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Genetic diversity and population structure of the potential biocontrol agent, Valdensinia heterodoxa, and its host Gaultheria shallon (salal) Wilkin, Jennifer
Abstract
Valdensinia heterodoxa Peyronel is an ascomycete fungus currently being considered as a potential biocontrol agent for Gaultheria shallon Pursh. (salal). In order to design an effective biocontrol agent and to assess its effectiveness and risks, the population structure of both V. heterodoxa and salal must be investigated. Infected salal leaves were collected from three geographically separate populations on Vancouver Island and coastal mainland British Columbia. Uninfected salal was collected from two additional sites. V. heterodoxa was cultured from the infected leaves and single spore cultures were obtained prior to DNA isolation. Amplified fragment length polymorphisms (AFLPs) were used to generate individual DNA fingerprints for each isolate. Of the 214 loci analyzed, 30 % were polymorphic, suggesting low genetic diversity. There were many shared haplotypes within each population, and as expected, analysis of pairwise kinship coefficients showed that as spatial distance increased, genetic similarity decreased. Analysis of molecular variance (AMOVA) between populations revealed significant genetic differentiation between populations with an FST of 0.18, perhaps a result of limited gene flow. Salal DNA was isolated from leaf tissue and AFLPs were used to fingerprint individuals resulting in 230 loci, which were 89.7% polymorphic on average. Within population diversity was high, with an average observed heterozygosity of 0.49. In addition, due to the high ploidy level of salal (octoploid), the results obtained from the dominant AFLP markers likely underestimate the actual genetic diversity in the populations. Populations were poorly differentiated (FST 0.096 ) , suggesting high gene flow among populations. Within one population (Shawnigan Lake), genetic similarity decreased with increased geographic distance and showed little evidence of clonal population structure. ii When the genetic variation in V. heterodoxa was compared to that in salal, high correlations of alleles observed between the species suggest that different V. heterodoxa pathogenicity groups, or salal varieties with varying levels of susceptibility, could be contributing to the distribution of V. heterodoxa in these populations. Overall, the findings from the genetic analyses were used to discuss the potential risks of using V. heterodoxa as a biocontrol agent for salal and suggest that with low diversity and high population differentiation, the effectiveness of V. heterodoxa as a biocontrol may be limited to use within local salal populations or in combination with other control methods to effectively manage salal in forested areas.
Item Metadata
Title |
Genetic diversity and population structure of the potential biocontrol agent, Valdensinia heterodoxa, and its host Gaultheria shallon (salal)
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2004
|
Description |
Valdensinia heterodoxa Peyronel is an ascomycete fungus currently being
considered as a potential biocontrol agent for Gaultheria shallon Pursh. (salal). In order
to design an effective biocontrol agent and to assess its effectiveness and risks, the
population structure of both V. heterodoxa and salal must be investigated. Infected
salal leaves were collected from three geographically separate populations on
Vancouver Island and coastal mainland British Columbia. Uninfected salal was
collected from two additional sites. V. heterodoxa was cultured from the infected leaves
and single spore cultures were obtained prior to DNA isolation. Amplified fragment
length polymorphisms (AFLPs) were used to generate individual DNA fingerprints for
each isolate. Of the 214 loci analyzed, 30 % were polymorphic, suggesting low genetic
diversity. There were many shared haplotypes within each population, and as
expected, analysis of pairwise kinship coefficients showed that as spatial distance
increased, genetic similarity decreased. Analysis of molecular variance (AMOVA)
between populations revealed significant genetic differentiation between populations
with an FST of 0.18, perhaps a result of limited gene flow.
Salal DNA was isolated from leaf tissue and AFLPs were used to fingerprint
individuals resulting in 230 loci, which were 89.7% polymorphic on average. Within
population diversity was high, with an average observed heterozygosity of 0.49. In
addition, due to the high ploidy level of salal (octoploid), the results obtained from the
dominant AFLP markers likely underestimate the actual genetic diversity in the
populations. Populations were poorly differentiated (FST 0.096 ) , suggesting high gene
flow among populations. Within one population (Shawnigan Lake), genetic similarity
decreased with increased geographic distance and showed little evidence of clonal
population structure.
ii When the genetic variation in V. heterodoxa was compared to that in salal, high
correlations of alleles observed between the species suggest that different V.
heterodoxa pathogenicity groups, or salal varieties with varying levels of susceptibility,
could be contributing to the distribution of V. heterodoxa in these populations. Overall,
the findings from the genetic analyses were used to discuss the potential risks of using
V. heterodoxa as a biocontrol agent for salal and suggest that with low diversity and
high population differentiation, the effectiveness of V. heterodoxa as a biocontrol may
be limited to use within local salal populations or in combination with other control
methods to effectively manage salal in forested areas.
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Extent |
9562918 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-11-17
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0075050
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2004-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.