growing season.HF largely stimulated plant growth and above-and belowground biomass production,eff ects that are of practical signifi cance,but caused a small decrease in stomatal conductance(Gs 390)and transpiration rate(E 390),which in practice is insignifi cant.ECM treatment resulted in moderate inhibition of seedling growth and biomass and largely canceled out the enhancement of biomass and foliar K content by HF.DR caused a large decrease in CO 2 assimilation,and enhanced stomatal closure and induced senescence.DR also largely depleted foliar Mg and enriched foliar K.Although DR caused a large decrease in foliar P content in LF,it moderately increased P in HF.Likewise,DR increased foliar K in HF but not in LF,and decreased foliar P in ECM plants but not in non-ECM plants.Conversely,ECM plants exhibited a large enrichment in foliar P under WW and had a lower water potential under DR when grown in LF.These results indicate that the drought tolerance and health and vigor of Japanese larch seedlings can be modifi ed by soil fertility and soil microorganisms.This study provides a basis for new multifactorial research programs aimed at producing seedlings of superior quality for forestation under climate change.

Ectomycorrhizal diversity at five different tree species in forests of the Taunus Mountains in Central Germany

Ectomycorrhizal fungi were investigated on five different forest tree species growing in pure stands on the south slope of the Taunus Mountains, which are situated at the northern end of the Rhine rift valley in Central Germany. Mycorrhizal fungi accompanying the genus Xerocomus were identified and their frequencies counted. Using ITS markers, 22 different fungal species were identified down to species level and 6 down to genus level. On European beech (Fagus sylvatica) 16 fungal species and 4 genera were identified and on Sessile oak (Quercus petraea) 16 ectomycorrhizal species and 2 genera were determined. On both deciduous trees we observed exclusively: Cortinarius subsertipes, Genea hispidula, Lactarius quietus, Tylopilus felleus and a Melanogaster genus. On Norway spruce (Picea abies) we identified 13 different mycorrhizal species and 3 different genera, on Silver fir (Abies alba) 12 species and 3 genera, and in association with European larch (Larix decidua) 11 species and 3 genera. On these conifers Cortinarius anomalus, Lactarius necator and a Piloderma genus occurred exclusively. Comparisons with published data of ectomycorrhizal diversity on the same five tree species, growing in different areas of Germany and Europe, led to the conclusion that there is relative site specificity for ectomycorrhizal communities. Upper soil compartments of the stands investigated in the Taunus Mountainssuffer from soil acidification (pH-H20 ~3.7 to ~4.8). However, a clear correlation between upper soil pH-values and fungal diversity was not observed. On the other hand, nitrate concentrations in upper soil compartments (~26 to ~91 kgNO3-/ha) were higher in older stands as compared to younger ones. Higher nitrate concentrations in upper soils correlated with lower numbers of mycorrhizal individuals.

Poor-Soil Rhizosphere Enriched with Different Microbial Activities Influence the Availability of Base Elements

Understanding the ecology of soil rhizosphere is essential to enhancing soil ecosystem and plants productivity. Poor-soil properties can limit rhizosphere microbial composition, interactions and plants productivity. Furthermore, the presence of plant exudates and microbial interation can change the rhizosphere dynamic. In the current study, we used two types of soils, rich nutrient soil represented by potting-soil and poor-soil represented with nutrient-deprived poor-soil. The two types of soil were inoculated with five microbial combinations using plant growth promoting bacteria (PGPB, Pseudomonas fluorescens) and mycorrhiza, and planted with two-day-old sorghum bicolor and Setaria italica (Foxtail millet) seedlings. Soil elements analyses were conducted 60 days after planting. The availability of exchangeable base alkali elements (Ca, Mg, Na) were measured and compared. Na was exclusively affected by PGPB inoculation in both soil types. Ca and Mg increased highest when associated with arbuscular inoculation, exclusively, in comparison to association with PGPB or Ectomycorrhiza in both soil types when planted with sorghum. Whereas, the same elements Ca and Mg, increased highest when associated with arbuscular mycorrhiza inoculation whether combined with PGPB or ectomycorrhiza when in soil planted with Setaria italica. The mycorrhiza increased Ca and Mg availability when combined with PGPB. Naincrease was associated only with PGPB inoculation solely in both soil types. The use of arbuscular mycorrhiza inoculation combined with PGPB is ecofriendly method to enrich rhizosphere in poor-soil and eliminate the need to use any chemical fertilizers.

