Mycorrhizal synthesis of Tuber indicum with two indigenous hosts, Castanea mollissima and Pinus armandii.

Tuber indicum is one of the most renowned commercialized fungi in China. Mycorrhizal investigations, however, have been carried out mainly with exotic trees. Up to now there is no detailed description of morphology of the mycorrhizae formed with the indigenous hosts of T. indicum. Containerized seedlings of two indigenous hosts of the fungus in southwestern China, Pinus armandii and Castanea mollissima, were inoculated with aqueous spore suspension of T. indicum in two kinds of substrates. Mycorrhizae began to form 4 months after inoculation and were harvested at 9 months. The contributing fungus of the mycorrhizae was confirmed to be T. indicum by morphological and ITS-rDNA sequence analyses. The morphology of emanating hyphae and epidermoid-like mantle appearance was similar to the mycorrhizae obtained with some European trees. The high morphological variation and the similarity to that of Tuber melanosporum makes it difficult to distinguish the mycorrhizae of the two species by morphology alone. The synthesis of mycorrhizae of T. indicum with its indigenous hosts will be of great significance for planned cultivation of the Asian black truffles.