The second most aggressive isolate

was an isolate designated as genotype US-22, Pi10-012, isolated from potato in 2010 from St. Joseph county, MI. The European lineages, designated as 13_A2 (also known as Blue-13), were also moderately aggressive on tuber tissue, with mean RARI values between 16.7 and 13.9. Along with Blue-13 genotypes, the isolate Pi09-011 (genotype US-22) obtained during the epidemics on 2009 from potato was moderately aggressive. The rest of the isolates used in this study caused less tissue darkening on the cultivars tested. The isolates Pi98-1 (US-14 genotype) and US-22F (US-22 genotype) had slightly lower aggressiveness in comparison with the more aggressive isolates. Michigan P. infestans isolates Pi10-023 and Pi09-021, characterized as genotype US-22 and isolated from tomato, were significantly different from the aggressive Metformin research buy isolate US-8 (Pi97-5) and grouped with isolates from Colombia, as low aggressive isolates on tuber tissue (Table 3). The two-way

interaction visualized as principal components analysis showed that for cultivars axis 1 and axis 2 accounted for 56.9 and 14.6% of the variability, buy Napabucasin respectively. With respect to the P. infestans, isolates axis 1 and axis 2 accounted for 36.4 and 13.1% of the variability, respectively (Fig. 2). Jacqueline Lee was the least variable of the cultivars due to its reduced susceptibility to most of the genotypes of P. infestans

evaluated. The other cultivars behaved in a similar fashion, Olopatadine where Dark Red Norland, Russet Burbank, FL1879 and Monticello were the most susceptible. Isolates of P. infestans were variable, but isolates assigned to genotype US-22 (Table 1) had reduced variability, which indicated that they had a diminished impact on tuber blight among the different cultivars evaluated (Fig. 2). Nonetheless, the isolates Pi09-011 and Pi10-012 identified as genotype US-22 obtained from potato were more aggressive on tuber tissue overall in comparison with other US-22 isolates. Also, the isolates Pi09-021 and Pi10-023 (US-22 genotype) from tomato were less aggressive than isolates US-8F and Pi97-5 (US-8 genotype) and 07-39 and 3298 (Blue-13). In general, Pi97-5 (US-8), 07-39 and 3298 (Blue-13) contributed most to variability among isolates and cultivars. The interactions between cultivars and isolates of the different genotypes of P. infestans are shown in Table 4. The isolate Pi97-5 (US-8) was highly aggressive in the different cultivars with mean RARI values ranging from 10 to 27%, and this isolate was chosen as an aggressive control in these studies. With respect to the US-22 isolates obtained in Michigan, Pi10-012 was moderately aggressive on most of the cultivars evaluated, with values 14.6 – 29.0%, but the isolates Pi09-021 and Pi10-023 isolated from tomato had consistently lower aggressiveness among cultivars (3.5–5.9 and 4–6.