Techniques for Host Plant Inoculation with Truffles and Other Edible Ectomycorrhizal Mushrooms

Abstract

Large-scale production of high-quality mycorrhizal plants in the greenhouse is mainstay for the modern cultivation of edible ectomycorrhizal mushrooms (EEMMs). Success at this step not only depends on the reliability of the fungal inoculum used for plantlet mycorrhization but also on the environmental conditions attending symbiosis establishment. Methods developed 40–50 years ago for inoculating host plants with EEMMs are still largely used today, with slight modifications. Mycelial inoculations are used commercially only for some edible ectomycorrhizal (EEM) basidiomycetes, while inoculation with spores is the most common method for producing seedlings colonized with truffle mycorrhizas. However, pure cultures and ectomycorrhizas of Tuber have also been used to obtain mycorrhizal plants mainly for scientific purposes. Mycelium-based inoculum offers many advantages, such as lower contamination risks and more reliable root colonization and provides opportunities for genetic selection of EEMM strains. The long-time preservation of EEM cultures and the creation of germ plasm banks would be an important step to support mycelium-based technologies. To this aim, we demonstrate successful cryopreservation of strains of Tuber borchii and Tuber aestivum. Recent advances in genetics and biotechnology of EEMs and their hosts have the potential to transform the current EEMM nursery trade.