Figure 4.

Northern analyses of wheat chloroplastic Cu/ZnSOD (a) and mitochondrial MnSOD (b) genes during cold stress under natural conditions. Total RNA extracted from spring wheat cv Katepwa and winter wheat cv Norstar seedlings harvested on September 26 (S26), September 30 (S30), October 9 (O9), October 15 (O15), and October 22 (O22) or freeze-thaw plants harvested on October 22 (FT) was separated by 1.2% agarose-gel electrophoresis and transferred to a nylon membrane. The same blot was sequentially hybridized with Cu/ZnSOD 1.1 and MnSOD 3.1 and washed under high-stringency conditions. EtBr (c) and LT₅₀ (d) represent ethidium bromide-stained gels and temperatures (°C) that killed 50% of plants, respectively.