Arbuscular mycorrhizal fungi associated with common pteridophytes in Dujiangyan,southwest China

The colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with common pteridophytes were investigated in Dujiangyan, southwest China. Of the 34 species of ferns from 16 families collected, 31 were colonized by AM fungi. The mean percentage root length colonized was 15%, ranging from 0 to 47%. Nineteen species formed Paris-type and 10 intermediate-type AM. In two ferns, only rare intercellular non-septate hyphae or vesicles were observed in the roots and AM type could not be determined. Of the 40 AM fungal taxa belonging to five genera isolated from rooting-zone soils, 32 belonged to Glomus, five to Acaulospora, one to Archaeospora, one to Entrophospora, and one to Gigaspora. Acaulospora and Glomus were the dominant genera and Glomus versiforme was the most common species. The average AM spore density was 213 per 100 g air-dried soil and the average species richness was 3.7 AM species per soil sample. There was no correlation between spore density and percentage root length colonized by AM fungi.     

Arbuscular mycorrhizal status of spring ephemerals in the desert ecosystem of Junggar Basin, China

A survey was made of the arbuscular mycorrhizal (AM) status of 73 spring ephemeral plant species that grow in the desert ecosystem of Junggar Basin, northwest China. The proportion of AM colonization ranged from 7 to 73% with a mean value of 30%. A total of 65 plant species studied were AM with coils/arbuscules or vesicles and the remaining eight species were possibly AM with no coils/arbuscules or vesicles but with fungal mycelia in the root cortex. AM fungal spores were isolated from rhizosphere samples of all 73 plant species and identified. The mean spore density was 22 per 20 ml of air-dried soil, ranging from 0 to 120. Colonization and spore density of perennials were slightly higher than of annuals and varied among different plant families. A total of 603 AM fungal spore (or sporocarp) specimens were isolated belonging to six genera, Acaulospora, Archaeopora, Entrophospora, Glomus, Paraglomus, and Scutellospora; Glomus was the dominant genus. We conclude that spring ephemerals may be highly dependent on AM associations for survival in the very infertile and arid soils of this desert ecosystem.Electronic supplementary material Supplementary material is available for this article at     

Mycorrhizae in Adenostoma fasciculatum Hook. & Arn.: a combination of unusual ecto- and endo-forms

 The mycorrhizal status of Adenostoma fasciculatum, the dominant shrub in California chaparral, has been unclear. In two typical, nearly monospecificstands, A. fasciculatum was found to have arbuscules and intercellular hyphae. Antisera detected hyphae of the arbuscular mycorrhizal (AM) fungal genera Acaulospora, Glomus, and Scutellospora, although we found only spores of Glomus. Some roots had partial sheaths and inter- and intracellular septate fungi without indications of root necrosis. Ectomycorrhizal root tips were also found, including Cenococcum and other unknown taxa. Sporocarps of EM fungi including species of Rhizopogon, Pisolithus, Balsamia, Laccaria, Hygrophorus, and Cortinarius were found in the stand, with no other EM or arbutoid mycorrhizal plants nearby. These observations indicate that A. fasciculatum forms mycorrhizae with AM, septate, and EM fungi, but often fails to form easily recognizable mycorrhizal structures. Accepted: 5 September 1998     

Arbuscular mycorrhizal fungi associated with sedges on the Tibetan plateau

The arbuscular mycorrhizal (AM) status of nine dominant sedge species and the diversity of AM fungi in Tibetan grassland were surveyed in the autumn of 2003 and 2004. Most of the sedge species and ecotypes examined were mycorrhizal, but Carex moorcroftii and Kobresia pusilla were of doubtful AM status, and Kobresia humilis was facultatively mycorrhizal. This is the first report of the mycorrhizal status of eight of the nine sedge species examined. Intraradical vesicles and aseptate hyphae were the structures most frequently observed. Appressoria, coils, and arbuscules were found in the roots of a few sedge species. A strong negative correlation was found between soil organic matter content and the extent of mycorrhizal colonization. Using trap cultures, 26 species of AM fungi belonging to six genera, Glomus, Acaulospora, Paraglomus, Archaeospora, Pacispora, and Scutellospora, were isolated from the soil samples collected. The frequency of occurrence of different taxa of AM fungi varied greatly. Glomus and Acaulospora were the dominant genera, and Acaulospora scrobiculata was the most frequent and abundant species. The species richness of AM fungi was 2.73 in the study area. Species richness and diversity index differed among the sedge species but were not correlated with soil factors such as pH, available P, or organic matter content.     

