Over-expression of PaSOD in transgenic potato enhances photosynthetic performance under drought

Drought stress enhances the production of superoxide radical (O-2(is approximately equal to)) and superoxide dismutase catalyses dismutation of it to H2O2 and O-2, and hence provides a first line of defense against oxidative stress. Over-expression of a cytosolic copper-zinc superoxide dismutase, cloned from Potentilla atrosanguinea (PaSOD), in potato (Solanum tuberosum ssp. tuberosum L. cv. Kufri Sutlej) resulted in enhanced net photosynthetic rates (P-N) and stomatal conductance (g(s)) compared to that in the wild type (WT) plants under control (irrigated) as well as drought stress conditions. Drought stress declined leaf water potential, P-N, g(s), photosystem II activity, and chlorophyll content, but increased proline and O-2(is approximately equal to) content more in WT than transgenic potato plants (SS5). The significantly higher SOD activity in SS5 coincided well with lower O-2(is approximately equal to) content suggesting its role in maintaining higher gs and PN in transgenic potato plants.