Host Plants Associated with Tricholoma matsutake and Closely Allied Species in Asia

摘要

Tricholoma matsutake (matsutake) in Japan, Korea and northeastern China grows mostly in Pinus densiflora forests and is generally considered to be highly host specific. However, matsutake in southwestern China is mainly found in mixed broadleaf/pine forests. In mixed forests, the dominant tree species in the forest vegetation have been assumed to be the host plants of matsutake without precise verification by inspections of the mycorrhizal roots. We identified the host plants associated with matsutake and closely allied species growing in Asia based on detailed microscopic inspection of the roots to determine host-fungus specificity. In southwestern China, matsutake growing at about 2 000-2 800 m was predominantly associated with Castanopsis,Lithocarpus and occasionally Pinus. Matsutake growing at a high elevation of about 3 000-3 800 m in southwestern China and Bhutan was predominantly associated with evergreen sclerophyllous oaks (alpine oaks, Quercus sect. Heterobalanus) such as Q. aquifolioides and Q. semecarpifolia, although matsutake found in Shangrila, Yunnan was associated with P. densata. T. fulvocastaneum growing in Laos was associated with Castanopsis and Lithocarpus. Quercus sect. Heterobalanus distributed from the eastern Himalayas to southwestern China is considered to originate in subtropical broadleaf forests and to have evolved concurrently with uplift in the Himalayas. The ancestral matsutake would have been associated originally with Castanopsis, Lithocarpus and the evergreen sclerophyllous oaks in the subtropical region of southwestern China before the uplift of the Himalayas. Thereafter, in the higher mountainous region, matsutake associated entirely with xerophytic evergreen alpine oaks adapted to the environmental change, i. e., dry, cold climates. Matsutake associated with broadleaf trees would later have associated with Pinus and shifted to dual broadleaf/Pinus associations in the mixed forests. Pinus-associated matsutake switched hosts from broadleaf to Pinus during migration from southwestern China to northeastern China,the Korean Peninsula and Japan.