Enhanced tolerance to H
-mediated oxidative stress in SA transgenic leaves. (a) H2O2 accumulation in leaves detected by 3,3′-diaminobenzidine (DAB) staining. Scale bar = 0.5 cm. (b) Changes in levels of H2O2 concentration between WT and transgenic cassava during 0.5 M H2O2 treatment. (c) and (d) Changes in SOD and APX activities between WT and transgenic cassava during H2O2 treatment. WT, wild-type control; SA1, SA2 and SA4, independent transgenic plant lines. Values represent the means of three independent experiments ± SD. **Significant at 1% level from WT by t-test.