Edible ectomycorrhizal fungi and Cistaceae. A study on compatibility and fungal ecological strategies

Wild edible mycorrhizal mushrooms are among the most appreciated and prized mushrooms in the world. Despite the cultivation of ectomycorrhizal (ECM) mushrooms has been a growing subject of study worldwide, it has been hampered by the mutualistic lifestyle of the fungi. Although not being obligate symbionts, most of the species of ECM mushrooms only produce fruit bodies in association with trees or shrubs. In the present study, we aimed at understanding certain aspects of the ecology of four different edible ECM fungi: Lactarius deliciosus, Tricholoma equestre, T. portentosum and Boletus fragrans. Despite having a broad distribution worldwide, these fungi inhabit also Mediterranean habitats with understories typically dominated by rockroses (Cistaceae). Studying the ecology of these mutualistic fungi as well as the interaction with these species of shrubs is not only scientifically relevant but also pivotal for the discovery of profitable cultivation protocols. We evaluated the compatibility of these ECM species with five species within Cistaceae family - Cistus ladanifer, C. psilosepalus, C. salviifolius, Halimium halimifolium and Tuberaria lignosa. Each species of fungi proved to be able to establish mycorrhizas with at least 2 different plants species but varied in their host range of the tested Cistaceae. The dissimilarity in terms of host specificity between some fungal species seemed to be connected with the phylogenetic distances of the fungi. A correlation between the colonization percentage of the root systems and the mycelial growth rates in pure culture was found. The connection of these traits might be an important key to understanding the ecological competitor-colonizer tradeoffs of these ECM fungal species. Altogether, our study reports unknown plant-fungi combinations with economical relevance and also adds new insights about the ecology of these species of ECM fungi.

野生食用外生菌根（ectomycorrhizal, ECM）蘑菇是全球最受推崇与珍视的蘑菇品类之一。尽管外生菌根（ECM）蘑菇的培育研究在全球范围内持续升温，却因该类真菌的共生生活型而遭遇瓶颈。尽管多数外生菌根蘑菇物种并非专性共生菌，但它们通常仅在与乔木或灌木形成共生关系时才会产生子实体。本研究旨在解析4种食用外生菌根真菌的部分生态学特征，分别为美味乳菇（Lactarius deliciosus）、黄绿杯伞（Tricholoma equestre）、粗壮口蘑（Tricholoma portentosum）与香牛肝菌（Boletus fragrans）。尽管这些真菌在全球分布范围广泛，却同样栖息于以岩蔷薇（半日花科Cistaceae）为优势下层植被的地中海生境中。探究这类共生真菌的生态学特征及其与这类灌木的互作关系，不仅具有重要的科学价值，同时也为开发具有经济效益的培育方案提供了关键支撑。本研究评估了这4种外生菌根真菌与半日花科5种植物的共生兼容性，涉及的植物分别为腺毛岩蔷薇（Cistus ladanifer）、细萼岩蔷薇（Cistus psilosepalus）、鼠尾草叶岩蔷薇（Cistus salviifolius）、半日花（Halimium halimifolium）以及木根草（Tuberaria lignosa）。实验结果显示，每种真菌均能与至少2种供试的半日花科植物形成菌根，但不同真菌的宿主范围存在差异。部分真菌物种间的宿主特异性差异，似乎与真菌的系统发育距离存在关联。研究还发现，植物根系的菌根定殖率与纯培养条件下真菌的菌丝生长速率之间存在相关性。这些性状间的关联，或许是理解这类外生菌根真菌竞争-定殖生态权衡关系的关键所在。综上，本研究报道了一批具有经济价值的全新植物-真菌共生组合，并为这类外生菌根真菌的生态学研究提供了新的认知。