Maria Rudawska

Relationship between genotype and soil environment during colonization of poplar roots by mycorrhizal and endophytic fungi

Poplars are among the few tree genera that can develop both ectomycorrhizal (ECM) and arbuscular (AM) associations; however, variable ratios of ECM/AM in dual mycorrhizal colonizations were observed in the roots of a variety of poplar species and hybrids. The objective of our study was to analyze the effect of internal and external factors on growth and dual AM and ECM colonization of poplar roots in three 12–15-year-old common gardens in Poland. We also analyzed the abundance of nonmycorrhizal fungal endophytes in the poplar roots. The Populus clones comprised black poplars (Populus deltoides and P. deltoides × Populus nigra), balsam poplars (Populus maximowiczii × Populus trichocarpa), and a hybrid of black and balsam poplars (P. deltoides × P. trichocarpa). Of the three sites that we studied, one was located in the vicinity of a copper smelter, where soil was contaminated with copper and lead. Poplar root tip abundance, mycorrhizal colonization, and soil fungi biomass were lower at this heavily polluted site. The total mycorrhizal colonization and the ratio of ECM and AM colonization differed among the study sites and according to soil depth. The influence of Populus genotype was significantly pronounced only within the individual study sites. The contribution of nonmycorrhizal fungal endophytes differed among the poplar clones and was higher at the polluted site than at the sites free of pollution. Our results indicate that poplar fine root abundance and AM and ECM symbiosis are influenced by environmental conditions. Further studies of different site conditions are required to characterize the utility of poplars for purposes such as the phytoremediation of polluted sites.

Ectomycorrhizal fungal communities of native and non-native Pinus and Quercus species in a common garden of 35-year-old trees

Non-native tree species have been widely planted or have become naturalized in most forested landscapes. It is not clear if native trees species collectively differ in ectomycorrhizal fungal (EMF) diversity and communities from that of non-native tree species. Alternatively, EMF species community similarity may be more determined by host plant phylogeny than by whether the plant is native or non-native. We examined these unknowns by comparing two genera, native and non-native Quercus robur and Quercus rubra and native and non-native Pinus sylvestris and Pinus nigra in a 35-year-old common garden in Poland. Using molecular and morphological approaches, we identified EMF species from ectomycorrhizal root tips and sporocarps collected in the monoculture tree plots. A total of 69 EMF species were found, with 38 species collected only as sporocarps, 18 only as ectomycorrhizas, and 13 both as ectomycorrhizas and sporocarps. The EMF species observed were all native and commonly associated with a Holarctic range in distribution. We found that native Q. robur had ca. 120% higher total EMF species richness than the non-native Q. rubra, while native P. sylvestris had ca. 25% lower total EMF species richness than non-native P. nigra. Thus, across genera, there was no evidence that native species have higher EMF species diversity than exotic species. In addition, we found a higher similarity in EMF communities between the two Pinus species than between the two Quercus species. These results support the naturalization of non-native trees by means of mutualistic associations with cosmopolitan and novel fungi.

Ectomycorrhizal community structure of different genotypes of Scots pine under forest nursery conditions.

In this paper, we report the effect of Scots pine genotypes on ectomycorrhizal (ECM) community and growth, survival, and foliar nutrient composition of 2-year-old seedlings grown in forest bare-root nursery conditions in Lithuania. The Scots pine seeds originated from five stands from Latvia (P1), Lithuania (P2 and P3), Belarus (P4), and Poland (P5). Based on molecular identification, seven ECM fungal taxa were identified: Suillus luteus and Suillus variegatus (within the Suilloid type), Wilcoxina mikolae, Tuber sp., Thelephora terrestris, Cenococcum geophilum, and Russuloid type. The fungal species richness varied between five and seven morphotypes, depending on seed origin. The average species richness and relative abundance of most ECM morphotypes differed significantly depending on pine origin. The most essential finding of our study is the shift in dominance from an ascomycetous fungus like W. mikolae in P2 and P4 seedlings to basidiomycetous Suilloid species like S. luteus and S. variegatus in P1 and P5 seedlings. Significant differences between Scots pine origin were also found in seedling height, root dry weight, survival, and concentration of C, K, Ca, and Mg in the needles. The Spearman rank correlation coefficient revealed that survival and nutritional status of pine seedlings were positively correlated with abundance of Suilloid mycorrhizas and negatively linked with W. mikolae abundance. However, stepwise multiple regression analysis showed that only survival and magnesium content in pine needles were significantly correlated with abundance of ECM fungi, and Suilloid mycorrhizas were a main significant predictor. Our results may have implications for understanding the physiological and genetic relationship between the host tree and fungi and should be considered in management decisions in forestry and ECM fungus inoculation programs.

