Population diversity and genetic structure reveal patterns of host association and anthropogenic impact for the globally important fungal tree pathogen Ceratocystis manginecans

Species in the Ceratocystis manginecans complex are important fungal pathogens of plantation trees globally. The most important hosts include species of Eucalyptus, Acacia, Mangifera, and Punica. Despite their relevance and widespread occurrence, little is known regarding their population genetics and how this might relate to their host associations or geographic regions in which they occur. A global collection of 491 isolates representing the C. manginecans complex, from four different plant hosts and nine countries, were genotyped using microsatellite markers. Population genetic analyses using numerous tools were conducted to interrogate how their genetic diversity and structure might be affected by host or areas of occurrence. Results of genetic diversity studies showed that when grouping isolates into populations based on their host associations, the population on Eucalyptus was most diverse, and it also has a broad global distribution. When considering countries of origin as a basis for defining populations, the gene and genotypic diversity were highest in populations from China, Indonesia, and Brazil. In contrast, populations from Oman and Pakistan collected from Mangifera had the lowest genetic diversity and were clonal. Molecular variance, population differentiation, and network and structure analyses showed that the genetic structure of isolates in the C. manginecans complex is influenced by both host association as well as geographical isolation. Furthermore, the results reflected the movement of genotypes between plant hosts and geographic regions that have implications regarding the broad global distribution of this pathogen.SUPPLEMENTARY MATERIAL: Figure S1. Linkage disequilibriumtesting (IA, p-values > 0.01). Table S1. List of Ceratocystis isolates included in the microsatellite study and the alleles scored at each locus using GeneScanTM fragment analyses and the GeneMapperTM software. Table S2. List of Ceratocystis isolates included in the microsatellite study and the alleles scored at each locus based on results obtained by sequencing. Table S3. GenBank numbers of alleles sequenced in this study.The National Key R&D Program of China (China-South Africa Forestry Joint Research Centre Project), the National Ten-thousand Talents Program, the GuangDong Top Young Talents Program, the Tree Protection Co-operative Programme (TPCP) and the National Research Foundation (NRF), South Africa.https://www.mdpi.com/journal/jofam2022BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant Patholog