Suitable fungi are needed to induce successful germination of orchid seeds. However, only a few studies have recently focused on fungi that were isolated from protocorms, especially from the host plant. 

In a study published in Mycorrhiza, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) investigated how fungi isolated from protocorms of the endangered epiphytic orchid, Dendrobium chrysotoxum (an epiphytic orchid species that grows on tree trunks or as a lithophyte on rocks), and three related Dendrobium species affected seed germination and seedling development under in vitro conditions. 

The researchers conducted symbiotic seed germination experiments for 90 days under different light conditions with fungal strains isolated from protocorms of D. chrysotoxum and three sister species. 

In situ baiting resulted in successful protocorm formation and allowed isolation of mycorrhizal fungi for in vitro germination experiments. Three out of four fungal isolates from host protocorms were typical of orchid mycorrhizal associations and able to induce protocorm and seedling formation. 

The results showed that both light conditions and the identity of fungal strains had a strong effect on in vitro seed germination and seedling growth, with fungi isolated from host protocorms leading to accelerated germination and seedling formation. 

"From a practical point of view, we recommend using fungal strains isolated from host protocorms to propagate seedlings and to set up reintroduction in the field for orchid conservation and restoration," said Dr. SHAO Shicheng, first author of the study. 

Dendrobium chrysotoxum in full bloom. (Image by SHAO Shicheng)