Figure 3.

Functional complementation of the yeast mutant defective for ammonium uptake. Growth of the ammonium transporter-deficient yeast strain triple mepΔ (31019b) expressing AtAMT1;1 (positive control), the empty pDR196 vector (negative control), or ScAMT2;1 on media supplied with 0.5 to 5 mM ammonium chloride (NH₄ ⁺), 100 mM methylammonium (MeA), or 1 mM arginine (Arg; positive control) as the sole N source. Culture media pH was adjusted to 6.0 when not indicated otherwise. Each transformant line was grown to OD_600nm = 1 and plated in concentrated and sequential four 10-fold dilutions.