Serendipita Promotes Seed Germination and Seedling Development of the Endangered Orchid Mengzia Foliosa under in Vitro Conditions

Mycorrhizal fungi are a critical ecological determinant for the survival and population sustainability of orchids, playing a decisive role in the success of conservation efforts for endangered species. However, the symbiotic relationship during the early life stages of the rare terrestrial orchid Mengzia foliosa remains unexplored. To address this knowledge gap, we investigated the mycorrhizal associations during the germination and seedling development of M. foliosa. Ten fungal strains, four isolated from the roots of Bletilla striata (MB-11, MB-13, MB-15 and MB-18) and six isolated from the protocorms of M. foliosa (MH1-A, MH1-B, MH1-E, MH3-2-A, MH4-2-A and MH4-B), were co-cultured with M. foliosa seeds in vitro for 16 weeks. Six fungal strains significantly promoted seed germination, while four strains (MH1-A, MB-15, MH4-B, and MB-13) markedly enhanced seedling development, with MH1-A showing the highest efficacy (76.50