Portulaca oleracea is one of the uncommon cases in which a plant is able to cycle between two CO2 concentrating mechanisms (i.e., C4 and CAM), thereby contradicting the theory that C4 and CAM are incompatible and highlighting how our knowledge about these photosynthetic adaptations is still limited. Whether plant hormones play a significant role in regulating C4 and CAM when these syndromes occur in the same organism also remains to be investigated. Based on this scenario, this work aims to characterize the hormonal signaling potentially involved in controlling the C4-CAM transitions in P. oleracea. First, we will use the transcriptome data for this species, which was recently generated by our research group, in order to select hormone metabolism-, transport- and signaling-related genes potentially regulating the C4 and CAM expression in this species. Leaves from plants submitted to three distinct watering regimes (i.e., well-watered, droughted, and droughted followed by rewatering) will be sampled during the photosynthetic transitions (C4-to-CAM and CAM-to-C4), and the transcripts relative abundance of target genes will be analyzed via quantitative PCR (RT-qPCR). CAM expression will also be monitored via both biochemical and gene expression analysis. Altogether, these analyses have the potential to uncover the hormonal regulatory mechanisms facilitating the rare occurrence of both CAM and C4 photosynthesis in a single individual, which can be useful for future bioengineering projects aiming to incorporate CAM into C4 plants.
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