Potato tubers from S. tuberosum were harvested in the late summer and stored at 4°C in the dark
for 4 months. The potato plants were cultivated in a growth chamber at 25°C with fluorescent light (250 mmol/m2/s), under a 14 h photoperiod. Four to five week-old plants at the vegetative stage were analysed. For this purpose, stems, fully expanded leaves (mature leaves) and developing leaves (young leaves) were harvested, frozen in liquid nitrogen and stored at −80°C. Potato buds from previously induced sprouting tubers were also collected. F. eumartii was obtained from the INTA Collection, Balcarce, Argentina. The fungus was grown at 25°C on potato dextrose agar (PDA) in Petri dishes for 3 weeks with fluorescent light (150
mmol/m2/s) under a 14 h photoperiod.