Symbiotic seed germination and seedling growth of mycorrhizal fungi in Paphiopedilum hirsutissimun (Lindl.Ex Hook.) Stein from China

ABSTRACT

Similar to other orchid species, Paphiopedilum hirsutissimum (Lindl.ex Hook.) Stein, relies on nutrients provided by mycorrhizal fungus for seed germination and seedling development in the wild owing to a lack of endosperm in its seeds. Therefore, obtaining suitable and specialized fungi to enhance seed germination, seedling formation, and further development is considered a powerful tool for orchid seedling propagation, reintroduction, and species conservation. In this study, we investigated the diversity, abundance, and frequency of endophytic fungal strains in the root organs of P. hirsutissimum. One family and five genera of the fungi were isolated and identified through rDNA-ITS sequencing. The ability of isolated fungi to germinate in vitro from the seeds of this species was evaluated, and the development of P. hirsutissimum protocorm has been described. The findings showed that the treatments inoculated with endophytic fungal DYXY033 may successfully support the advanced developmental stage of seedlings up to stage 5. In addition, scanning electron microscopy (SEM) revealed that the mycelium of this strain began to invade from either end of the seeds up to the embryo, extending rapidly from the inside to the outside. Its lengthening resulted in the bursting of the seed coat to form protocorms, which developed into seedlings. The results showed that DYXY033 has a high degree of mycobiont specificity under in vitro symbiotic seed germination conditions and is a representative mycorrhizal fungus with ecological value for the species. In summary, this strain may particularly be significant for the protection of P. hirsutissimum species that are endangered in China. In the long run, it may also contribute to global efforts in reintroducing orchid species and in realizing in situ restorations of threatened orchid populations.

KEYWORDS:

• Paphiopedilum hirsutissimum
• mycorrhizal fungi
• symbiotic germination
• seedling development
• reintroduction

Acknowledgments

We would like to acknowledge the research funding provided by the Science and Technology Department of Guizhou Province, China.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

The datasets used or analyzed in the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

The work was supported by the  National key wildlife protection subsidy project: The Capacity Improvement Project of State Key Laboratory of Southwest Karst Mountain Biodiversity Conservation of National Forestry and Grassland Administration [2019-000411-05-01-001641]; Scientific Search Projects of Guizhou Forestry Bureau [2019] 02;Scientific Search Projects of Guizhou Forestry Bureau [2022] 36 .