Changes in specific virulence in Polish populations ofPhytophthora infestans: 1985–1991

Abstract

Ninety-five isolates ofPhytophthora infestans collected throughout Poland during 1985-1991 and characterized for multilocus genotypes based on mating type, allozymes and DNA fingerprint, were analyzed for specific virulence to differential potato cultivars carrying ten major resistance genes. The multilocus analysis led to three groupings. The first group contained 22 isolates of a clonal lineage (PO-1) that is postulated to have been present in Europe during most of the twentieth century, but PO-1 isolates were recovered in Poland only during 1985-1988. This group contained, on average, virulence to 5.5 specific resistance genes per isolate. The second group consisted of 30 isolates in a clonal lineage (PO-4) that had not been detected before 1988. PO-4 isolates had virulence to a mean of 6.5 resistance genes per isolate. The third group was composed of 43 isolates representing 38 multilocus genotypes also not detected before 1988. These diverse genotypes had virulence to an average of 6.7 specific resistance genes per isolate. More than half (53%) of the PO-4 isolates shared a single pathotype. The group of 43 isolates was dominated by two pathotypes: the most common one (47% of the isolates) was the same pathotype that dominated PO-4 isolates; the next most common one (21%) differed from the most common one by the absence of virulence to resistance gene R5. The recent immigrant isolates (not detected before 1988) generally had virulence to a greater number of specific resistance genes than did isolates in the previous population [detected before 1988 (PO-1)]. Recent immigrant populations were dominated by one or two pathotypes, so their pathotypic diversity values were somewhat less than that of the previous population.

Effects of cropping history and origin of seed potatoes on population structure of Phytophthora infestans

“…Generally, the similarity of our isolates with the US lineages was low as in the study of Knapova and Gisi (2002) comparing French and Swiss isolates with isolates of the US lineages, supporting the hypothesis of Goodwin, Cohen, Deahl, and Fry (1994) that the European populations may have evolved independently from the populations in the US. This is supported by results of characterization studies on composition and diversity of P. infestans populations in different European countries (Day, Wattier, Shaw, & Shattock, 2004;Drenth et al, 1994;Fry, Drenth, Mantel, Davidse, & Goodwin, 1991;Sujkowski, Goodwin, & Fry, 1996). The overall diversity among the 281 isolates that were analyzed with rep-PCR and two primers (H¢ = .64) was similar to a Canadian study employing RAPD analysis.…”

Important Threats in Potato Production and Integrated Pathogen/Pest Management

“…Late blight is a very common disease that causes losses of up to 70% in uncontrolled fields (Hoffman and Schmutterer 1983), and at early infections 100% loss of tuber yields (Fry 1994). An increase in infection potential of P. infestans caused by genetic changes in pathogen population and higher infection pressure was observed all over the world over the last two to three decades (Spielman et al 1991;Fry et al 1993;Andrivon 1994;Drenth 1994;Duvauchell and Lherbier 1996;Sujkowski et al 1996;Turkensteen et al 1996;Hermansen et al 2000). The occurrence of new populations of P. infestans becomes evident during the development of late blight.…”

The structure of Phytophthora infestans populations from organic and conventional crops

“…The new population also contains both Ia and IIa mtDNA haplotypes (Day and Shattock 1997;Lebreton and Andrivon 1998). In many cases, there has been an increase in the complexity of virulence phenotypes (Sujkowski et al 1996;Hermansen et al 2000;Lehtinen et al 2008).…”