THE SEARCH FOR EFFECTIVE SYMBIOSES BETWEEN PLANTS AND MICROORGANISMS INHABITING SOILS OF SARDINIA.

Collaboration between ARRIAM (Russian Federation) and ISPAAM-CNR (Italy) related to plant-microbe interactions was established in 2000. Up to now, two joint research projects within the Italy-Russia Commission for Science and Technology Cooperation have been performed. The first project "Isolation, characterization and utilization of root nodule bacteria specific to pasture legumes and selection of high effective strains" was developed on the National Park of Asinara island (Sardinia, Italy). The phenotypic and genotypic investigations on rhizobial isolates from Asinara island pasture legumes, allowed the analysis of the taxonomic position of new rhizobial strains forming efficient symbiosis with promising pasture species for the Mediterranean area. The isolates from Ornithopus compressus, Hedysarum coronarium and Scorpiurus muricatus were not closely related to currently recognized rhizobia species. Results are useful for the valorization and diffusion into cropping of wild pasture species from the Mediterranean area. The second project "Development of symbiotic systems between pasture legumes and soil microbes for restoring fertility of polluted and arid soils" was performed in the "Sardinian Geo-mining, historic and environmental Park" in the Sulcis Iglesiente area (Italy). From such area, the heavy metal tolerant strain Variovorax paradoxus 5C-2 having ACC deaminase activity was isolated, particularly efficient in subsequent experiments for plant growth promotion in the presence of toxic metal concentrations and drought. Valuable results were achieved for planning bioremediation interventions in polluted areas using symbiotic plant-microbe systems. A third project funded by the Sardinian L.R. 7, was about the "Impact of tourism and flora degradation on coastal areas of Asinara gulf and island". The microbial biodiversity was evaluated through PLFA (phospholipid fatty acid analysis) in sandy coastal areas under heavy trampling and in restricted areas. In the latter areas, the higher presence of different PLFA was associated with higher microbial biodiversity.