Genetic Diversity of Naturally Established Ectomycorrhizal Fungi on Norway Spruce Seedlings under Nursery Conditions

We have assessed ectomycorrhizal fungi colonizing Norway spruce (Picea abies L.) seedlings in nine forest nurseries using restriction fragment length polymorphism (RFLP) and sequencing analyses of the internal transcribed spacers (ITS1-5.8S-ITS2) amplicons. Restriction analysis of the amplified DNA fragments with HinfI, MboI, and TaqI enzymes allowed the definition of 17 RFLP genotypes; five of them could be unambiguously assigned to Thelephora terrestris, Hebeloma longicaudum, H. crustuliniforme, Tricharina ochroleuca, and Cenococcum geophilum species by comparison with the sporocarp RFLP-pattern database. The remaining genotypes have been sequenced and compared with sequences deposited in the GenBank database. The phylogenetic analysis of resulting sequences and their identified matches indicated that isolated genotypes have formed seven clades. The ascomycetes were predominant: we have determined eight species—Wilcoxina mikolae, Phialophora finlandia, Tuber sp., Cenococcum geophilum, Tricharina ochroleuca, Pulvinula constellatio, and two unidentified ascomycetes—whereas the basidiomycetes were less common (four species denoted: Amphinema byssoides, Hebeloma crustuliniforme, H. longicaudum, and Thelephora terrestris). Wilcoxina mikolae and Phialophora finlandia were the most frequent fungi. Analysis of variance revealed that ascomycetes abundance was higher in nurseries that used organic fertilizer.

Ectomycorrhizal fungal communities of pedunculate and sessile oak seedlings from bare-root forest nurseries

In this study, we present the detailed molecular investigation of the ectomycorrhizal (ECM) community of Quercus petraea and Quercus robur seedlings grown in bare-root forest nurseries. In all tested oak samples, mycorrhizal colonization was nearly 100%. Morphological observation and molecular investigations (sequencing of fungal ITS rDNA) revealed a total of 23 mycorrhizal taxa. The most frequent and abundant fungal taxa were Hebeloma sacchariolens, Tuber sp., and Peziza sp.; from the detected fungal taxa, 20 were noted for Q. petraea and 23 for Q. robur. Depending on the nursery, the species richness of identified ECM fungal taxa for both oak species ranged from six to 11 taxa. The mean species richness for all nurseries was 5.36 and 5.82 taxa per Q. petraea and Q. robur sample, respectively. According to the analysis of similarity, ECM fungal communities were similar for Q. petraea and Q. robur (R = 0.019; p = 0.151). On the other hand, detected fungal communities were significantly different between nurseries (R = 0.927; p < 0.0001). Using the Spearman rank correlation, it was determined that the ectomycorrhizal diversity (in terms of richness, the Shannon diversity, evenness, and Simpson dominance indices) is significantly related to the soil parameters of each nursery. We conclude that individual nursery may be considered as separate ecological niches that strongly discriminate diversity of ECM fungi.

Ectomycorrhizal colonization of naturally regenerating Pinus sylvestris L. seedlings growing in different micro-habitats in boreal forest

We investigated the species richness and composition of ectomycorrhizal (EM) fungi colonizing Pinus sylvestris L. seedlings naturally regenerating in boreal forest, in three different microhabitats: on forest ground, on decaying stumps, and within moss layer on erratic boulders. We tested the hypothesis that habitat differences would affect the composition of the EM community of regenerating pine seedlings. In total, 16 EM species were detected, from which none occurred on seedlings growing in all three microhabitats. Piloderma croceum and Cenococcum geophilum were common for seedlings growing in forest ground and on boulders, while Tricholoma aestuans and Suillus luteus were shared between seedlings growing on forest ground and decaying stumps. EM species richness and composition were strikingly different between seedlings regenerating in different microhabitats. Results are discussed as a function of dispersal and niche differentiation of EM fungi.

Growth and Mycorrhizal Community Structure of Pinus sylvestris Seedlings following the Addition of Forest Litter

ABSTRACT We report the effects of pine and oak litter on species composition and diversity of mycorrhizal fungi colonizing 2-year-old Pinus sylvestris L. seedlings grown in a bare-root nursery in Lithuania. A layer of pine or oak litter was placed on the surface of the nursery bed soil to mimic natural litter cover. Oak litter amendment appeared to be most favorable for seedling survival, with a 73% survival rate, in contrast to the untreated mineral bed soil (44%). The concentrations of total N, P, K, Ca, and Mg were higher in oak growth medium than in pine growth medium. Relative to the control (pH 6.1), the pH was lower in pine growth medium (5.8) and higher in oak growth medium (6.3). There were also twofold and threefold increases in the C content of growth medium with the addition of pine and oak litter, respectively. Among seven mycorrhizal morphotypes, eight different mycorrhizal taxa were identified: Suillus luteus, Suillus variegatus, Wilcoxina mikolae, a Tuber sp., a Tomentella sp., Cenococcum geophilum, Amphinema byssoides, and one unidentified ectomycorrhizal symbiont. Forest litter addition affected the relative abundance of mycorrhizal symbionts more than their overall representation. This was more pronounced for pine litter than for oak litter, with 40% and 25% increases in the abundance of suilloid mycorrhizae, respectively. Our findings provide preliminary evidence that changes in the supply of organic matter through litter manipulation may have far-reaching effects on the chemistry of soil, thus influencing the growth and survival of Scots pine seedlings and their mycorrhizal communities.

