Orchid Reintroduction Based on Seed Germination-Promoting Mycorrhizal Fungi Derived From Protocorms or Seedlings

Abstract

Orchids are among the most endangered in the plant kingdom. Lack of endosperm in their seeds renders orchids to depend on nutrients provided by orchid mycorrhizal fungi (OMF) for seed germination and seedling formation in the wild. OMF that parasitize in germination seeds is an essential element for orchid seedling formation, which can also help orchid reintroduction. Considering the limitations of the previous orchid reintroduction technology based on seed germination-promoting OMF (sgOMF) sourced from orchid roots, an innovative approach is proposed here in which orchid seeds are directly co-sown with sgOMF carrying ecological specificity from protocorms/seedlings. Based on this principle, an integrative and practical procedure concerning related ecological factors is further raised for re-constructing long-term and self-sustained orchid populations. We believe that this new approach will benefit the reintroduction of endangered orchids in nature.

Isolation and identification of beneficial orchid mycorrhizal fungi in Paphiopedilum barbigerum (Orchidaceae)

“…Thus, nearly all orchid species rely on a symbiotic relationship with fungi for seed germination and protocorm development. 3 Depending on the presence of functional fungi in cortical cells, orchid fungi are classified as mycorrhizal and nonmycorrhizal fungi. 4 Mycorrhizal fungi (soil saprotrophs), 5 such as Ceratobasidiaceae, Tulasnellaceae , and Sebacinaceae , are collectively referred to as Rhizoctonia ; they increase seed germination as well as the development rate of protocorm and seedlings of orchids.…”

The challenges of growing orchids from seeds for conservation: An assessment of asymbiotic techniques

“…This study demonstrates the great potential in combining asymbiotic and symbiotic techniques to grow native orchids from seeds, but, as noted by the authors, environmental and horticultural conditions must be considered for both orchids and fungi to establish long‐lasting symbioses important to orchid health. Finally, there is also a need to better understand turnover in mycorrhizal partners as mycorrhizae of protocorms and adult orchids can vary and may influence how young seedlings respond to environmental conditions (McCormick et al, 2021 ; Zhao et al, 2021 ).…”

“…In vitro symbiotic germination has been used for orchid propagation (Pujasatria et al, 2020 ), however, successful propagation requires extensive knowledge of the specific orchid–mycorrhizal interaction, as well as the ability to isolate and grow the fungus, which can take considerable time and effort. Mycorrhizae isolated from the roots of mature plants may not be suitable for inducing seed germination (McCormick et al, 2021 ; Zhao et al, 2021 ), and many orchid mycorrhizal fungi are unculturable axenically, making symbiotic germination impossible (Li et al, 2021 ). By contrast, germination of orchid seeds on artificial medium without mycorrhizae, or asymbiotic germination, could be a more time‐ and cost‐efficient means of propagating orchids.…”

Characterization of a Plant Growth-Promoting Endohyphal Bacillus subtilis in Fusarium acuminatum from Spiranthes sinensis

“…It can be used for inflammatory, cancer, diabetic, and other diseases (Gutiérrez 2010;Shie et al 2015). Because the tiny seeds lack endosperm for successful germination and seedling growth, the orchids, including S. sinensis, require an association with endophytic fungi (Zhao et al 2021). Endophytic fungi enhance nutrient availability to orchid roots and help them survive even upon exposure to pathogens (Sarsaiya et al 2019).…”