Xr. Wang et al., GENETIC-VARIABILITY IN THE CANKER-PATHOGEN FUNGUS, GREMMENIELLA-ABIETINA .2. FINE-SCALE INVESTIGATION OF THE POPULATION GENETIC-STRUCTURE, Canadian journal of botany, 75(9), 1997, pp. 1460-1469
Genetic variation at 32 polymorphic random amplified polymorphic DNA l
oci was analysed in the ascomycete canker pathogen fungus Gremmeniella
abietina (Lagerb.) Morelet collected from one plantation of Pinus con
torta Dougl, ex Loud. in northern Sweden. The genetic variability main
tained in the G. abietina population was high. Many different multiloc
us genotypes were found on each tree and in each sampling site within
the plantation. The clonal fraction of the population was small, and i
dentical genotypes were found either on the same tree or branch or on
trees in the same sampling site. The finding of very few widely distri
buted clones suggests that the effective dispersal of asexual spores i
s limited to a few metres and resulted in small clusters of clones in
local sites. Analysis of molecular variance revealed that 45.3% of the
total variation was attributable to differences among isolates within
trees, 22.5% to trees within sites and 32.3% to sampling sites differ
ences. Allele frequencies at most of the loci varied significantly amo
ng the sampling sites and average total genetic diversity over the 32
loci was 0.27 indicating high population subdivision. The factors that
could have contributed to the observed population structure were disc
ussed.