The influence of plant co-culture of tomato plants with Piriformospora indica on biomass accumulation and stress tolerance.

In the face of increasing demand for crop production and the detrimental environmental impact of the excessive use of fertilizers it is important to use all available tools to increase crop nutrient use, efficiency and quality. Nutrient acquisition by the plant roots is much influenced by the microbial composition and activity of the rhizosphere. Most crop plants (80%) form symbiotic associations with arbuscular mycorrhizal fungi. However, these fungi are obligatory biotrophs, and therefore cannot be cultivated without the plants. Piriformospora indica is a recently discovered endophyte that mimics many of the effects of arbuscular mycorrhizal fungi but can be cultivated in axenic cultures. The aim of our work was to evaluate the effects of the co-culture of Piriformospora indica with tomato (Solanum lycopersicum 'Roma') plants in respect to plant response to stress and production quality. Results show that P. indica is able to promote resistance to stress (salt and nutrient) through the activation of antioxidant metabolism, which leads to the accumulation of ascorbate (vitamin C). Fruits of plants inoculated with P. indica maintain their lycopene content independently of the growth conditions.