Interaction between protocorms of Gastrodia elata (Orchidaceae) and Mycena dendrobii in symbiotic germination

Symbiotic germination tests between seeds of Gastrodia elata and Mycena dendrobii. demonstrated M. dendrobii stimulated seed germination. Many seeds germinated and formed protocorms, which were colonized by fungal hyphae. The hyphae were commonly distributed in stipecell, subepidermal parenchyma cells (SEP) and inner cortical parenchyma cells (ICP), and were separated from protocorm cell cytoplasma by electron-lucent materials and the protocorm cell plasma membrane. The hyphae formed pelotons in SEP, but in ICP they were digested and lysed. Protocorm cells containing degenerated hyphae were frequently recolonized by hyphae, and hyphal digestion and the reinfection of protocorm cells occurred repeatedly throughout all growth course of protocorm.