Evaluation of two native succulent species that can switch from C3 to CAM in salty and dry soils of Lake Urmia

Due to the drying trend of Urmia Lake, climate change and frequent occurrence of droughts in the region, verification of photosynthetic flexibility in the floral elements of Lake Urmia is important. In this work, the ability of Rosularia elymaitica and Zygophyllum fabago species to shift from C3 to Crassulacean acid metabolism (CAM) as well as survival and productivity of these plants were studied in both salty and dry soils of Lake Urmia. While salinity alone was not able to induce functional CAM expression in both species, we showed that drought alone induced low level of nocturnal acid accumulation in both species, which were similar to acid fluctuations in CAM-cycling pathway, as an initial stage of CAM. We indicated that Z. fabago species have a high tolerance to combined drought (30 days water dificit) and salt (7±0.42 dSm-1) stresses in salty and dry soils of the Lake Urmia, as compared to R. elymaitica plants. This higher tolerance was correlated with up-regulation of phosphoenolpyruvate-carboxylase (PEPC) activity and maintenance of higher photochemical functioning. As a result, this research introduces Z. fabago as an important climate-resilient crop, which can switch from C3 to CAM in salty and dry soils of the Lake Urmia.