Symbiotic germination of a federally endangered Hawaiian endemic, Platanthera holochila (Orchidaceae), using a mycobiont from Florida: a conservation dilemma.

摘要

Platanthera holochila (Hbd.) Krzl. (Orchidaceae), one of three orchid species endemic to Hawaii, is among the rarest orchids in the world (U.S. federal endangered species, C1; global rank, G1) with ca. 18 surviving individuals. We provide a protocol for cultivating P. holochila to the leaf-bearing stage in-vitro, using a mycorrhizal fungus originally isolated from Florida (Epulorhiza repens, UAMH 9824). This study describes two separate experiments aimed at inducing leaf formation: (1) a low agar pH, and (2) an agar medium containing nutrients (e.g., MgSO4.7H2O). Seeds sown on acidified (pH 4.3) modified oats medium (MOM), containing nutrients, resulted in the highest percent germination recorded for the study (16.8%), and leaf formation (Stage 4) in up to 2.3% of the viable seed total. Also the ethics of releasing P. holochila seedlings harboring the Florida fungus into Hawaii is discussed. We advocate that such seedlings not be introduced into natural habitats in Hawaii, given the state's high number of vulnerable taxa and the potential for the fungus to further upset the ecological balance there..