Figure 5.

Overexpression of OsCYP21-4 increases salt stress tolerance in rice. (A,D) Comparison of rice seedlings under NaCl stress. Transgenic plants (OE) and wild-type (WT) seeds were germinated on MS medium with or without hygromycin (50 mg/L), respectively, and after 3 days, they were transferred to fresh MS medium plates (A) or to distilled water containing 0, 150 or 200 mM NaCl (D) and grown for 5 days. (B,C) Relative root length and fresh weight of transgenic and WT control seedlings grown on MS medium plates. Error bars mean SE of three biological replicates. Asterisks indicate statistically significant differences between WT control and OsCYP21-4 OE transgenic plants (Student's t-test: ^*p < 0.1, ^**p < 0.01). (E) In situ H₂O₂ accumulation in plants shown in (D) was detected by 3,3′-diaminobenzidine (DAB) staining. The experiments were repeated twice with similar results obtained in each experiment. (F,G) Relative peroxidase and ascorbate peroxidase activities in WT and OsCYP21-4 OE plants. Error bars denote SE of three biological replicates. Asterisks indicate statistically significant difference between WT control and OsCYP21-4 OE transgenic plants (Student's t-test: ^*p < 0.1, ^**p < 0.05). Bars = 2 cm (A,D) and 2 mm (E).