Plant material - potato
Plant cultivation and stress treatments of two genotypes contrasting in their N deficiency response, namely ‘Lambada’ (sensitive) and ‘Topas’ (tolerant), were performed exactly as described (Jozefowicz et al., 2017). At the time of root appearance, after one week of cultivation, the nutrient solution was exchanged. Control plants were moved to fresh medium containing the original 20.6 mM NH4NO3 and 18.8 mM KNO3) and the plants for deficiency treatment were transferred to a medium with 1/16 of the N level. The loss of K (as a result of withholding KNO3) was compensated by the addition of KCl. After seven days, roots were harvested, snap-frozen in liquid N2 and stored at -80 °C. The experiment was performed in triplicate with six vessels per condition and cultivar.