Species and functional diversity of ectomycorrhizal fungal communities on Scots pine (Pinus sylvestris L.) trees on three different sites

Abstract• IntroductionIn the present study, we describe the aboveground (epigeous sporocarps) and belowground (ectomycorrhizal root tips and their exploration types) composition of ectomycorrhizal (ECM) fungal species on three 20-year-old Scots pine sites.• ObjectivesThe aim of this study was to relate the composition of ECM species to history of the site, stand density and soil chemistry (pH, toxic metal content, etc.) and to show how variable site condition contribute to above- and belowground ECM community changes.• ResultsECM fungi were identified by combination of morphotyping and direct sequencing of the PCR-amplified internal-transcribed spacer of n-rDNA. By identifying sporocarps and mycorrhizas, we detected a total of 54 taxa of ECM fungi: 28, 30, and 23 species at the Kórnik (control), Luboń (near the chemical plant) and Głogów (near the Copper Smelter, heavy metal influenced) sites, respectively. The sporocarp survey weakly reflected the analysis of ECM tips in terms of species composition, and largely supplemented the belowground view. Wilcoxina rehmii was the belowground-dominating species at all three sites and was found at the highest abundance at the site established after the clear cut of poplars and with the highest tree density (Kórnik). At the Luboń site, subdominant mycorrhizas were formed by Phialophora finlandia. On the site near the Copper Smelter in Głogów, a significant shift in species composition was observed compared with the two other sites and a very large proportion of medium-fringe exploration type belonging to Atheliaceae was found. Despite the partial overlap in the nonmetric multi-dimensional scaling ordination, analysis of similarity revealed significant differences between tested sites.• ConclusionBecause of the number of covarying site properties which may influence ECM communities, it is difficult, if not unfeasible, to separate the precise reasons of the distribution of ECM fungi. Continued research on the biodiversity of ECM fungi in field sites along an environmental gradient would greatly improve our understanding of the effects of ecological conditions on the functional diversity of mycorrhizal fungi.

Diversity of ectomycorrhizal fungus assemblages on nursery grown European beech seedlings

Abstract• ContextAn important feature of forest nursery management is the production of first-rate planting stock, which is closely connected with an adequate development of ectomycorrhizas on seedling roots.• AimsThe aim of this study was to provide a detailed assessment of the ectomycorrhizal (ECM) fungal diversity of European beech grown in bare-root forest nursery conditions.• MethodsMorphological and molecular analyzes were used to identify ECM fungi, quantify fungal richness, and record differences in the relative abundance of individual taxa.• ResultsTwenty-seven different mycorrhizal fungal taxa were found in four tested nurseries. Of these 27, only 6 were present in more than one nursery. Taxa richness in individual nurseries ranged from 6 to 13, indicating that ECM colonization potential is nursery-dependent. The most frequent taxa were: Tuber sp. 1, Cadophora sp., Cenococcum geophilum agg., Hebeloma sacchariolens, and Laccaria tortilis. According to the analysis of similarity, ECM fungal communities were significantly different between nurseries (R = 0.7741; p < 0.0001).• ConclusionBeech seedlings grown in bare-root nurseries are colonized by a highly diverse suite of ECM fungi; thus, artificial inoculation of seedlings is generally not necessary in nursery practice.

Ectomycorrhizae of Young and Mature Scots Pine Trees in Industrial Regions in Poland

Abstract Ectomycorrhizae are obligate symbiotic structures of forest tree roots and are susceptible to environmental changes. Ectomycorrhizae of Scots pine ( Pinus sylvestris L.) trees grown in forests influenced by different levels of air pollutants were investigated. Total numbers of mycorrhizal root tips in the soil horizons and the frequency of mycorrhizal morphotypes were studied as indicators of ectomycorrhizal status. The studies were conducted in two comparable young plantations in western Poland with high and low pollution exposure and in two mature forest ecosystems in southern Poland differing in pollution exposure. At the young Scots pine plantation with high pollution exposure (Lubon), numbers of mycorrhizal root tips in the soil layer 0–5 cm were lower during three growing seasons than at the cleaner site (Kornik). In the soil layer 15–30 cm the total number of mycorrhizal root tips was found slightly higher at the polluted than at the control site. There was no difference in the frequency of the seven mycorrhizal morphotypes found at the two young plantations. At the heavily polluted mature forest stand (Niepolomice Forest) the total number of mycorrhizal root tips was lower in zones of severe pollution levels than in the less polluted zones. Moreover, the average number of mycorrhizae in the Niepolomice Forest was lower than in the moderately polluted forest ecosystem (Ratanica catchment). The mycorrhizal diversity of the mature pines in the heavily polluted forest was reduced (four morphotypes) as compared to the moderately polluted forest (eight morphotypes). The relationship between industrial pollution and mycorrhizal status was more pronounced at the mature Scots pine stands than at the young plantations.