Tuber melanosporum drives the symbiosis with Castanea sativa seedlings under greenhouse conditions and high calcium levels

The sweet chestnut (Castanea sativa) could potentially be used as a host for the Perigord truffle (Tuber melanosporum) in multi-cropping plantations to promote rural or marginalized economies by providing farmers with a valuable source of income from both the truffle and the chestnut. Black truffles are known to associate to sweet chestnut trees in the wild. However, inoculation of chestnut seedlings with this highly appreciated edible fungus has not been attempted so far under greenhouse conditions. In this study, we tested the suitability of C. sativa as a host for T. melanosporum using a substrate containing high levels of active calcium (Ca2+) to enhance truffle growth. We found that C. sativa seedlings can be successfully colonized by T. melanosporum in the nursery and that T. melanosporum appears to have a strong influence in its host's physiology, growth, and nutritional processes. The inoculated plants showed a greater root dry weight, water potential values and higher Ca2+ content. Under these conditions and using a substrate containing limestone seems to favour the fungus in the mutualistic symbiosis.

Automated summary

The study found that using a substrate with high levels of active calcium can enhance the adaptation of chestnut seedlings to black truffles and promote mutualistic symbiosis between the two. Inoculated chestnut plants showed higher root dry weight, water potential values, and calcium content, indicating a positive effect of the truffle on the host plant.