The full length <i>PtSRP</i>(<i>Pisolithus tinctorius</i>symbiosis related protein) fungal mRNA encodes a potential marker of ectomycorrhiza formation

The Pisolithus tinctorius symbiosis related protein expressed sequence tag (EST PtSRP) was previously identified in the first hours of the interaction between the fungus Pisolithus tinctorius and sweet chestnut Castanea sativa, and partially characterized as a fungal marker gene of ectomycorrhizal symbiosis formation. We used the 5’ rapid amplification of cDNA ends (RACE) to obtain the PtSRP mRNA 5’ region, and together with our previously reported 3’ mRNA region, the full mRNA sequence was assembled by use of bioinformatics tools and deposited to GenBank (Accession: GU733439). The full-length mRNA sequence (636 bp) revealed the locations of the 5’ and 3’ untranslated regions (UTRs) and contained the Kozak sequence (ccc aag ATG A) in the 5’ UTR. The in silico translated PtSRP open reading frame (ORF) codes for a 127 amino acid protein and contained four putative post-translational modification sites (two N-glycosylation and two phosphorylation). The protein secondary structure is postulated to be composed of one N-terminal hydrophobic transmembrane alpha helix and at least six hydrophilic beta-strands spread across the protein. Sub-cellular localization prediction suggests that the protein is involved in cellular secretory pathway, supported by the presence of a cleavage site motif close to the membrane anchor. The data presented herein indicate the role of PtSRP as a fungal membrane secreted protein involved in early stages of ectomycorrhizal formation, with application as a possible marker for nascent ectomy-corrhiza fungal development.

Ectomycorrhiza of Larix sibirica Ledeb. along the gradients of main ecological factors and elevation at the Northern and Subpolar Urals

Siberian larch(Larix sibirica Ledeb.) forests cover the largest areas in the Eurasian boreal zone, but there are insufficient data on its root system including the structure and functional traits of ectomycorrhizas(EM). The aim of this research is to find out if the morphological parameters of Larix sibirica EMs responded to the changes in elevation and main ecological factors(soil humidity, soil richness, soil acidity and habitat illumination). Using light microscopy, we studied EM diameter, root diameter, mantle width, and mantle volume share, share of tannin cells layers, EM density and EM length of Larix sibirica in two main types of plant communities along the elevation gradient at the Northern and Subpolar Urals. Differences in the environment were traced using phytoindication approach and the Ellenberg ecological scales. All the studied traits depend on the elevation and studied ecological factors. The diversity of fungal mantles is low, and the proportion of unstructured and pseudoparenchymatous mantles is high in response to the deterioration of the humidity, soil nitrogen content and acidity at higher-altitude habitats. Results of EM quantitative parameters measurements confirmed this pattern. We found a decline in the EM linear dimensions accompanied by a compensatory growth of the EM density with the raised elevation and the deterioration of environmental conditions.

Effects of soil nutrient availability and ozone on container-grown Japanese larch seedlings and role of soil microbes

The interactive eff ects of ozone,soil nutrient availability and root microorganisms on physiological,growth,and productivity traits were studied for the fi rst time for Japanese larch(Larix kaempferi)seedlings grown in containers over a growing season,using a free air ozoneconcentration enrichment exposure system.High nutrient availability altered leaf and root nutrient dynamics and enhanced plant growth;however,it also enhanced seedling susceptibility to damping-off disease compared to low nutrient availability.Negative eff ects of elevated ozone,as compared with ambient ozone,on leaf gas exchange and plant stem form were neither off set nor exacerbated by soil nutrient availability and root colonizers.Such negative eff ects suggest that elevated ozone may have implications for ecological health even when plant vigor is limited by factors other than ozone.Inoculation of roots with ectomycorrhizae had negligible infl uence on the eff ects of either soil nutrient availability or ozone.However,this lack of eff ect may be upon impeded formation of complete mycorrhizal root tips due to factors other than the manipulated variables.B and Na appeared to have an important role in stress responses,so further studies to examine their link with physiological mechanisms as a function of time.This study provides an important perspective for designing forestry practices to enhance seedling health.

