Drought priming at vegetative stage improves the antioxidant capacity and photosynthesis performance of wheat exposed to a short-term low temperature stress at jointing stage

To study the effects of multi-occurring stresses and the underlying mechanisms of cross-stress tolerance. Wheat plants were exposed to moderate drought priming (the leaf water potential reached ca. -0.8 MPa) at the 5-6th leaf stage for 2 weeks, and the physiological and yield responses of the drought-primed and non-primed plants to low temperature stress (4/ 2 A degrees C in the day/ night for 2 days) at jointing stage were investigated. Under low temperature stress, the primed plants possessed higher leaf relative water content and much activated antioxidant system and hence reduced the oxidative injury to the photosynthetic apparatus, resulting in greater photosynthetic rate and higher grain yield as compared with the non-primed plants. In addition, increase of the ABA concentrations in leaf was found closely associated with the enhanced anti-oxidant enzymes activity in the primed plants. Drought priming at vegetative stage improves cold tolerance of wheat at jointing stage via sustaining ROS homeostasis, during which ABA plays a key role in alleviating the effects of low temperature stress in the drought-primed plants.