Three new arbuscular mycorrhizal Diversispora species in Glomeromycota

Bioprospecting for plant resilience to climate change: mycorrhizal symbionts of European and American beachgrass (Ammophila arenaria and Ammophila breviligulata) from maritime sand dunes

Climate change and global warming have contributed to increase terrestrial drought, causing negative impacts on agricultural production. Drought stress may be addressed using novel agronomic practices and beneficial soil microorganisms, such as arbuscular mycorrhizal fungi (AMF), able to enhance plant use efficiency of soil resources and water and increase plant antioxidant defence systems. Specific traits functional to plant resilience improvement in dry conditions could have developed in AMF growing in association with xerophytic plants in maritime sand dunes, a drought-stressed and low-fertility environment. The most studied of such plants are European beachgrass (Ammophila arenaria Link), native to Europe and the Mediterranean basin, and American beachgrass (Ammophila breviligulata Fern.), found in North America. Given the critical role of AMF for the survival of these beachgrasses, knowledge of the composition of AMF communities colonizing their roots and rhizospheres and their distribution worldwide is fundamental for the location and isolation of native AMF as potential candidates to be tested for promoting crop growth and resilience under climate change. This review provides quantitative and qualitative data on the occurrence of AMF communities of A. arenaria and A. breviligulata growing in European, Mediterranean basin and North American maritime sand dunes, as detected by morphological studies, trap culture isolation and molecular methods, and reports on their symbiotic performance. Moreover, the review indicates the dominant AMF species associated with the two Ammophila species and the common species to be further studied to assess possible specific traits increasing their host plants resilience toward drought stress under climate change.

Three new species of arbuscular mycorrhizal fungi (Glomeromycota) and Acaulospora gedanensis revised

Studies of the morphology and the 45S nuc rDNA phylogeny of three potentially undescribed arbuscular mycorrhizal fungi (phylum Glomeromycota) grown in cultures showed that one of these fungi is a new species of the genus Diversispora in the family Diversisporaceae; the other two fungi are new Scutellospora species in Scutellosporaceae. Diversispora vistulana sp. nov. came from maritime sand dunes of the Vistula Spit in northern Poland, and S. graeca sp. nov. and S. intraundulata sp. nov. originally inhabited the Mediterranean dunes of the Peloponnese Peninsula, Greece. In addition, the morphological description of spores of Acaulospora gedanensis, originally described in 1988, was emended based on newly found specimens, and the so far unknown phylogeny of this species was determined. The phylogenetic analyses of 45S sequences placed this species among Acaulospora species with atypical phenotypic and histochemical features of components of the two inner germinal walls.

Three new species of arbuscular mycorrhizal fungi of the genus Diversispora from maritime dunes of Poland

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.

Celebrating INVAM: 35 years of the largest living culture collection of arbuscular mycorrhizal fungi

The International Culture Collection of (Vesicular-) Arbuscular Mycorrhizal Fungi-INVAM-the largest living culture collection of arbuscular mycorrhizal fungi (AMF) celebrated its 35th year in 2020. The authors record here the mission and goals of INVAM, its contribution as a living culture collection, some historical aspects of INVAM, and describe the advances in mycorrhizology and AMF systematics after INVAM moved to West Virginia University. This commentary emphasizes the importance of a living culture collection to preserve germplasm and to educate and assist researchers in mycorrhizal science.

Sieverdingia gen. nov., S. tortuosa comb. nov., and Diversispora peloponnesiaca sp. nov. in the Diversisporaceae (Glomeromycota)

Phylogenetic analyses of 18S–ITS–28S nuc rDNA sequences indicated that the arbuscular mycorrhizal fungus originally described asGlomus tortuosumand later transferred to the genusCorymbiglomusrepresents a separate, previously unrecognized clade at the rank of genus in the family Diversisporaceae (order Diversisporales, phylum Glomeromycota). The analyses located the clade between clades representing the generaDesertisporaandRedeckera. Consequently, a new genus,Sieverdingia, was erected, withS. tortuosacomb. nov. The unique morphological feature ofS. tortuosais the formation of glomoid-like spores with a single-layered spore wall covered with a hyphal mantle. Importantly, the erection ofSieverdingiaclarified the definition ofCorymbiglomus, which currently consists of three species producing glomoid-like spores with one, three- to four-layered spore wall. The features of the innermost layer, which is hyaline, laminate, flexible to semi-flexible, indicate that it is a synapomorphy ofCorymbiglomus. The definitions ofCorymbiglomusand its species were emended. Moreover, the distribution ofS. tortuosaand the three species ofCorymbiglomuswas discussed based on own studies, literature data, and molecular sequences deposited in public databases. We concluded that the distribution ofS. tortuosaandC. globiferumknown in environmental studies based on their partial 28S nuc rDNA sequences only may be understated because the main molecular characteristics distinguishing these species reside outside the 28S region. Finally, we described a new species in the genusDiversisporaoriginating from Mediterranean dunes of the Peloponnese peninsula, Greece. The same phylogenetic analyses mentioned above indicated that the closest relative of the new species, producing dark-coloured spores, isD. clara, whose spores are creamy white at most.

Sanger and next generation sequencing in the characterisation of arbuscular mycorrhizal fungi (AMF) in Pancratium maritimum L. (Amaryllidaceae), a representative plant species of Mediterranean sand dunes

An interesting AMF colonization microcosm has been detected in the roots of Pancratium maritimum (sea daffodil). Both sequencing techniques (Sanger and NGS) have been used for AMF characterisation, showing a balanced trade-off between pros and cons. By Sanger and next generation sequencing of rRNA nuclear molecular markers (SSU-ITS-LSU and ITS2, respectively), the presence of AMF communities in the roots of P. maritimum was evaluated. Our results shed light on the presence of AMF in sea daffodil and the diversity of assemblages of AMF detected after Sanger sequencing of the SSU-ITS-LSU marker is much higher than that determined following NGS sequencing of ITS2 alone.