A Survey of Mycorrhizal Colonization in the 50-ha Korup Forest Dynamic Plot in Cameroon

A study was carried out in the 50-ha Korup Forest Dynamic Plot in South West Cameroon, to evaluate the diversity of mycorrhizal associations as well as to determine the effect of habitat types on the type of mycorrhizal association. A total of 781 individual trees belonging to 51 families, 165 genera and 252 tree species, were sampled from the four habitat types found in the plot: low drier, hill slope, ridge top and wetland complexes. In each habitat type, all stems ≤ 1 cm depth at breast height had already been tagged, measured, mapped and identified to the species level. Root samples were collected, cleared, stained and examined microscopically for mycorrhizal type. Of the total number of species sampled, 248 (98.41%) formed mycorrhizal associations with only 4 (1.59%) being non mycorrhizal. For mycorrhizal trees, 232 (93.55%) formed exclusively arbuscular mycorrhiza, 10 (4.03%) formed ectomycorrhiza, while 6 (2.42%) formed both ecto- and arbuscular mycorrhiza. The ridge top harbored the least number (152) of mycorrhizal trees while the low drier area harbored the most number (266) of mycorrhizal trees. Although habitat effect was not significant in influencing mycorrhizal colonization of tree species, some tree species did show aggregated patterns in particular habitats.

Scleroderma nastii sp.nov.,a gasteroid mushroom from Phulchoki hill,Nepal

A new species of Scleroderma is described from temperate Oak forest of Phulchoki hill,at the highest peak(2,762 m)ringing the Kathmandu valley,Nepal.Smooth to velvety,pseudostipitate basidiome,smaller and sub-reticulate basidiospores in comparison to its close relatives,are key diagnostic features of this newly discovered mushroom.The novelty of the taxon was also confirmed based on phylogenetic analysis using the data sets of the internal transcribed spacer region(ITS)of nuclear rDNA sequences along with the analysis of scanning electron micrographs of its basidiospores.A comprehensive description,illustrations,and comparisons with phenetically similar species are provided in this study.Additional surveys are needed to verify the species diversity and clarify their geographic distribution.

Growth of Shorea contorta Vid.Inoculated with Eucalypt Ectomycorrhizal Fungi in the Nursery and in a Logged-Over Dipterocarp Forest in Surigao,Philippines

This study was conducted to determine the compatibility of ectomycorrhizal (ECM) fungi associated with eucalypts on dipterocarps. Two nodal cuttings of Shorea contorta (Vid.) were rooted in a non-mist system for two months, and later inoculated with vegetative mycelia of three strains of Pisolithus collected under eucalypts and a strain of Scleroderma from dipterocarps. Inoculated rooted cuttings were planted in irradiated potting mix and raised in the nursery for five months. Root colonization prior to outplanting ranged from 31% to 38% and ECM fungi did not colonize the uninoculated ones. The cuttings were outplanted in a logged-over dipterocarp forest in Bislig, Surigao Sur following a Randomized Complete Block Design with four blocks;each block was planted with 50 seedlings. Two years after outplanting, Pisolithus strain from New Caledonia (H6394) promoted the highest height (46 cm) and diameter (0.48 cm) increment. Height was increased by 17% and diameter by 7% relative to the uninoculated control. By contrast, Pisolithus strain from the Philippines (H615) gave the shortest (26 cm) height increment and smallest (0.42 cm) diameter. Diameter growth of cuttings inoculated with Scleroderma D01 (from the Philippines) and a Pisolithus strain from Australia (H445) was bigger (0.47 cm) than the uninoculated treated cuttings (0.45 cm). In terms of survival, the uninoculated cuttings gave the highest (90%) percent survival while the lowest (60%) was those inoculated with Pisolithus strain from New Caledonia. It is possible that the indigenous ECM fungi infected easily the roots of the uninoculated cuttings thus contributing to the high survival rate (90%). During outplanting, fruit bodies of S. columnare were present in the field site. The results, however, show that ECM fungi were able to colonize the roots and that some strains promoted the growth and survival of S. contorta planted in a logged-over dipterocarp forest in Bislig, Surigao, Philippines.

Ectomycorrhizal fungi associated with Pinus gerardiana in Kinnaur district of Himachal Pradesh,India

Investigations on the diversity of ectomycorrhizal macrofungi associated with Pinus gerardiana in Kinnaur district of Himachal Pradesh revealed the associations of 22 ectomycorrhizal fungi belonging to 12 genera in 11 families.The dominant genus was Geastrum(4 species),followed by Russula and Suillus(3 species each);Boletus,Ramaria and Scleroderma(2 species each)and rest of the genera were represented by one species each.Among these,Scleroderma polyrhizum had the highest frequency of occurrence and was recorded in most of the sites.Maximum diversity was recorded beyond 2500m above mean sea level.Morpho-anatomical study of mycorrhizal roots revealed typical ectomycorrhizal association exhibiting well-developed mantle and hartig net.

