Low genetic diversity and strong geographic structure in introduced populations of the Eucalyptus foliar pathogen Teratosphaeria destructans
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Date
Authors
Havenga, Minette
Wingfield, Brenda D.
Wingfield, Michael J.
Dreyer, Leanne Laurette
Roets, Francois
Chen, ShuaiFei
Aylward, Janneke
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
The aggressive Eucalyptus leaf pathogen, Teratosphaeria destructans, causes widespread damage in tropical and subtropical Eucalyptus‐growing regions of Indonesia, China, Thailand, East Timor, Vietnam, Lao, and South Africa. Little is known regarding the origin, pathways of dispersal, or reproductive biology of this pathogen. The aim of this study was to investigate the genetic structure of a global collection of T. destructans isolates. This was achieved by developing and using polymorphic microsatellite markers. Low genotypic diversity and a limited number of private alleles were found in all investigated populations, with the highest maximum diversity of 10.7% in isolates from South Sumatra. This supports the hypothesis that T. destructans was introduced to these regions. High levels of clonality were common in all populations, especially in isolates sampled from the recent disease outbreak in South Africa, which were all identical. The global collection of isolates grouped into three distinct clusters, corresponding largely to their sampled regions. Low levels of genotypic diversity, high levels of clonality, and strong geographic structure suggest independent introductions into all the sampled areas from an unknown source. The results imply that strict biosecurity measures are needed to avoid introductions of additional genotypes in these areas.
Description
Supporting Information:
Figure S1. Genotype accumulation curve for Teratosphaeria destructans. Nine loci were sufficient to identify 100% (red dashed line) of the multilocus genotypes (MLGs) present in the clone-corrected data set.
Figure S2. Rarefaction curve to calculate the expected multilocus genotypes (eMLG) in five Teratosphaeria destructans populations, indicative of genotypic richness.
Figure S3. Structure plot for Teratosphaeria destructans isolates from six geographic populations. The optimal number of genetic clusters (ΔK) = 3. Each vertical bar represents one individual.
Table S1. Sampling information and the MAT1 idiomorph, multilocus genotype (MLG), and discriminant analysis of principal components (DAPC) cluster identity for 195 Teratosphaeria destructans isolates.
Table S2. Probability of the occurrence and repeated occurrence of multilocus genotypes (MLGs) in the Teratosphaeria destructans data set, calculated in MLGsim v. 2.0.
Figure S2. Rarefaction curve to calculate the expected multilocus genotypes (eMLG) in five Teratosphaeria destructans populations, indicative of genotypic richness.
Figure S3. Structure plot for Teratosphaeria destructans isolates from six geographic populations. The optimal number of genetic clusters (ΔK) = 3. Each vertical bar represents one individual.
Table S1. Sampling information and the MAT1 idiomorph, multilocus genotype (MLG), and discriminant analysis of principal components (DAPC) cluster identity for 195 Teratosphaeria destructans isolates.
Table S2. Probability of the occurrence and repeated occurrence of multilocus genotypes (MLGs) in the Teratosphaeria destructans data set, calculated in MLGsim v. 2.0.
Keywords
Asexual reproduction, Foliar pathogen, Microsatellite markers, Population genetics
Sustainable Development Goals
Citation
Havenga M, Wingfield BD, Wingfield MJ, et al. Low genetic diversity and strong geographic structure in introduced populations of the Eucalyptus foliar
pathogen Teratosphaeria destructans. Plant Pathology 2020;69(8):1540-1550. https://doi.org/10.1111/ppa.13235.