STRESS SIGNALING IN EDIBLE MYCORRHIZAL FUNGI – A STEP TOWARDS UNDERSTANDING FRUCTIFICATION

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The response of Betula pubescens to inoculation with an ectomycorrhizal fungus and a plant growth promoting bacterium is substrate-dependent

Publication . Sousa, Nadine R.; Franco, Albina R.; Ramos, Miguel A.; Oliveira, Rui S.; Castro, Paula M. L.

The combination of ectomycorrhizal (ECM) fungi and plant growth promoting bacteria (PGPB) has considerable potential in forestry. Here we report on the combined effects of PGPB Mesorhizobium sp. and the ECM fungus Paxillus involutus on the growth of Betula pubescens in two different substrates, a forest soil and an alkaline anthropogenic sediment. Growth, nutrient concentration and mycorrhizal formation of B. pubescens were determined at the end of the experiment and the fungal and bacterial communities were assessed by denaturing gradient gel electrophoresis. The combined effects of ECM and PGPB enhanced root and shoot growth most in the forest soil with Mesorhizobium appearing to stimulate mycorrhizal formation. However, in the alkaline sediment, an antagonistic interaction was detected between P. involutus and Mesorhizobium sp., with Mesorhizobium sp. alone stimulating growth. The significant interaction between the ECM and the PGBP across the two substrates is discussed.

2015Journal article

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Inoculation with ectomycorrhizal fungi affects Pinus pinaster performance under cadmium exposure

Publication . Sousa, Nadine R.; Ramos, Miguel A.; Marques, Ana P. G. C.; Castro, Paula M. L.

Afforestation of contaminated sites can represent a valuable approach to restore degraded ecosystems. Studies on the response of woody species to heavy metal contamination in soil are scarce compared to crop species. Cadmium is one of the most toxic heavy metals and its hazardous effects are well known. The aim of this work was to evaluate Pinus pinaster performance on Cd contaminated soil (15 and 30 mg Cd kg-1) and determine whether inoculation with two ectomycorrhizal fungi, Suillus bovinus and Rhizopogon roseolus influenced such response. Regarding non-inoculated seedlings, Cd exposure led to a lower shoot biomass and metal accumulation on the root system was proportional to its concentration in the soil. Inoculation with S. bovinus was the most favorable treatment for P. pinaster development by enhancing shoot development up to 1.3-fold in contaminated soil. Inoculation with R. roseolus increased Cd concentration in the shoots with no significant effect in any of the biometric traits studied. Metal accumulation on the shoots and roots of P. pinaster seedlings was significantly affected by the interaction between mycorrhizal inoculation and the Cd concentration to which the seedlings were exposed. Results from this study show that inoculation with selected ECM fungi can influence the performance of P. pinaster under Cd exposure and that this biotechnological tool could be of great value for plant establishment in contaminated sites.

2014Conference object

Open access

The effect of fungal-bacterial interaction on the phenolic profile of Pinus pinea L

Publication . Araújo, Giovânia C.; Sousa, Nadine R.; Castro, Paula M. L.

Studies on the functional significance of bacteria associated with ectomycorrhizal (ECM) fungi are scarce, as well as information on the metabolism of the host plant when in symbiosis with ECM fungi. Here we intended to evaluate the phenolic profile of seedlings when associated with Bacillus subtilis (B1), Pisolithus tinctorius (Pis) and their combination (PisB1). The interaction between microorganisms was conducted in three stages: (i) in vitro evaluation of fungal/bacterial interaction, (ii) microcosms, (iii) plant transplantation to natural soil. The profile of phenolic compounds was determined at the end of stages (ii) and (iii) and further supplemented with biometric, nutritional and analysis of the ectomycorrhizal community by denaturing gradient gel electrophoresis. In the in vitro compatibility test, B1 inhibited fungal growth at all glucose concentrations tested. In the microcosm, the levels of chlorogenic and p-coumaric acid decreased over time, unlike the protocatechuic acid which tended to increase during 70 days. After transplantation to the soil, the levels of phenolic acids decreased in all treatments, while catechin increased. B. subtilis positively influenced the fungus-plant relationship as was evidenced by higher biomass of seedlings inoculated with the dual inoculum (PisB1), both in the microcosm and soil stages. The presence of the bacteria interfered in the composition of the ECM fungal community installed in Pinus pinea L. in the soil. This leads to infer that B. subtilis may have caused a greater effect on the metabolism of P. pinea, especially in synergy with mycorrhizal fungi, than the action of the isolated fungus.

2018Journal article

Restricted access