Interactions between Lotus japonicus genotypes and arbuscular mycorrhizal fungi

Abstract

Interactions between three genotypes (Ljsym 71-1, Ljsym 71-2 and Ljsym 72) of Lotus japoicus and one isolate from each of four species of arbuscular mycorrhizal fungi (Glomus sp. R-10, Glomus intraradices, Glomus etunicatum, and Gigaspora margarita) were investigated and compared with the wild-type ‘Gifu’ B-129. All the three genotypes showed no or defective internal colonization after inoculation with these AM fungi. In Ljsym72 mutant, the AM fungi produced deformed appressoria on the root surface, but failed to form any internal structures (internal hyphae, arbuscules and vesicles) except only in Glomus intraradices. The Ljsym71-1 and Ljsym71-2 mutants had more deformed appressoria and occasionally formed internal hyphae, arbuscules and vesicles, depending on AM fungi used. Wild-type ‘Gifu’ (nod⁺myc⁺) plants had typical colonization. The colonization of mutants by several fungi varied and provides a basis for studying recognition and compatibility between plants and mycorrhizal fungal species. These mutants also will be useful in studies of the genetics of the symbiosis between plant species and AM fungi.     

Arbuscular mycorrhizal fungi associated with the Meliaceae on Hainan island, China

Species richness, spore density, frequency of occurrence, and relative abundance of AM fungi were determined in rhizosphere soil samples from nine tropical rainforest sites on Hainan island, south China, and the arbuscular mycorrhizal (AM) status of members of the Meliaceae was examined. All 28 plant taxa investigated (25 species including two varieties of 1 species and three varieties of another) were colonized by AM fungi. The mean proportion of root length colonized was 56% (range 10–95%). Vesicles were observed in 27 and hyphal coils in 26 of the 28 plant taxa. Mycorrhizas were of the Paris-type or intermediate-type, with no Arum-type mycorrhizas observed. Species richness of AM fungi varied from 3 to 15 and spore density from 46 to 1,499 per 100 g rhizosphere soil. Of 33 AM fungal taxa in five genera isolated and identified, 18 belonged to Glomus, 9 to Acaulospora, 1 to Entrophospora, 2 to Gigaspora, and 3 to Scutellospora. Acaulospora and Glomus were the dominant genera identified. Glomus claroideum was the taxon most commonly isolated, with a frequency of occurrence of 56.5% and relative abundance of 10.4%. A positive correlation was found between percentage of root length colonization and species richness. However, there was no correlation between spore density and percentage of root length colonized by AM fungi.     

Enkianthus campanulatus (Ericaceae) is commonly associated with arbuscular mycorrhizal fungi

Enkianthus is the most basal extant genus in the phylogeny of ericaceous plants. Its members harbor arbuscular mycorrhiza (AM)-like hyphal structures in their roots but, as yet, no study has surveyed the AM fungal species component. Roots from six species of Enkianthus were collected from five distantly located sites in Japan. Intracellular hyphal coils were observed in the root cortical cells of all species. Fungal DNA sequences of the small subunit ribosomal RNA gene were obtained from 73 of 75 segments of Enkianthus campanulatus roots by PCR using either AML2 or NS31/AM1primer pairs. Results indicated that all E. campanulatus trees were extensively associated with Glomus spp. A phylogenetic analysis showed that 71 root segments harbored fungi belonging to Glomus group A. Among eight delineated clades, seven did not nest with any known AM fungal species. One clade was detected in all roots at all sites at relatively high frequencies, but the rest were detected sporadically at each site. The placement of sequences from distantly located sites into a single clade without known AM fungal species suggests the common association of E. campanulatus with particular AM fungal taxa.     

