Using genetic markers to investigate natural selection in fungal populations

Ennos, Richard A.; McConnell, Kristi

doi:10.1139/b95-260

Cited by 30 publications

(18 citation statements)

References 19 publications

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“…The genetic structure of C. geophilum might reflect its physiological diversity (Panaccione et al 2001;Jany et al 2002;Douhan and Rizzo 2005), with natural selection of genotypes adapted to particular soil conditions (Ennos and McConnell 1995). Previous studies using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis of rDNA loci and inter-simple sequence repeats (ISSR) revealed high genetic variability in C. geophilum isolates from serpentine and non-serpentine sites in Portugal, especially among isolates of different morphological types (Portugal et al 2001;Portugal et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Genetic diversity and differential in vitro responses to Ni in Cenococcum geophilum isolates from serpentine soils in Portugal

et al. 2007

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Amplified fragment length polymorphism (AFLP) analysis was used to investigate the genetic diversity in isolates of the ectomycorrhizal fungus Cenococcum geophilum from serpentine and non-serpentine soils in Portugal. A high degree of genetic diversity was found among C. geophilum isolates; AFLP fingerprints showed that all the isolates were genetically distinct. We also assessed the in vitro Ni sensitivity in three serpentine isolates and one non-serpentine isolate. Only the nonserpentine isolate was significantly affected by the addition of Ni to the growth medium. At 30 μg g −1 Ni, radial growth rate and biomass accumulation decreased to 73.3 and 71.6% of control, respectively, a highly significant inhibitory effect. Nickel at this concentration had no significant inhibitory effect on serpentine isolates, and so the fitness of serpentine isolates, as evaluated by radial growth rate and biomass yield, is likely unaffected by Ni in the field. In all isolates, the Ni concentration in the mycelia increased with increasing Ni concentration in the growth medium, but two profiles of Ni accumulation were identified. One serpentine isolate showed a linear trend of Ni accumulation. At the highest Ni exposure, the concentration of Ni in the mycelium of this isolate was in the hyperaccumulation range for Ni as defined for higher plants. In the remaining isolates, Ni accumulation was less pronounced and seems to approach a plateau at 30 μg g −1 Ni. Because two profiles of Ni accumulation emerged among our Ni-insensitive serpentine isolates, this result suggests that different Ni detoxification pathways may be operating. The nonserpentine isolate whose growth was significantly affected by Ni was separated from the other isolates in the genetic analysis, suggesting a genetic basis for the Ni-sensitivity trait. This hypothesis is further supported by the fact that all isolates were maintained on medium without added Ni to avoid carry-over effects. However, because AFLP analysis failed to distinguish between serpentine and non-serpentine isolates, we cannot conclude that Ni insensitivity among our serpentine isolates is due to evolutionary adaptation. Screening a larger number of isolates, from different geographical origins and environments, should clarify the relationships between genetic diversity, morphology, and physiology in this important species.

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Section: Introductionmentioning

confidence: 99%

Genetic diversity and differential in vitro responses to Ni in Cenococcum geophilum isolates from serpentine soils in Portugal

et al. 2007

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“…where q 0 and q 1 are the frequencies, at censuses 0 and 1, respectively, of the inoculum component that decreases in frequency, and p 0 and p 1 are the frequencies, at censuses 0 and 1, respectively, of the inoculum component that increases in frequency (Ennos and McConnell, 1995).…”

Section: Assessment Of Infectionmentioning

confidence: 99%

“…This can be investigated by measuring the relative success of genetically marked pathogens when grown in mixture on a variety of host populations, individuals and tissues. Comparisons of pathogen genotype performance in these situations can be used to estimate their relative selective values using a range of established techniques (Ennos and McConnell, 1995).…”

Section: Introductionmentioning

confidence: 99%

Variation in host resistance and pathogen selective value in the interaction between Pinus sylvestris and the fungus Crumenulopsis sororia

Ennos

McConnell

2003

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There have been many studies of plant pathogen evolution in systems showing gene-for-gene control of host resistance. However little is known about situations, exemplified by Scots pine, Pinus sylvestris, and its fungal pathogen Crumenulopsis sororia, where variation in host resistance is quantitative. In a field experiment genetically marked isolates of C. sororia from three natural populations were reciprocally inoculated on 1-and 2-year-old branch tissue of P. sylvestris in the three sites from which they had been collected. Quantitative variation in host resistance was measured by comparing the performance of the same inocula on different host populations, individuals and tissues. The selective value of isolates derived from different populations was estimated by comparing the frequency of genotypes in lesion re-isolations with those in the initial inoculum mixtures. Host resistance varied significantly among populations, individuals within populations and between 1-and 2-year-old branch tissue of P. sylvestris. Large differences in the relative selective values of C. sororia isolates from different populations were detected. The selective value of pathogens was independent of the host population on which they were inoculated. However, their selective value did depend on the age of the tissue on which they grew. The implications of these results for modelling evolution in pathogen-host interactions that lack gene-forgene determination of host resistance are discussed.

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“…Future efforts will certainly continue. to expand our knowledge of the population biology of this group and may provide an opportunity to directly assess how natural selection operates in fungal populations (Ennos and McConnell, 1995).…”

Section: Conclusion/summarymentioning

confidence: 99%