Figure 2.

Photosynthetic efficiency of leaves from control and transgenic alfalfa clone N4-4-2 expressing pExSOD10 following exposure to oxidative stress produced by methyl viologen. Photosynthetic efficiency was measured by chlorophyll fluorescence as the F_v/F_m ratio following treatment of leaves from control (●) and transgenic (▪) plants with various concentrations of methyl viologen. The experiment was repeated twice, with five replications per experiment. Values of the transgenic plants are the least squares means of three independent transgenic plants (designated as Fe-SOD-13, -25, and -30 from Table I) that were not significantly different according to analysis of variance. se = 0.037 (n = 10 control) and 0.021 (n = 30 transgenic).