Differential expression of sod genes in V. volvacea H1521 stressed at low temperature for different times. Control (−), hyphae were incubated in phosphate buffered solution (PBS) buffer (0.02 mol/L, pH 8, 34 °C) for 1.5 h at 34 °C. Cold stress treated (+), hyphae were incubated in PBS buffer (0.02 mol/L, pH 8, 34 °C) for 0.5 h at 34 °C and then in PBS buffer (0.02 mol/L, pH 8, 4 °C) at 4 °C for 1 h. Data are the averages of four independent experiments. The error bars show the standard error of the mean. Statistical analysis was performed using least significant difference (LSD) test, ** p < 0.01.