Raw data for article "Effect of truffle-associated bacteria and fungi on the mycorrhi-zation of Quercus ilex seedlings with Tuber melanosporum"

The success of truffle cultivation depends especially on the quality of mycorrhizal seedlings, which are typically produced under aseptic conditions to avoid contamination by unwanted fungi. However, such practices may also eliminate beneficial microorganisms that could support truffle symbiosis, improving seedling quality and enhancing field establishment of truffle plantations. In this study, a set of 12 endophytic bacteria and fungi isolated from the Tuber melanosporum environment (gleba tissue, mycorrhizae and truffle brûlé) was tested on Quercus ilex seedlings under nursery conditions. Co-inoculation with a strain of Agrobacterium tumefaciens significantly enhanced root colonization by T. melanosporum and exhibited in vitro plant growth-promoting traits, supporting its potential role as mycorrhizal helper bacterium. In contrast, a strain of Trichoderma harzianum negatively affected mycorrhization. None of the tested strains showed significant effects on seedling growth. Our findings support the hypothesis that specific bacterial strains associated with truffles can act as mycorrhizal helper bacteria, highlighting their potential for co-inoculation strategies to enhance quality of truffle seedlings in nurseries. However, most of the tested microorganisms did not show a significant effect on seedling mycorrhization or growth, underscoring the need for further research to better understand the interactions within the mycorrhizosphere, in order to improve seedling quality.