title: Independent origins and incipient speciation among host-associated populations of Thielaviopsis ethacetica in Cameroon.
abstract: Thielaviopsis ethacetica was recently reinstated as a distinct taxon using DNA phylogenies. It is widespread affecting several crop plants of global economic importance. In this study, microsatellite markers were developed and used in conjunction with sequence data to investigate the genetic diversity and structure of Th. ethacetica in Cameroon. A collection of 71 isolates from cacao, oil palm, and pineapple, supplemented with nine isolates from other countries were analysed. Four genetic groups were identified. Two of these were associated with oil palm in Cameroon and showed high genetic diversity, suggesting that they might represent an indigenous population of the pathogen. In contrast, the remaining two groups, associated with cacao and pineapple, had low genetic diversity and, most likely, represent introduced populations. There was no evidence of gene flow between these groups. Phylogenetic analyses based on sequences of the tef1-α as well as the combined flanking regions of six microsatellite loci were consistent with population genetic analyses and suggested that Th. ethacetica is comprised of two divergent genetic lineages.
authors.affiliation: Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), Private Bag X20 Hatfield, University of Pretoria, Pretoria 0028, South Africa.
authors.forename: Michael
authors.initials: M
authors.lastname: Mbenoun
authors.affiliation: Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), Private Bag X20 Hatfield, University of Pretoria, Pretoria 0028, South Africa.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wingfield
authors.affiliation: Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), Private Bag X20 Hatfield, University of Pretoria, Pretoria 0028, South Africa.
authors.forename: Teboho
authors.initials: T
authors.lastname: Letsoalo
authors.affiliation: Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), Private Bag X20 Hatfield, University of Pretoria, Pretoria 0028, South Africa; Agricultural Research Council-Vegetable and Ornamental Plant Institute (ARC-VOPI), Private Bag X293, Pretoria 0001, South Africa.
authors.forename: Wubetu
authors.initials: W
authors.lastname: Bihon
authors.affiliation: Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), Private Bag X20 Hatfield, University of Pretoria, Pretoria 0028, South Africa.
authors.forename: Brenda D
authors.initials: BD
authors.lastname: Wingfield
authors.affiliation: Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), Private Bag X20 Hatfield, University of Pretoria, Pretoria 0028, South Africa. Electronic address: jolanda.roux@fabi.up.ac.za.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Roux
mesh_terms: D031230:Ananas / Q000382:microbiology; D028023:Arecaceae / Q000382:microbiology; D001203:Ascomycota / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D002099:Cacao / Q000382:microbiology; D002163:Cameroon; D014644:Genetic Variation; D005838:Genotype; D018895:Microsatellite Repeats; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D020648:Peptide Elongation Factor 1
keywords: Anthropogenic dispersal; Cryptic species; Genealogical concordance; Host-associated differentiation; Species concepts