Affiliation of Dihydrolipoyl Dehydrogenase Allozymes in Mycorrhizae of European Forest Trees and Characterization of the Enzyme of the Matt Bolete (<i>Xerocomus pruinatus</i>) and the Bay Bolete (<i>X. badius</i>)

Mycorrhizal roots of the deciduous trees European beech (Fagus sylvatica (L.)) and Sessile oak (Quercus petraea (MattuschkaLiebl.)) and the conifers Norway spruce (Picea abies (L.) H. Karst.) and European larch (Larix decidua (Mill.)) associated with the ectomycorrhizal fungi matt bolete (Xerocomus pruinatus (Fries 1835)) or bay bolete (X. badius (Fries 1818)) were analysed with respect to the occurrence of dihydrolipoyl dehydrogenase (EC 1.8.1.4) allozymes. In root tissues of the two deciduous trees, two gene loci could be visualized after cellulose acetate electrophoresis while three loci were expressed in root tissues of the two coniferous species. The two fungal species and further ectomycorrhizal fungi expressed exclusively one dihydrolipoyl dehydrogenase gene. In Xerocomus pruinatus and X. badius, the dihydrolipoyl dehydrogenase gene consists of 1460 bp and 1370 bp, respectively, including five introns each consisting of 52 bp. Their DNA sequences correspond to 70 to 90% to other fungal dihydrolipoyl dehydrogenase genes. One monomer of the dimeric dihydrolipoyl dehydrogenase enzyme consists of 486 (X. pruinatus) or 454 (X. badius) amino acids which sum up to a molecular mass of 55 kDa (X. pruinatus), respectively 52 kDa (X. badius). The number of positively charged amino acid residues makes 79 (X. pruinatus) and 68 (X. badius) and the number of negatively charged amino acid residues was calculated to make 46 (X. pruinatus) and 48 (X. badius);isoelectric points make 9.99 (X. pruinatus) and 9.68 (X. badius). Calculated three dimensional structures reveal a short NADH binding site being part of a larger FAD-binding site and a binding/dimerization domain.

Bioactive potential of the wild edible mushroom Ramaria versatilis

The scrub jungles of the southwestern India support different mushrooms of economic significance.The coral mushrooms belong to the genus Ramaria distributed worldwide and many species are edible,medicinal and ectomycorrhizal.Ramaria versatilis occurring in scrub jungles were analyzed for biochemical profile and antioxidant potential.Qualitative tests of uncooked samples showed presence of saponins,flavonoids,alkaloids,terpenoids and coumarins,whereas the cooked samples possess saponins,alkaloids,terpenoids,cardiac glycosides and coumarins.Quantitative assessment revealed significantly higher quantities of total phenolics as well as vitamin C in uncooked than cooked samples.The total antioxidant activity,ferrous ion-chelation capacity and DPPH radical-scavenging activity were also significantly high in uncooked samples.Occurrence,substrates,mycorrhizal association and edibility of different Ramaria occurring in the Western Ghats region have been reviewed with comparison of nutritional and antioxidant potential of R.versatilis with other Ramaria spp.

A 60-year journey of mycorrhizal research in China:Past,present and future directions

The significance of mycorrhizas(fungal roots in 90% of land plants) in plant nutrient acquisition and growth,element biogeo-chemical cycling and maintaining of terrestrial ecosystem structures has been globally established for more than 120 years.Great progress in mycorrhizal research in the past 60 years(1950-2009,1981-2009 in particular) has also been made across China,particularly in the mainland,Hong Kong and Taiwan.For instance,a total of 20 new and ~120 records of arbuscular mycorrhizal(AM) fungal species,30 new and ~800 records of ectomycorrhizal(EM) fungal species,a dozen of new and ~100 records of orchid mycorrhizal(OM) fungal species have been isolated by morphological observation and/or molecular identification in China since the 1950s.Great accomplishment has also been made in the following area,including fungal species richness and genetic structure,relationships between species composition and plant taxa,effects of mycorrhizal fungi on plant nutrient uptake and growth,resistances to pathogens and interactions with other soil microorganisms,potential of mycorrhizal fungi in phytoremediation and/or land reclamation,alterations of enzymatic activities in mycorrhizal plants,and elevated CO2 and O3 on root colonization and species diversity.Unfortunately,the international community cannot easily appreciate almost all Chinese mycorrhizal studies since the vast majority of them have been published in Chinese and/or in China-based journals.The aim of this review is to make a comprehensive exposure of the past and present China's major mycorrhizal research to the whole world,and then to suggest potential directions for the enhancement of future mycorrhizal research within and/or between the Chinese and international mycorrhizal community.

