Pathogen elicitorThe pathogen P. infestans (isolate MP618 from 2005, of followingrace: 1.2.3.4.(5).6.7.10.11, A1 mating type and resistant to metal-axyl) received from IHAR-PIB, Młochów Research Center, Poland,was maintained on rye agar medium at 15◦C in the dark. A cul-ture filtrate (CF), which served as an elicitor, was prepared fromthe pathogen grown in liquid medium. After 6 weeks of growth,the medium was separated from the oomycete, dialyzed againstwater for 48 h, and lyophilized. The CF residue dissolved in distilledwater was quantified as g glucose equivalents mL−1, as describedin detail by Polkowska-Kowalczyk et al. (2004).