Recovery of mycorrhizal fungi from wild collected protocorms of Madagascan endemic orchid Aerangis ellisii (B.S. Williams) Schltr. and their use in seed germination in vitro

Abstract

Orchid mycorrhizal fungi (OMF) are critical for seed germination and maintaining natural populations of orchids, yet the degree of specificity of most orchids to their mycorrhizal associates remains unknown. Many orchids are at risk of extinction, whether generalists or specialists, but orchid species of narrow fungal specificity are arguably under increased threat due to their requirement for specific fungal symbionts. This study characterises the fungi associated with Aerangis ellisii , a lithophytic orchid from a site in the Central Highlands of Madagascar. Culturable OMF isolated from spontaneous protocorms of this species from the wild were used for seed germination. In vitro germination and seedling development of A. ellisii were achieved with fungi derived from A. ellisii and an isolate from a different Aerangis species 30 km away. The significance of these findings and their importance to conservation strategies for this species and other Aerangis spp. is discussed. These results have important implications for the conservation of A. ellisii populations in Madagascar.

The Diverse Assemblage of Fungal Endophytes from Orchids in Madagascar Linked to Abiotic Factors and Seasonality

“…Habenaria quartziticola (T) * Aerangis ellisii seeds were germinated by Cer2 and Cer3 (from Aerangis sp. ), as reported by Kendon et al [25]. ** Cynorkis purpurea seeds were germinated better by non-Cynorkis orchid mycorrhizal fungi than own mycorrhizal fungus (ser1), as reported by Rafter et al [24].…”

Preventing Extinction of the Critically Endangered Dactylorhiza incarnata subsp. ochroleuca in Britain Using Symbiotic Seedlings for Reintroduction

“…Putative mycorrhizal fungi from protocorms [ 36 ] or seedlings [ 37 , 38 ] serve as reliable symbionts for seed germination. In some cases, the orchid seeds can only be germinated by a specific lineage of the mycorrhizal fungus from protocorms [ 35 ].…”

“…Additionally, identifying the mycorrhizal fungal diversity and abundance using the qPCR method offers quick and reliable information on the suitability of the proposed reintroduction/translocation site. Understanding the symbiotic behavior of orchids to produce seedlings that are suitable for augmenting in the wild is an important aspect in addition to protecting plants in the wild as studied in orchids of Madagascar [ 26 , 36 ]. Following the successful establishment of plants after reintroduction applying different tools such as qPCR to identify fungi at different seasons will help understand the fungal recruitment behavior and resilience of plants.…”

Fungal Diversity of Selected Habitat Specific Cynorkis Species (Orchidaceae) in the Central Highlands of Madagascar

“…For example, of its estimated 10,000 vascular plant species, 90% are found nowhere else on earth [ 13 ] and this is also true of 1000 orchid species within 57 genera [ 14 ]. Given that 90% of Madagascar’s original vegetation has been cleared or permanently altered, many orchid populations throughout the country have been reduced in size to fragmented patches where seedling recruitment is generally low [ 15 ], possibly due to inbreeding depression [ 16 ]. Nevertheless, these forest remnants still support a surprisingly diverse orchid flora.…”