Specific arbuscular mycorrhizal fungi associated with non-photosynthetic Petrosavia sakuraii (Petrosaviaceae)

Mycorrhizal fungi in roots of the achlorophyllous Petrosavia sakuraii (Petrosaviaceae) were identified by molecular methods. Habitats examined were plantations of the Japanese cypress Chamaecyparis obtusa in Honshu, an evergreen broad-leaved forest in Amami Island in Japan and a mixed deciduous and evergreen forest in China. Aseptate hyphal coils were observed in root cortical cells of P. sakuraii, suggesting Paris-type arbuscular mycorrhiza (AM). Furthermore, hyphal coils that had degenerated to amorphous clumps were found in various layers of the root cortex. Despite extensive sampling of P. sakuraii from various sites in Japan and China, most of the obtained AM fungal sequences of the nuclear small subunit ribosomal RNA gene were nearly identical and phylogenetic analysis revealed that they formed a single clade in the Glomus group A lineage. This suggests that the symbiotic relationship is highly specific. AM fungi of P. sakuraii were phylogenetically different from those previously detected in the roots of some mycoheterotrophic plants. In a habitat in C. obtusa plantation, approximately half of the AM fungi detected in roots of C. obtusa surrounding P. sakuraii belonged to the same clade as that of P. sakuraii. This indicates that particular AM fungi are selected by P. sakuraii from diverse indigenous AM fungi. The same AM fungi can colonize both plant species, and photosynthates of C. obtusa may be supplied to P. sakuraii through a shared AM fungal mycelial network. Although C. obtusa plantations are widely distributed throughout Japan, P. petrosavia is a rare plant species, probably because of its high specificity towards particular AM fungi.     

The diversity of arbuscular mycorrhizas of selected Australian Fabaceae

Abstract

Members of the Australian native perennial Fabaceae have been little explored with regard to their root biology and the role played by arbuscular mycorrhizal (AM) fungi in their establishment, nutrition and long-term health. The ultimate goal of our research is to determine the dependency of native perennial legumes on their co-evolved AM fungi and conversely, the impact of AM fungal species in agricultural fields on the productivity of sown native perennial legume pastures. In this paper we investigate the colonisation morphology in roots and the AMF, identified by spores extracted from rhizosphere soil, from three replicate plots of each of the native legumes, Cullen australasicum, C. tenax and Lotus australis and the exotic legumes L. pedunculatus and Medicago sativa. The plants were grown in an agricultural field. The level and density of colonisation by AM fungi, and the frequency of intraradical and extraradical hyphae, arbuscules, intraradical spores and hyphal coils all differed between host plants and did not consistently differ between native and exotic species. However, there were strong similarities between species in the same genus. The three dominant species of AM fungi in rhizosphere soil also differed with host plant, but one fungus (Glomus mosseae) was always the most dominant. Sub-dominant AM species were the same between species in the same genus. No consistent differences in dominant spores were observed between the exotic and native Fabaceae species. Our results suggest that plant host influences the mycorrhizal community in the rhizosphere soil and that structural and functional differences in the symbiosis may occur at the plant genus level, not the species level or due to provenance.     

Detection of arbuscular mycorrhizal fungal spores in the air across different biomes and ecoregions

Aerial dispersal of fungal spores is common, but the role of wind and air movement in dispersal of spores of arbuscular mycorrhizal (AM) fungi is largely unknown. Several studies have examined the possibility of AM fungal spores being moved by wind vectors without observing spores taken from the air environment. For the first time this study observed the presence of AM fungal spores in the air. The frequency of AM fungal spores in the air was determined in six North American biomes composed of 18 ecoregions. Multiple samples were taken from both the air and the soil at each location. AM fungal spores were found in high abundance in the soil (hundreds of spores per gram of soil), however, they were rarely found in the air (most samples contained no AM fungal spores). Furthermore, only the Glomus morphotype was found in the air, whereas spores in the soil were taxomomically more diverse (Glomus, Acaulospora, Gigaspora, Scutellospora morphotypes were observed). The proportion of Glomus spores in the air relative to Glomus spores in the soil was highest in more arid systems, indicating that AM fungi may be more likely to be dispersed in the air in such systems. Nonetheless, the results indicate that the air is not likely a dominant mode of dispersal for AM fungi.     

