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Three new species of arbuscular mycorrhizal fungi of the genus Diversispora (phylum Glomeromycota) were described based on their morphology and molecular phylogeny. The phylogeny was inferred from the analyses of the partial 45S rDNA sequences (18S-ITS-28S) and the largest subunit of RNA polymerase II ( rpb1 ) gene. These species were associated in the field with plants colonizing maritime sand dunes of the Baltic Sea in Poland and formed mycorrhiza in single-species cultures.

We examined three arbuscular mycorrhizal fungi (AMF; phylum Glomeromycota) producing glomoid spores. The mode of formation and morphology of these spores suggested that they represent undescribed species in the genus Rhizoglomus of the family Glomeraceae. Subsequent morphological studies of the spores and molecular phylogenetic analyses of sequences of the nuc rDNA small subunit (18S), internal transcribed spacer (ITS1-5.8S-ITS2 = ITS), and large subunit (28S) region (= 18S-ITS-28S) confirmed the suggestion and indicated that the fungi strongly differ from all previously described Rhizoglomus species with known DNA barcodes. Consequently, the fungi were described here as new species: R. dalpeae, R. maiae , and R. silesianum . Two of these species lived hypogeously in the field in habitats subjected to strong environmental stresses. Rhizoglomus dalpeae originated from an inselberg located within Guineo-Sudanian transition savanna zone in Benin, West Africa, where the temperature of the inselberg rock during a 5-mo drought ranges from 40 to 60 C. Rhizoglomus silesianum originated from a coal mine spoil heap in Poland, whose substrate is extremely poor in nutrients, has unfavorable texture, and may heat up to 50 C. By contrast, R. maiae was found in more favorable habitat conditions. It produced an epigeous cluster of spores among shrubs growing in a tropical humid reserve in Brazil. Moreover, the compatibility of phylogenies of species of the family Glomeraceae reconstructed from analyses of sequences of 18S-ITS-28S and the largest subunit of RNA polymerase II ( RPB1 ) gene was discussed.

The group of river corridor plants (RCP) includes vascular plant species which grow mainly or exclusively in the valleys of large rivers. Despite the long recognized fact that some plant species display a corridor-like distribution pattern in Central Europe, there is still no exhaustive explanation of the mechanisms generating this peculiar distribution. The main goal of this study was therefore to investigate whether arbuscular mycorrhizal fungi (AMF) and fungal root endophytes influence the RCP distribution. Arbuscular mycorrhizae (AM) were observed in 19 out of 33 studied RCP. Dark septate endophytes (DSE) and Olpidium spp. were recorded with low abundance in 15 and 10 plant species, respectively. The spores of AMF were found only in 32% of trap cultures established from the soils collected in the river corridor habitats. In total, six widespread AMF species were identified. Because the percentage of non-mycorrhizal species in the group of RCP is significant and the sites in river corridors are characterized by low AMF species diversity, RCP can be outcompeted outside river valleys by the widespread species that are able to benefit from AM associations in more stable plant-AMF communities in non-river habitats.

Three new species of arbuscular mycorrhizal (AM) fungi (Glomeromycota) were isolated from soil samples collected from a hyperarid sandy plain of South Arabia. Morphological characteristics of the spores clearly differentiated them from closely related AM species. Molecular analyses were performed on rDNA sequences obtained from single spores including a ~1700 bp region comprising partial SSU, ITS, partial LSU and the ~600 bp ITS region only. The phylogenetic trees based on these regions showed that the three species belong to well described genera but are clearly distinct from known species. Consequently, we describe them here as Diversispora omaniana, Septoglomus nakheelum and Rhizophagus arabicus spp. nov. D. omaniana and R. arabicus were isolated from the native, arid habitat, while S. nakheelum was isolated from a nearby irrigated date palm plantation. The discovery of three new species of AM fungi from this location suggests that a number of additional undescribed AM taxa may be present in such desert ecosystems. Further work to understand the diversity and functional significance of these new AM taxa may offer new opportunities for conservation, re-vegetation, and sustainable agriculture in extremely arid environments.

Two distinct populations of Arnica montana, an endangered medicinal plant, were studied under field conditions. The material was investigated using microscopic and molecular methods. The analyzed plants were always found to be mycorrhizal. Nineteen arbuscular mycorrhizal fungal DNA sequences were obtained from the roots. They were related to Glomus Group A, but most did not match any known species. Some showed a degree of similarity to fungi colonizing liverworts. Conventional analysis of spores isolated from soil samples allowed to identify different fungal taxa: Glomus macrocarpum, Glomus mosseae, Acaulospora lacunosa, and Scutellospora dipurpurescens. Their spores were also isolated from trap cultures.

