Metabarcoding reveals southern hemisphere fungal endophytes within wood of cultivated Proteaceae in Portugal

Endophytic fungal hitch-hikers have been difficult to detect in the past, and have potentially spread these latent pathogens via the global plant trade. The African genera Protea, Leucospermum and Leucadendron, commercially referred to as proteas, form the basis of a global flower production industry. The largest producers of proteas are Australia and South Africa, followed by Portugal and Spain. In the 1990s propagation material from South Africa was used to establish protea orchards in Portugal. We utilized metabarcoding to determine if this plant trade has carried host-specific fungal pathogens to a new environment. Wood samples collected from asymtomatic twigs from Portuguese farms, where propagation material had been imported from South Africa, was compared to material from South African farms that originally produced and supplied rooted and unrooted cuttings. DNA metabarcoding, using fungal-specific primers for the ITS2 gene region, produced 1237 OTUs. Focusing only on known pathogens of protea, we found that the Portuguese orchards contained fungal disease agents associated with Proteaceae or other plant families from the Southern Hemisphere. Our sampling technique could be used by agencies and applied to other plant material and pathogens to reduce the spread of pathogens.