Physiological Changes in During the C to CAM Transition Induced by Salt Stress.

Salt stress impedes plant growth and development, and leads to yield loss. Recently, a halophyte species has become a model to study plant photosynthetic responses to salt stress. It has an adaptive mechanism of shifting from C photosynthesis to crassulacean acid metabolism (CAM) photosynthesis under stresses, which greatly enhances water usage efficiency and stress tolerance. In this study, we focused on investigating the morphological and physiological changes [e.g., leaf area, stomatal movement behavior, gas exchange, leaf succulence, and relative water content (RWC)] of during the C to CAM photosynthetic transition under salt stress. Our results showed that in seedlings, CAM photosynthesis was initiated after 6 days of salt treatment, the transition takes place within a 3-day period, and plants became mostly CAM in 2 weeks. This result defined the transition period of a facultative CAM plant, laid a foundation for future studies on identifying the molecular switches responsible for the transition from C to CAM, and contributed to the ultimate goal of engineering CAM characteristics into C crops.