Foliar fungi of the enigmatic desert plant Welwitschia mirabilis show little adaptation to their unique host plant

Martin Kemler; Michael J. Wingfield; Don A. Cowan; Bernard Slippers

doi:10.17159/sajs.2021/7666

Authors

Martin Kemler 1.Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa; 2.Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa; 3.AG Geobotanik, Ruhr University Bochum, Bochum, Germany https://orcid.org/0000-0002-0738-4233
Michael J. Wingfield 1.Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa; 2.Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa https://orcid.org/0000-0001-9346-2009
Don A. Cowan 1.Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa; 2.Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa https://orcid.org/0000-0001-8059-861X
Bernard Slippers 1.Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa; 2.Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa https://orcid.org/0000-0003-1491-3858

DOI:

https://doi.org/10.17159/sajs.2021/7666

Keywords:

Welwitschia mirabilis, Namib Desert, foliar fungi, Alternaria, Aureobasidium

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.

Open data sets*: https://www.ncbi.nlm.nih.gov/genbank

*see accession numbers in text