Effect of forest fire on number, viability and post-fire re-establishment of arbuscular mycorrhizae

 Forest fire can affect arbuscular mycorrhizal (AM) fungi by changing the soil conditions and by directly altering AM proliferation. We studied the effects of a severe forest fire at Margalla Hills near Islamabad on the number and viability of AM fungal propagules in the burnt soil and their role in the re-establishment of post-fire infection in colonized plants. Compared with a nearby control area, the burnt site had a similar number of total spores but a lower number of viable AM fungal propagules. The roots of the two most frequent species at the burnt site, Dodonaea viscosa and Aristida adscensionis, showed a gradual increase in percentage root length colonized by AM fungi in general and hyphal infection in particular. Our results indicate resumption of mycorrhizal activity following the fire, probably from AM hyphae in the roots of these dominant shrubs. Accepted: 18 July 1997     

Arbuscular mycorrhizal fungi in roots of non-photosynthetic plants, <Emphasis Type="Italic">Sciaphila japonica</Emphasis> and <Emphasis Type="Italic">Sciaphila tosaensis</Emphasis> (Triuridaceae)

The mycorrhizal fungi in the roots of achlorophyllous Sciaphila japonica and S. tosaensis (Triuridaceae) were identified by molecular methods. The habitats of S. japonica were in a tree plantation of Japanese cypress, Chamaecyparis obtusa, and bamboo forests, and those of S. tosaensis were in a camellia forest and a bamboo forest. In the root cortical cells of both plants, aseptate hyphal coils were observed, which suggested the Paris-type arbuscular mycorrhiza (AM). A phylogenetic analysis based on a partial sequence of an AM fungal nuclear small subunit ribosomal RNA gene showed that the fungal DNA sequences of S. japonica were separated into three closely related clades. Those of S. tosaensis were separated into two clades, which were also closely related to each other. The AM fungi of S. japonica and S. tosaensis were completely separated in the phylogenetic tree even among those found in the same habitat, which suggests the high specificities in the plant-fungal partnerships. All the detected AM fungi in these plants belonged to Glomus-group A. Even though the habitats are in quite common environments, both plant species are known as endangered species in Japan. Such a definite specificity in AM symbioses seems to restrict the distribution of the myco-heterotrophic plants.     

Positive association between mycorrhiza and foliar endophytes in Poa bonariensis, a native grass

The interaction between mycorrhiza and leaf endophytes (Neotyphodium sp.) was studied in three Poa bonariensis populations, a native grass, differing significantly in endophyte infection. The association between endophytes and mycorrhizal fungi colonisation was assessed by analysing plant roots collected from the field. We found that roots from endophyte-infected populations showed a significantly higher frequency of colonisation by mycorrhizal fungi and that soil parameters were not related to endophyte infection or mycorrhiza colonization. In addition, we did not observe significant differences in the number of AM propagules in soils of the three populations sites. We also report the simultaneous development of Paris-type and Arum-type mycorrhiza morphology within the same root systems of P. bonariensis. The co-occurrence of both colonisation types in one and the same root system found in the three populations, which differed in Neotyphodium infection, suggests that foliar endophytes do not determine AM morphology. The percentage of root length colonised by different types of fungal structures (coils, arbuscules, longitudinal hyphae and vesicles) showed significant and positive differences in arbuscular frequency associated with endophyte infection, whereas the much smaller amounts of vesicles and hyphal coils did not differ significantly.     

Arbuscular mycorrhizal fungi in non-grazed,restored and over-grazed grassland in the Inner Mongolia steppe

Arbuscular mycorrhizal (AM) fungal diversity was investigated in non-grazed, restored and over-grazed (fenced) plots of a grassland in the Inner Mongolia steppe. Plant cover and variety differ between the plots, being highest in the non-grazed to lowest in the over-grazed plots. A total of 19 AM fungal taxa belonging to six genera were found based on spores isolated from field samples and trap cultures. One belonged to Acaulospora, one to Archaeospora, one to Entrophospora, one to Gigaspora, 12 to Glomus and three to Scutellospora. Glomus was the dominant genus in all plots, and Glomus geosporum was the dominant species, whilst G. albidum and G. etunicatum were dominant in the restored plot. Scutellospora was the second dominant genus in the non-grazed plot with Scutellospora calospora being the dominant species. The mean spore density and mean species richness of AM fungi were significantly decreased by long-term over-grazing. The Sorenson’s similarity coefficients of AM fungal community composition ranged from 0.5 to 0.64 among the three types of plot management. The results suggest that the AM fungal diversity is greatly affected by long-term over-grazing and that fencing of degraded areas partly restores plant cover and AM fungal diversity in grassland ecosystems.     