Ectomycorrhizal and Saprotrophic Fungal Communities Vary Across mm-Scale Soil Microsites Differing in Phosphatase Activity

To understand nutrient cycling in soils, soil processes and microorganisms need be better characterized. To determine whether specific trophic groups of fungi are associated with soil enzyme activity, we used soil imprinting to guide mm-scale sampling from microsites with high and low phosphatase activities in birch/Douglas-fir stands. Study 1 involved sampling one root window per site at 12 sites of different ages(stands);study 2 was conducted at one of the stem-exclusion stands, at which 5 root windows had been installed. Total fungal and ectomycorrhizal(EM) fungal terminal-restriction fragment length polymorphism(TRFLP)fingerprints differed between high-and low-phosphatase activity microsites at 8 of 12 root windows across 12 sites. Where differences were detected, fewer EM fungi were detected in high-than low-phosphatase activity microsites. Using 5 root windows at one site,next-generation sequencing detected similar fungal communities across microsites, but the ratio of saprotrophic to EM fungal reads was higher in high-phosphatase activity microsites in the two windows that had low EM fungal richness. In windows with differences in fungal communities, both studies indicated that EM fungi were less successful than saprotrophic fungi in colonizing fine-scale,organic matter-rich microsites. Fine-scale sampling linked with in situ detection of enzyme activity revealed relationships between soil fungal communities and phosphatase activity that could not be observed at the scales employed by conventional approaches, thereby contributing to the understanding of fine-scale phosphorus cycling in forest soils.

Plant-associated fungal communities in the light of meta’omics

Approaches for the cultivation-independent analysis of microbial communities are summarized as meta’omics,which predominantly includes metagenomic,-transcriptomic,-proteomic and-metabolomic studies.These have shown that endophytic,root-associated and soil fungal communities are strongly shaped by associated plant species.The impact of plant identity on the composition of its litterssociated fungal community remains to be disentangled from the impact of litter chemistry.The composition of the plant community also shapes the fungal community.Most strikingly,adjacent plant species may share mycorrhizal symbionts even if the plants usually have different types of mycorrhizal fungi associated with them(ectomycorrhizal,ericoid and arbuscular mycorrhizal fungi).Environmental parameters weakly explain fungal community composition globally,and their effect is inconsistent at local and regional scales.Decrease in similarity among communities with increasing distance(i.e.distance decay)has been reported from local to global scales.This pattern is only exceptionally caused by spatial dispersal limitation of fungal propagules,but mostly due to the inability of the fungi to establish at the particular locality(i.e.environmental filtering or competitive exclusion).Fungal communities usually undergo pronounced seasonal changes and also differ between consecutive years.This indicates that development of the communities is usually not solely cyclic.Meta’omic studies challenge the classical view of plant litter decomposition.They show that mycorrhizal and(previously)endophytic fungi may be involved in plant litter decomposition and only partly support the idea of a succession from an Ascomycota to a Basidiomycota-dominated community.Furthermore,vertical separation of saprotrophic and mycorrhizal species in soil and sequential degradation from easily accessible to‘recalcitrant’plant compounds,such as lignin,can probably not be generalized.The current models of litter decomposition may therefore have to be eventually refined for certain ecosystems and environmental conditions.To gain deeper insights into fungal ecology,a meta’omic study design is outlined which focuses on environmental processes,because fungal communities are usually taxonomically diverse,but functionally redundant.This approach would initially identify dynamics of chemical shifts in the host and/or substrate by metametabolomics.Detected shifts would be subsequently linked to microbial activity by correlation with metatranscriptomic and/or metaproteomic data.A holistic trait-based approach might finally identify factors shaping taxonomic composition in communities against the dynamics of the environmental process(es)they are involved in.

A multilocus phylogeny for worldwide Cantharellus (Cantharellales, Agaricomycetidae)

After a short historical overview of past systematic studies on Cantharellus,discussing delimitation and species diversity of the genus as well as previous,morphology-based,infrageneric classifications,this paper presents the first molecularly-based infrageneric classification of this genus using a multigene phylogenetic approach(nucLSU,mitSSU,RPB2 and tef-1)on a dataset that covers approximately halve of the described chanterelles worldwide,including many type specimens.Six subgenera are recognized and the recognition of subgenus Afrocantharellus as a separate genus is not accepted.The taxonomic value of individual morphological features is discussed as challenged by this new multigene phylogeny which comprises five new sections,one new subgenus and many emendations for previously recognized infrageneric groups.The paper discusses the observed discrepancy in biodiversity of Cantharellus when comparing between studies that focus either on below-or above-ground presence.A preliminary biogeographic hypothesis suggests an‘out of Africa’Gondwanan origin as a result of vicariance and subsequent migrations.