Fungi play irreplaceable roles for ecosystem functioning. They may adopt different lifestyles, for example saprotrophs, symbionts or parasites: some species are cosmopolitan with a wide distribution and others, thanks to their ecological plasticity, may adapt to harsh environments precluded to most of life forms. In stressing conditions, their role is even more crucial for the recycling of organic matter or favoring nutrients uptake. When the conditions become really extreme and competition is low, fungi focus on extremotolerance and evolve peculiar competences to exploit natural or xenobiotic resources in the particular constrains imposed by the environment. This paper focuses on three different cases of fungal life in the extremes: hydrocarbon-polluted sites, extremely acidic substrates, and littoral dunes, aiming to give few but significant examples of the role of these fascinating organisms in peculiar habitats and the valuable biotechnological potentialities of the abilities they have evolved in response to such constrains. Keywords

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The antifungal properties of saponin mixtures from alfalfa (Medicago sativa L.) tops and roots, the corresponding mixtures of prosapogenins from tops, and purified saponins and sapogenins against the causal agent of rice blast Pyricularia oryzae isolates are presented. In vitro experiments highlighted a range of activities, depending upon the assayed metabolite. The antifungal effects of the most promising prosapogenin mixture from alfalfa tops were confirmed by means of in planta tests using three different Italian cultivars of rice (Oryza sativa L. ssp. japonica), known to possess high, medium, and low blast resistance. The evidenced antifungal properties of the tested metabolites allowed some considerations on their structure-activity relationship. Results indicate that prosapogenins are active compounds to prevent the fungal attack of P. oryzae on different rice cultivars. Therefore, if properly formulated, these substances could represent a promising and environmentally friendly treatment to control rice blast.

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Aims:  To study the survival in the soil and the dispersion in the environment of Trichoderma atroviride SC1 after soil applications in a vineyard. Methods and Results:  Trichoderma atroviride SC1 was introduced into soil in two consecutive years. The levels of T. atroviride populations at different spatial and temporal points following inoculation were assessed by counting the colony‐forming units and by a specific quantitative real‐time PCR. A high concentration of T. atroviride SC1 was still observed at the 18th week after inoculation. The vertical migration of the fungus to a soil depth of 0·4 m was already noticeable during the first week after inoculation. The fungus spread up to 4 m (horizontally) from the point of inoculation and its concentration decreased with the increasing distance (horizontal and vertical). It was able to colonize the rhizosphere and was also found on grapevine leaves. One year after soil inoculation, T. atroviride SC1 could still be recovered in the treated areas. Conclusions:  Trichoderma atroviride SC1 survived and dispersed becoming an integrant part of the local microbial community under the tested conditions. Significance and Impact of the Study:  The persistence and rapid spread of T. atroviride SC1 represent good qualities for its future use as biocontrol agent against soilborne pathogens.