Transcriptional and protein activity characterization of the SA transgenic plants. (a) qRT-PCR analysis of MeCu/ZnSOD and MeAPX2 expression levels both in WT and SA transgenic cassava lines. Total RNA was extracted from leaves of in vitro plants and the data are shown relative to the WT, using β-actin as an internal control. Data are presented as mean ± SD of three independent RNA samples. (b) SOD and APX isoforms in greenhouse-grown leaves of WT and transgenic plants detected by staining of non-denaturing polyacrylamide gel. Three SOD isoforms, MnSOD, FeSOD and Cu/ZnSOD, are indicated. The Rubisco LSU protein was used as a loading control. WT, wild-type control; SA with numbers, independent transgenic plant lines.