Expression levels of reference gene candidates during different cultural conditions. Gene expression levels (represented by absolute Ct values) of (A) rplI, rplQ, tsx and malE in MMcap, MMg and LB, (B) glnA, rho and topA in MMcap, MMg, LB, LBexp, LBst and MMcip and (C) ffh, gyrA, proC, recA and 16S in MMcap, MMg, LB, LBexp, LBst, MMcip and infiltrated leaflets. For explanations of abbreviations, see Table 3. Each bar represents the mean of three samples from independent RNA isolations from three cultures, except for the leaves bar, which come from two independent RNA isolations from a pool of three vacuum infiltrated leaflets. Error bars indicate standard deviations.