Two new arbuscular mycorrhizal fungal species (Glomeromycota) of genus Glomus, G. africanum and G. iranicum, are described and illustrated. Both species formed spores in loose clusters and singly in soil and G. iranicum sometimes inside roots. G. africanum spores are pale yellow to brownish yellow, globose to subglobose, (60-)87(-125) μm diam, sometimes ovoid to irregular, 80-110 x 90-140 μm. The spore wall consists of a semipermanent, hyaline, outer layer and a laminate, smooth, pale yellow to brownish yellow, inner layer, which always is markedly thinner than the outer layer. G. iranicum spores are hyaline to pastel yellow, globose to subglobose, (13-)40(-56) μm diam, rarely egg-shaped, prolate to irregular, 39-54 x 48-65 μm. The spore wall consists of three smooth layers: one mucilaginous, short-lived, hyaline, outermost; one permanent, semirigid, hyaline, middle; and one laminate, hyaline to pastel yellow, innermost. Only the outermost spore wall layer of G. iranicum stains red in Melzer's reagent. In the field G. africanum was associated with roots of five plant species and an unrecognized shrub colonizing maritime sand dunes of two countries in Europe and two in Africa, and G. iranicum was associated with Triticum aestivum cultivated in southwestern Iran. In one-species cultures with Plantago lanceolata as the host plant G. africanum and G. iranicum formed arbuscular mycorrhizae. Phylogenetic analyses of partial SSU sequences of nrDNA placed the two new species in Glomus group A. Both species were distinctly separated from sequences of described Glomus species.

A new arbuscular mycorrhizal fungal species of genus Glomus, G. perpusillum (Glomeromycota), forming small, hyaline spores is described and illustrated. Spores of G. perpusillum were formed in hypogeous aggregates and occasionally inside roots. They are globose to subglobose, (10-)24(-30) microm diam, rarely egg-shaped, oblong to irregular, 18-25 x 25-63 microm. The single spore wall of G. perpusillum consists of two permanent layers: a finely laminate, semiflexible to rigid outer layer and a flexible to semiflexible inner layer. The inner layer becomes plastic and frequently contracts in spores crushed in PVLG-based mountants and stains reddish white to grayish red in Melzer's reagent. Glomus perpusillum was associated with roots of Ammophila arenaria colonizing sand dunes of the Mediterranean Sea adjacent to Calambrone, Italy, and this is the only site of its occurrence known to date. In single-species cultures with Plantago lanceolata as host plant, G. perpusillum formed vesicular-arbuscular mycorrhiza. Phylogenetic analyses of partial SSU sequences of nrDNA placed the species in Glomus group A with no affinity to its subgroups. The sequences of G. perpusillum unambiguously separated from the sequences of described Glomus species and formed a distinct clade together with in planta arbuscular mycorrhizal fungal sequences found in alpine plants.

Arbuscular mycorrhiza and fungal root endophytes of three weeds,Galium tricornutum,Lycopsis orientalisandScandix pecten-veneris, were studied in an altitudinal gradient of the Pamir Alai Mountains. Colonisation by arbuscular mycorrhizal fungi (AMF) was found in all species. Only in the case ofG. tricornutumwas there a rise in mycorrhizal parameters values found for the medium altitude range. Similar tendencies were observed in the case of the AMF colonisation potential assessment. This suggests that plant species' identity, dependency on symbiosis and interactions with soil properties determine root colonisation and the abundance of AMF in soils at the elevations in question. Four AMF species,Claroideoglomus claroideum,Funneliformis mosseae,Scutellospora dipurpurescensandSeptoglomus constrictum, were isolated from trap cultures established on soil taken from under the weeds. Dark septate endophytes (DSE) accompanied the AMF in the roots ofG. tricornutumandS. pecten-veneris; however, they were neither frequently occurring nor abundant. The sporangia ofOlpidiumspp. were observed with low frequency occurrence inG. tricornutumandS. pecten-venerisand more often in the roots ofL.orientalis. However, in both cases, they were low in abundance. No differences were found for the presence of DSE andOlpidiumin the altitudinal gradient. [ABSTRACT FROM AUTHOR]