Author(s)

Yuya Higashi¹, Katsuaki Takechi¹, Hiroyoshi Takano¹, Susumu Takio^1,2

¹Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
²Center for Marine Environment Studies, Kumamoto University, Kumamoto, Japan.

Superoxide dismutases (SODs) catalyze the dismutation of superoxide and play an important role in reducing oxidative stress in plants. Based on in-gel SOD activity staining, chloroplasts of the moss Physcomitrella patens have two CuZn-SODs as the major SOD isozymes and minor SODs, including a Fe-SOD and two Mn-SODs. To investigate the contribution of chloroplastic SODs to stress tolerance in P. patens, we generated a double mutant lacking chloroplastic CuZn-SOD genes. The mutant did not show any differences in comparison to the wild type based on the growth of protonemata on normal and high-salt media, extractable activities of the other SODs after culture on normal and high-salt media, and inhibition of Fv/Fm under stress conditions (high-salt, high-light, and high-temperature). These results indicate that chloroplastic CuZn-SODs do not play a principal role in oxidative stress tolerance in chloroplasts under the investigated conditions. These findings explain the previously reported unusual response of P. patens to copper deficiency, in which chloroplastic CuZn-SODs are preferentially inactivated but cytosolic CuZn-SODs are unaffected.

Chloroplast, Knockout Mutant, Physcomitrella patens, Stress Tolerance, Superoxide Dismutase

Higashi, Y. , Takechi, K. , Takano, H. and Takio, S. (2015) Maintenance of Normal Stress Tolerance in the Moss Physcomitrella patens Lacking Chloroplastic CuZn-Superoxide Dismutase. American Journal of Plant Sciences, 6, 591-601. doi: 10.4236/ajps.2015.65064.