Regulation Of Drought-Related Responses In Tomato Plants By Two Classes Of Calcineurin B-Like (Slcbl1/2) Proteins

Calcineurin-B-like proteins (CBLs) are essential components of the calcium signaling network and act during plant's response to stress and normal conditions. A combined research strategy of in-silico analysis and gene silencing experiment was employed to investigate the role of different classes of CBLs in tomato (Solanum lycopersicum L.) during the response to drought stress. Two different classes of CBL genes, including SlCBL3-1, and SlCBL3-2, with the minimum and a maximum number of drought-responsive cis-elements, were selected and were targeted for transient gene silencing in tomato followed by the drought treatment. The effect of silencing events was evaluated by determining of further growth and physiological traits in plants under both control and drought stress conditions. The results showed that silencing of SlCBL3-1 significantly reduced shoot and root growth, relative water content (RWC), and the concentration of pigments while increased free radical accumulation, lipid peroxidation, and leakage from the cells. On the other hand, no antioxidant enzyme activity or proline induction was triggered in plants after SlCBL3-1 silencing. Some of these adverse events were more significantly enhanced when the silenced plants were exposed to drought stress. Overall, a significant role for SlCBL3-1 in the life cycle of plant suggested under both normal and stress conditions. The SlCBL3-2 silencing showed more efficient plants recovery from silencing or drought stress conditions. Therefore, SlCBL3-2 gene may act as a negative regulator under stress conditions. The results might provide new theoretical insight and genetic resources for developing resistant crops against environmental stresses.