Journal article
Signatures of recombination in clonal lineages of the citrus brown spot pathogen, Alternaria alternata sensu lato
Phytopathology, Vol.103(7), pp.741-749
07/2013
Handle:
https://hdl.handle.net/2376/108602
PMID: 23441968
Abstract
Most Alternaria spp. are considered asexual but recent molecular evolution analyses of Alternaria mating-type genes show that the mating locus is under strong purifying selection, indicating a possible role in sexual reproduction. The objective of this study was to determine the mode of reproduction of an Alternaria alternata sensu lato population causing citrus brown spot in central Florida. Mating type of each isolate was determined, and isolates were sequenced at six putatively unlinked loci. Three genetically distinct subpopulations (SH1, SH4A, and SH4B) were identified using network and Bayesian population structure analyses. Results demonstrate that most subpopulations of A. alternata associated with citrus are clonal but some have the ability to extensively recombine through a cryptic sexual cycle or parasexual cycle. Although isolates were sampled in close physical proximity (≈2,500-m² area), we were able to reject a random mating model using multilocus gametic disequilibrium tests for two subpopulations, SH1 and SH4B, suggesting that these subpopulations were predominantly asexual. However, three recombination events were identified in SH1 and SH4B and localized to individuals of opposite mating type, possibly indicating meiotic recombination. In contrast, in the third subpopulation (SH4A), where only one mating type was present, extensive reticulation was evident in network analyses, and multilocus gametic disequilibrium tests were consistent with recombination. Recombination among isolates of the same mating type suggests that a nonmeiotic mechanism of recombination such as the parasexual cycle may be operating in this subpopulation. The level of gene flow detected among subpopulations does not appear to be sufficient to prevent differentiation, and perhaps future speciation, of these A. alternata subpopulations.
Metrics
12 Record Views
Details
- Title
- Signatures of recombination in clonal lineages of the citrus brown spot pathogen, Alternaria alternata sensu lato
- Creators
- Jane E Stewart - Department of Plant Pathology, Washington State University, Pullman, USA. stewart@science.oregonstate.eduKalyn A ThomasChristopher B LawrenceHa DangBarry M PryorL M Pete TimmerTobin L Peever
- Publication Details
- Phytopathology, Vol.103(7), pp.741-749
- Academic Unit
- Plant Pathology, Department of
- Publisher
- United States
- Identifiers
- 99900547493401842
- Language
- English
- Resource Type
- Journal article