Spatial pattern of genetic diversity in field populations of Fusarium incarnatum-equiseti species complex

Fusarium is associated with a number of wilt, blight, scab and rot
diseases in a range of economically important staple food crops worldwide.
An assessment of the genetic structure and population stratification of
Fusarium incarnatum-equiseti species complex (FIESC) pathogen populations
is important to understand the evolutionary potential of such populations
in adapting to environmental change. Based on inter-simple sequence repeat
polymerase chain reaction (ISSR-PCR), it was found that the pathogen
population was structured into three genetic clusters for which genetic
differentiation was higher within than among populations. There was high
intra-population genetic diversity for population 1 (94.63%) which
consisted largely of isolates collected from North Trinidad. Populations 2
and 3 had a low level of admixture among the populations based on overall
population differentiation. Population 1 accounted for the highest amount
of genetic variation (95.82%) followed by populations 2 and 3. Population
stratification was reflected in the dendrogram topology, which consisted
of three main genetic clusters and which coincided with the outcome of
Bayesian and PCoA analyses. The populations were isolated by distance and
Voronoi tessellations indicated physical or structural barriers to gene
flow which contributed to restricted admixture between two of three
populations. These findings suggest a high evolutionary potential for this
FIESC pathogen population, the implications of which directly affect
disease management strategies.