Abstract:
Foliar fungi, especially endophytic fungi, constitute an important part of the microbiome of plants. Yet little
is known about the composition of these communities. In this study, we isolated fungi from leaf tissues of
the desert plant Welwitschia mirabilis to determine the culturable diversity of the foliar fungal community.
The isolated fungal taxa, which grouped into 17 distinct lineages, were identified by sequencing elongation
factor 1 alpha, beta-tubulin 1, beta-tubulin 2 and the internal transcribed spacer region. The culturable
community was mainly composed of cosmopolitan fungal genera despite the unique taxonomic
position of the plant and its geographic isolation. To test for endemism in two of the common
fungal genera, Alternaria and Aureobasidium, we built haplotype networks using a global data set. Even
this broad data set showed little evidence for specialisation within this unique host or its geographical
location. The data suggest that the culturable members of communities of leaf-associated fungi in
habitats with little plant coverage, such as the Namib Desert, are mainly established by long-distance
aerially distributed fungal inocula and few of these taxa co-evolve with the host within the habitat.
SIGNIFICANCE :
• The culturable members of fungal communities associated with an ecological and evolutionary isolated
plant have not co-speciated with their hosts, but to a large extent are composed of globally distributed
fungal species.
• Harsh environmental conditions and the geographic isolation of host plants seem to favour ubiquitous
fungal species over more specialist fungal species.
