Inferring outcrossing in the homothallic fungus Sclerotinia sclerotiorum using linkage disequilibrium decay

R N Attanayake; V Tennekoon; D A Johnson; L D Porter; L del Río-Mendoza; D Jiang; W Chen

doi:10.1038/hdy.2014.37

Back

Inferring outcrossing in the homothallic fungus Sclerotinia sclerotiorum using linkage disequilibrium decay

Journal article

Open access

Peer reviewed

Inferring outcrossing in the homothallic fungus Sclerotinia sclerotiorum using linkage disequilibrium decay

R N Attanayake, V Tennekoon, D A Johnson, L D Porter, L del Río-Mendoza, D Jiang and W Chen

Heredity, Vol.113(4), pp.353-363

10/2014

DOI: https://doi.org/10.1038/hdy.2014.37

Handle:

https://hdl.handle.net/2376/105227

PMCID: PMC4181068

PMID: 24781807

Files and links (1)

url

https://doi.org/10.1038/hdy.2014.37View

Published (Version of record) Open

Abstract

Genetic Variation

Ascomycota - physiology

Hybridization, Genetic

Recombination, Genetic

Ascomycota - genetics

Microsatellite Repeats

Linkage Disequilibrium

The occurrence and frequency of outcrossing in homothallic fungal species in nature is an unresolved question. Here we report detection of frequent outcrossing in the homothallic fungus Sclerotinia sclerotiorum. In using multilocus linkage disequilibrium (LD) to infer recombination among microsatellite alleles, high mutation rates confound the estimates of recombination. To distinguish high mutation rates from recombination to infer outcrossing, 8 population samples comprising 268 S. sclerotiorum isolates from widely distributed agricultural fields were genotyped for 12 microsatellite markers, resulting in multiple polymorphic markers on three chromosomes. Each isolate was homokaryotic for the 12 loci. Pairwise LD was estimated using three methods: Fisher's exact test, index of association (IA) and Hedrick's D'. For most of the populations, pairwise LD decayed with increasing physical distance between loci in two of the three chromosomes. Therefore, the observed recombination of alleles cannot be simply attributed to mutation alone. Different recombination rates in various DNA regions (recombination hot/cold spots) and different evolutionary histories of the populations could explain the observed differences in rates of LD decay among the chromosomes and among populations. The majority of the isolates exhibited mycelial incompatibility, minimizing the possibility of heterokaryon formation and mitotic recombination. Thus, the observed high intrachromosomal recombination is due to meiotic recombination, suggesting frequent outcrossing in these populations, supporting the view that homothallism favors universal compatibility of gametes instead of traditionally believed haploid selfing in S. sclerotiorum. Frequent outcrossing facilitates emergence and spread of new traits such as fungicide resistance, increasing difficulties in managing Sclerotinia diseases.

Metrics

11 Record Views

Details

Title: Inferring outcrossing in the homothallic fungus Sclerotinia sclerotiorum using linkage disequilibrium decay
Creators: R N Attanayake - Department of Plant Pathology, Washington State University, Pullman, WA, USA
V Tennekoon - Department of Economics, University of Oklahoma, Norman, OK, USA
D A Johnson - Department of Plant Pathology, Washington State University, Pullman, WA, USA
L D Porter - USDA-ARS, Vegetable and Forage Crops Research Unit, Prosser, WA, USA
L del Río-Mendoza - Department of Plant Pathology, North Dakota State University, Fargo, ND, USA
D Jiang - Department of Plant Protection, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China
W Chen - 1] Department of Plant Pathology, Washington State University, Pullman, WA, USA USDA-ARS, Grain Legume Genetics and Physiology Research Unit, Pullman, WA, USA
Publication Details: Heredity, Vol.113(4), pp.353-363
Academic Unit: Plant Pathology, Department of
Publisher: England
Identifiers: 99900546976901842
Language: English
Resource Type: Journal article