Diversity of arbuscular mycorrhizal fungi colonising roots of the grass species<Emphasis Type="Italic"> Agrostis capillaris</Emphasis> and<Emphasis Type="Italic"> Lolium perenne</Emphasis> in a field experiment

Analysis of arbuscular mycorrhizal (AM) fungal diversity through morphological characters of spores and intraradicular hyphae has suggested previously that preferential associations occur between plants and AM fungi. A field experiment was established to investigate whether AM fungal diversity is affected by different host plants in upland grasslands. Indigenous vegetation from plots in an unimproved pasture was replaced with monocultures of either Agrostis capillaris or Lolium perenne. Modification of the diversity of AM fungi in these plots was evaluated by analysis of partial sequences in the large subunit (LSU) ribosomal RNA (rDNA) genes. General primers for AM fungi were designed for the PCR amplification of partial sequences using DNA extracted from root tissues of A. capillaris and L. perenne. PCR products were used to construct LSU rDNA libraries. Sequencing of randomly selected clones indicated that plant roots were colonised by AM fungi belonging to the genera Glomus, Acaulospora and Scutellospora. There was a difference in the diversity of AM fungi colonising roots of A. capillaris and L. perenne that was confirmed by PCR using primers specific for each sequence group. These molecular data suggest the existence of a selection pressure of plants on AM fungal communities.     

不同生境下川麦冬根围土壤丛枝菌根真菌多样性北大核心CSCD

采用高通量(Illumina Miseq)测序技术对栽培和野生2种生境下川麦冬根围的丛枝菌根(AM)真菌多样性和群落结构进行测定,并结合土壤理化因子进行相关性分析,以明确两种生境下川麦冬根围土壤AM真菌多样性和优势群落的分布特点,探讨AM真菌群落分布差异的驱动因子,为AM真菌应用于麦冬生产提供理论依据和技术支持。结果表明:(1)不同生境下川麦冬根围土壤中共鉴定出AM真菌3属10种,其中野生川麦冬根围土壤鉴定出的AM真菌3属7种,分别隶属于无梗囊霉属(Acaulospora)、多孢囊霉属(Diversispora)和球囊霉属(Glomus),而栽培环境下鉴定出AM真菌1属6种,隶属于球囊霉属。2个生境优势属均为球囊霉属。(2)不同生境下川麦冬根围AM真菌之间存在显著差异,野生生境下川麦冬根围土壤AM真菌多样性指数ACE和Shannon均显著高于人工栽培生境,而Simpson指数则相反。(3)相关性分析表明,AM真菌多样性指数及群落组成结构均与土壤理化因子存在相关性,其中全钾(TK)、全磷(TP)、全氮(TN)对AM真菌多样性指数和群落结构组成均存在显著影响。研究认为,不同生境下川麦冬根围AM真菌群落存在显著差异,球囊霉属为川麦冬互利共生的关键属,TK、TP、TN是不同生境川麦冬根围AM真菌群落差异的主要驱动因子。     

A preliminary survey of the arbuscular mycorrhizal status of grassland plants in southern Tibet

We report for the first time the arbuscular mycorrhizal (AM) status of native plant species and AM fungal diversity in the grasslands of southern Tibet. A total of 51 soil samples were collected from the rhizospheres of the dominant plant species, and AM fungal structures were observed in 18 (82%) of 22 plant species examined. Vesicles and aseptate hyphae were the structures most frequently observed in the plant roots. After trap culture for 5 months, 25 AM fungal taxa were identified in the soil samples collected, of which nine belonged to Glomus, ten to Acaulospora, one to Entrophospora and five to Scutellospora. The frequency of occurrence of different genera and species varied greatly. Glomus was the dominant genus, and the most frequent and abundant species was Glomus mosseae. Over the whole sampling area, spore density in the rhizosphere soil of different host plant species ranged from 2 to 66 per 20 g air-dried soil. Overall AM fungal species richness was 2.10 and species diversity was 2.35. AM fungal diversity was also compared among the four different land use types (farmland and normal, disturbed and highly disturbed montane scrub grassland). Spore densities in the farmland and normal grassland were much higher than in the grasslands that had been degraded to varying degrees. The species richness in normal grassland was the highest of the four land use types examined. Species diversity varied from 1.99 to 0.94 and was highest in normal grassland, intermediate in degraded grassland and farmland, and lowest in the highly disturbed grassland.     

