Changes of Genotype, Sensitivity and Aggressiveness in Phytophthora infestans Isolates Collected in European Countries in 1997, 2006 and 2007

Abstract

A total of 241 isolates of Phytophthora infestans were collected in 1997, 2006 and 2007 in eight European countries and characterized with molecular markers (simple sequence repeats, SSR genotypes) and phenotypic traits such as sensitivity to fungicides, mating type and aggressiveness. The mating type distribution changed from mainly A1 in 1997 to a majority of A2 in 2007. No resistant isolates were detected for fluazinam and mandipropamid, whereas the proportion of isolates resistant to mefenoxam (MFX) was high and increased over the years. There was no genetic link between mating type and MFX resistance. Aggressiveness (product between lesion expansion and sporulation capacity) was slightly higher for MFX-resistant compared to sensitive isolates and for isolates collected later compared to earlier in the same season. It was about equally high for A1 and A2 types, and for French isolates in 1997 and British isolates in 2007, but lower for French isolates in 2007. Six different SSR genotype families were distinguished. In 1997, populations were dominated by genotype families I and III⁄IV, which significantly declined in 2007 being largely displaced by genotype families II (Ôblue 13Õ type) and V, which are by coincidence mainly A2 MFX resistant and A1 MFX sensitive, respectively. However, mating type and MFX resistance were genetically not linked to SSR genotypes.

Characterization ofPhytophthora infestanspopulations in Canada during 2012

“…In recent years, disease severity and pathogen diversity rapidly increased with the occurrence of new genotypes in North America and elsewhere (Gisi et al 2011;Hu et al 2012;Kalischuk et al 2012;Chowdappa et al 2013;Fry et al 2013;Peters et al 2014). Such rapid changes in P. infestans populations suggest that sexually reproducing populations of P. infestans may now be established in Canada.…”

Diversity of Phytophthora infestans from Poland

“…The highly aggressive genotype 13_A2 has been spreading in western Europe; it was first found in 2004 and in 2006–2007 it was dominating in the Netherlands, France, United Kingdom, Switzerland, Germany and Belgium, although not in Denmark (Gisi et al ., ). This genotype was also found in the present study, represented by eight isolates.…”

Phenotypic and genotypic changes in French populations of Phytophthora infestans: are invasive clones the most aggressive?

“…Throughout the 2001–2008 period, the genetic structure of French P. infestans populations was characterized by low to moderate levels of genetic diversity, a low level of recombination as suggested by the high index of association, and the dominance of a few clonal lineages. These observations confirm the prevalence of clonal reproduction in West European populations of this pathogen, with little or no evidence of recombination (Montarry et al ., ; Gisi et al ., ; Cooke et al ., ; Glais et al ., ).…”