To analyse the variation between isolates, results for the different clonal lines were combined with no significant difference observed between the three isolates of Phytophthora pluvialis that were applied (Figure 9).
Chromosome alignments indicated significant conservation of genome architecture between the three isolates.
More generally, with the exception of the Type 3 var genes and var1csa, the UpsA-associated var genes are not highly conserved between the three isolates.
We used neutral microsatellite markers to study the genetic relationship between the three isolates and an additional set of 18 P. viticola isolates collected in different European countries (mainly France, Italy, Czech Republic).
Although the general chromosomal distribution of var genes in sub-telomeric regions or central regions on chromosomes 4, 6, 7, 8, and 12 are similar between the three isolates, the genes themselves are not conserved with the exception of var1csa, var2csa and Type 3 var.
No significant differences were observed between the three isolates based on the t-test (for the treatment with 5 × 10 CFU mL−1, BMG 93 versus BMG 184, P = 0.29; BMG 93 versus BMG 259, P = 0.56; BMG 184 versus BMG 259, P = 0.54; for the treatment with 10 CFU mL−1, BMG 93 versus BMG 184, P = 0.053; BMG 93 versus BMG 259, P = 0.09; BMG 184 versus BMG 259, P = 0.18).
Altogether these analyses revealed a strong overlap between the impacts of all the three isolates.
Intriguingly, we discovered statistically significant and divergent levels of gene expression between the two isolates profiled for 64 genes.
Where this was so in the third, haploid × haploid test, a small mycelium piece from the junction region between the two isolates was sub-cultured on 2 % malt agar to help clarify the result from its appearance.
