Figure 3.

Salt and oxidative stress sensitivity of ppr40-1 mutant. A, Seven-day-old ppr40-1 and wild-type (Col-0) seedlings on media supplemented with 200 mm NaCl. B, Germination frequencies of ppr40-1 (ppr) and wild-type (Col) seeds in the presence of 200 mm NaCl. ctr, One-half MS control medium; Na, 200 mm NaCl. C, Root growth of ppr40-1 and wild-type (Col-0) plants on vertical agar plates supplemented with different concentrations of NaCl. Root growth rate of 50 plants was calculated from data collected every day throughout an observation period of 10 d. D to F, Enhanced oxidative damage in the ppr40-1 mutant. Two-week-old wild-type (Col-0) and ppr40-1 plants were treated with 10 mm H₂O₂ and 2 μm paraquat for 4 d (D). Compared to wild type (Col-0), leaves of the ppr40-1 mutant show enhanced chlorosis. Diagrams (E and F) show reduction of chlorophyll levels in response to H₂O₂ and paraquat treatment throughout a period of 4 d, respectively. Different letters indicate significant differences at P < 0.05. G, Detection of hydrogen peroxide in leaves of wild-type (Col-0) and ppr40-1 plants by DAB histochemical assay.