Figure 2.

Toxicity of aromatic acids (•, Phe; ▾, Tyr; ▪, Trp) to wild-type Arabidopsis (cv Ws-2) in percent (A), dose-response curves for wild type (•) and pig1-1 (▾) after 14 d on different Tyr (B) and Trp (C) concentrations, and comparison of pig1-1 and Ws-2 after 14 d of growth on half-strength MS, 10 mm Phe, and 0.5% Suc (D). Per individual treatment, 100 to 200 seeds of the wild-type Ws-2 and pig1-1 were germinated on half-strength MS, 0.5% Suc supplemented with each of the given amino acid concentrations, and the survival rate was scored after 14 d of culture at 50 μmol m⁻² s⁻¹. A toxic effect was judged to be present when the plantlets died before the emergence of primary leaves or failed to germinate. The data were corrected for the germination rates on half-strength MS plates. Because of limiting Tyr solubility, the data point for 8 mm Tyr has been extrapolated according to the dose-response curves and the calculated I₅₀ (see “Results”) for Phe and Trp. Note that the toxicity of 10 mm Phe to pig1-1 was 18.8% ± 3.2% (data not shown).