Overexpression of a Calvin cycle enzyme SBPase improves tolerance to chilling-induced oxidative stress in tomato plants

Abstract Sedoheptulose-1,7-bisphosphatase (SBPase) is a critical enzyme involved in photosynthetic carbon fixation in the Calvin cycle. Here, we report the effects of SBPase overexpression on the tolerance to chilling-induced oxidative stress in transgenic tomato ( Solanum lycopersicum ) plants. In transgenic plants overexpressing SBPase, CO 2 fixation and carbohydrate accumulation were increased in comparison with equivalent wild-type plants. SBPase was found to be susceptible to oxidative stress and the activity was substantially inhibited by reactive oxygen species both in vivo and in vitro . In response to chilling stress, production of H 2 O 2 was increased in parallel with the reduction in SBPase activity in tomato plants, however, transgenic plants maintained significantly higher SBPase activity than wild-type plants did. Under chilling stress, compared with wild-type plants, transgenic plants were found to have increased CO 2 fixation and reduced electrolyte leakage. The overall tolerance could be ascribed to the enhancement of photosynthetic carbon fixation, the reductions in the level of H 2 O 2 and the increased accumulation of carbohydrate in transgenic plants. Collectively, our data suggest that high level of SBPase activity gives an advantage to photosynthetic carbon fixation and tolerance to chilling-induced oxidative stress in tomato plants. This work presents a case study that an individual enzyme in the Calvin cycle may be a useful target for genetically engineering stress tolerance in horticultural crops.