In vitro evaluation of the tolerance of arbuscular mycorrhizal fungi (AMF) isolated from alkaline-saline soils at different pH and salinity ranges in their pre-symbiotic states

SILVANI, VANESA ANALÍA; GODEAS, ALICIA MARGARITA; STATELLO, MARINA; FRACCHIA, SEBASTIÁN; SCORZA, MARÍA VICTORIA; COLOMBO, ROXANA

San Carlos de Bariloche

Simposio; II International Symposium Mycorrhizal Symbiosis in South America; 2019

Universidad Nacional del comahue

The Laguna Brava Provincial Reserve is located northwest of the province of La Rioja and is formed by a series of high Andean lakes exposed to extreme environmental factors: high incidence of UV radiation, low rainfall, low oxygen pressure, high salinity and concentration of heavy metals, alkaline pHs, and oligotrophy. These types of extreme ecosystems are fundamental for the conservation of microorganisms with phenotypes and genotypes with particular adaptations, which would not be found in others environments. The soils of the margins of the lagoons are naturally enriched with salts and heavy metals, and have AMF associated with the scarce vegetation. The aims of this work was to select three species of AMF isolated from high-Andean lagoons of the "Laguna Brava" and to evaluate the effect and tolerance on spore germination and hyphal development of these species according to different ranges of pH and salinity. For that, spores or sporocarps of Funneliformis mosseae, Entrophospora infrequens and Funneliformis sp. were incubated in gellified medium with different salt concentrations (NaCl) or different pH ranges. Percentage of germination, viability of ungerminated spores, hyphal length and number of hyphal tips of germinated spores were registered. The germination of the spores and their hyphal development in the three species varied according to the pH values. At acidic pH, none AMF germinated despite the high percentage of viable spores. At alkaline pH, there was a high percentage of germination and pre-symbiotic development in spores of E. infrequens and Funneliformis sp., observing an increase in length and hyphal branching at pH 8 and pH 10, respectively. Salinity negatively affected the germination and pre-symbiotic development of spores of E. infrequens and Funneliformis sp., but not their viability. As the salinity increased, the length and the hyphal branches of the germinated spores decreased in both species. The strain of F. mosseae showed almost no germination under the different conditions of pH and salinity despite its high viability, indicating a probable dormancy in its spores. Salinity tolerant strains with optimal growth characteristics under alkaline conditions could be selected for the formulation of a bio-inoculant based on AMF applicable to alkaline-saline soils.