Fungal diversity associated with the mycorrhizosphere soil of Brachycorythis conica subsp. transvaalensis, a critically endangered and endemic terrestrial orchid from South Africa

DATA ACCESSIBILITY : The high-throughput sequencing data generated in this study is available at the NCBI Sequence Read Archive (https://submit.ncbi.nlm.nih.gov/ subs/sra/) under the accession number PRJNA693177.The Albertina Sisulu orchid, Brachycorythis conica subsp. transvaalensis is a critically endangered terrestrial orchid with a single population remaining in the Gauteng Province of South Africa. For the conservation of this endemic orchid, several strategies are being implemented such as protection of habitat, identifying pollinators and in vitro propagation. For symbiotic germination, it is essential to identify the mycorrhizal associates of this orchid using non-destructive sampling. In this study, high-throughput sequencing was used to catalogue and compare the diversity of fungi associated with the mycorrhizosphere of this orchid and non-mycorrhizosphere soils collected from the same coordinates. Bioinformatics and statistical analyses of the data showed that, despite the substantial overlap in the community composition of fungi associated with these two soil types, several exclusive fungal species were identified from the mycorrhizosphere of the orchid. These included an assortment of potential orchid mycorrhizal species from the orders Agaricales, Cantharellales and Sebacinales. This study provides the first insight into the soil fungal diversity associated with the mycorrhizosphere of this critically endangered orchid. In the future, data from this study can be used for optimising conservation measures and isolation of suitable mycorrhizal species required for in vitro symbiotic germination of this orchid.The NRF Foundational Biodiversity Information Programme, the International Partnergroup Program of the Max Planck Society and the NRF SARChI Chair in Fungal Genomics.http://www.elsevier.com/locate/sajbhj2023BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant PathologyZoology and Entomolog

Uncovering the mycorrhizal community of two Habenaria orchids in South Africa

Southern Africa is a biodiversity hotspot for a variety of orchids, including Habenaria. However, we know very little about the orchid mycorrhizae that are associated with these orchids. To bridge this gap, we compared the community of orchid mycorrhizae that are associated with two indigenous Habenaria species, H. barbertoni and H. epipactidea, using a high-throughput sequencing platform. We selected these two orchids because their distribution zones overlap in South Africa. Furthermore, H. barbertoni is endangered, whereas H. epipactidea is not. We hypothesised that the mycorrhizal diversity and composition linked with the roots of these two orchids would overlap, but that some distinct fungal taxa would exist, and these distinct fungi would include unusual taxa. Analyses of the DNA sequence data revealed that the two orchids shared 35 fungal OTUs. Twenty-four and seventeen OTUs were exclusively detected in the roots of H. barbertoni and H. epipactidea, respectively. Mycorrhizal fungi from the rust lineage Atractiellales (Atractiellomycetes, Pucciniomycotina) were only detected in the roots of the endangered H. barbertoni, which represents the first report of these fungi associated with orchids outside of the Andean rainforest. Our findings increase knowledge of the diversity of mycorrhizae associated with indigenous orchids on the African continent.The South African National Research Foundation, the Max Planck Society's International Partnergroup Program and National Research Foundation SARChI Chair in Fungal Genomics.http://www.elsevier.com/locate/sajbhj2023BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant PathologyZoology and Entomolog