Nutrients and fungal identity affect the outcome of symbiotic germination in Bipinnula fimbriata (Orchidaceae)
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Date
2020-10-21
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Abstract
Orchids produce small seeds with no energy reserves, relying entirely on orchid mycorrhizal fungi (OMF) for germination. This
process, known as symbiotic germination, can lead to different outcomes depending on abiotic factors, such as nutrient availability.
Previous studies have shown that nutrient addition has a negative effect on the outcome of symbiotic germination.
However, if this effect varies across OMF species, and if it is related to a fungal response to nutrients, remains unknown. This
paper examines the effect of fungal identity and nutrient addition (nitrogen and phosphorus) on the germination of the orchid
Bipinnula fimbriata using seven OTUs of mycorrhizal fungi from the families Tulasnellaceae and Ceratobasidiaceae. We also
evaluated the effect of nutrient addition on mycorrhizal fungi growth rates. Results showed that the nutrient effect on symbiotic
germination varied depending on fungal identity. While there was a strong negative effect on symbiotic germination with all
Tulasnella OTUs and two Ceratobasidium OTUs, less or no effectwas observed on the other two Ceratobasidium OTUs. Further
studies are needed to understand the mechanism underlying this variation and how variable is the effect of nutrient addition on
symbiotic germination in Orchidaceae and OMF species.
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Keywords
Bipinnula, Fungal identity, Symbiosis outcome, Nutrient addition, Orchidaceae, Orchid mycorrhiza, Symbiotic germination