Production of Polyclonal and Monoclonal Antibodies Against Hyphae from Arbuscular Mycorrhizal Fungi

Abstract

Polyclonal and monoclonal antibodies were produced against hyphae of the arbuscular mycorrhizal fungus Glomus monosporum. The polyclonal antibodies (pAbs) were raised in a rabbit by immunizing with hyphae. They were tested for their specificity by a dot-immunoblot assay (DIBA). After the third immunization, a distinct difference in the signal strength was observed between the antisera and the preimmune serum. The pAbs showed cross-reactions to a number of fungal species, both mycorrhizal and other. For the production of monoclonal antibodies (mAbs), mice were immunized intraperitoneally with hyphae. The resulting hybridoma cell culture supernatants were tested by an indirect immunolabeling procedure. For this purpose the hyphae were immobilized on silane-coated microscopic slides. The mAb 8A7 reacted with hyphae from all Glomus isolates tested so far. Cross-reactivities were not observed with hyphae from fungi of the family Acaulosporaceae, phytopathogenic fungi tested so far, or from spores from Glomus species.     

General microflora,arbuscular mycorrhizal colonization and occurrence of endophytes in the rhizosphere of two age groups of <Emphasis Type="Italic">Ginkgo biloba</Emphasis> L.of Indian Central Himalaya

The populations of the general microflora (bacteria, actinomycetes and fungi) in the rhizosphere and their corresponding non-rhizosphere soil samples of Ginkgo biloba L. of two age groups (Group A, <25 years-young trees; Group B, >60 years-old trees) growing under a temperate location of Indian Himalayan Region (IHR) have been determined. Observations were also made for the diversity, distribution and colonization of arbuscular mycorrhizal (AM) fungi and occurrence of endophytes in roots of G. biloba. The population of general microflora was found to be higher in the rhizosphere of Group B trees, more clearly reflected in terms of rhizosphere: soil (R:S) ratios. Contrary to this, per cent colonization and spore densities of AM fungi were higher in the rhizosphere of Group A trees as compared to the rhizosphere of Group B. AM fungal colonization was observed mostly in form of loose coils. All the spores detected, belonged to the genus Glomus with five different types. Presence of endophytes (both bacteria and fungi) was observed in the cortical cells of G. biloba roots, more profound in case of Group B trees. Data suggest that, while the species of Glomus dominated the rhizosphere of G. biloba, an inverse correlation exist between the colonization of general microflora and the colonization of AM fungi including endophytes.     

Defoliation effects on the community structure of arbuscular mycorrhizal fungi based on 18S rDNA sequences

The effects of defoliation on arbuscular mycorrhizal (AM) associations in the field were investigated in terms of the community structure of AM fungi colonizing roots of grassland plants; the carbohydrate balance of the host plants was also determined. We focused on two plant species dominating Japanese native grasslands: the grazing-intolerant species Miscanthus sinensis and the grazing-tolerant species Zoysia japonica. Community structures of AM fungi were determined from 18S rRNA gene sequences. The dominant fungal group in both plant species was the Glomus clade, which was classified into several phylogenetic groups based on genetic distances and topology. In Miscanthus roots, the Glomus-Ab, Glomus-Ac, and Glomus-Ad groups were detected almost equally. In Zoysia roots, the Glomus-Ab group was dominant. Defoliation effects on the community structure of AM fungi differed between the plant species. In Miscanthus roots, the percentage of root length colonized (%RLC) by the Glomus-Ac and Glomus-Ad groups was significantly reduced by defoliation treatment. On the other hand, AM fungal group composition in Zoysia roots was unaffected by defoliation except on the last sampling date. Decreased %RLC by Glomus-Ac and Glomus-Ad coincided with decreased non-structural carbohydrate (NSC) levels in host plants; also, significant positive correlations were found between the %RLC and some NSC levels. On the other hand, the %RLC by Glomus-Ab in both plant species was unaffected by the NSC level. These results suggest that AM fungal groups have different carbohydrate requirements from host plants.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00572-003-0286-x