p5cdh-2 mutants are more sensitive to external Pro supply than pdh1 mutants. A: Col-8 and Ler wildtypes, pdh1-1, pdh1-4, pdh2-1 and p5cdh-2 seedlings were cultivated for 2 weeks on MS medium with 5 mM Pro as the sole source of nitrogen and 15 mM sucrose as carbon source, buffered to pH 5.8 with 5 mM MES. B: Hypocotyl elongation of Col-8 wildtype, pdh1-1, pdh1-4 and p5cdh-2 seedlings cultivated on MS medium supplemented with 30 mM sucrose and varying concentrations of Pro. Error bars indicate SD of ≥ 10 seedlings per genotype. The experiments were repeated with similar results.