GNPS - Integrated analysis of transcriptomics, metabolomics and proteomics approach to understand the importance of ABA-dependent pathways in facultative plant Mesembryanthemum Crystallinum leaf during the salt induced C 3 to CAM transition to explore the mechanism of this shift.

Mesembryanthemum crystallinum, a facultative CAM plant, shifts from C3 to CAM photosynthesis under salt stress, enhancing water use efficiency due to inverse stomatal patterns. Exploring the mechanisms of this transition could improve salt tolerance in C3 crops. We used transcriptomics, proteomics, and targeted metabolomics every 8 hours to track molecular shifts during this transition. Results confirmed changes in CAM photosynthesis, starch biosynthesis, degradation, and glycolysis/gluconeogenesis. Transcripts displayed greater circadian regulation than proteins. Oxidative phosphorylation was crucial, with the inositol pathway, involving methylation and phosphorylation, potentially initiating the transition. V-type ATPases showed consistent transcription regulation, aiding in vacuolar osmotic pressure maintenance. ABI1, a major component in the ABA signaling pathway, could be the trigger for the salt-induced transition, as it inhibits ABA-dependent stomatal closure. Our work highlights the pivotal role of ABA pathways in the C3 to CAM shift.