Graduate Student University of Florida Gainesville, Florida
Body of Abstract: As the global population continues to grow, boosting food production while addressing climate change becomes crucial. However, rapidly diminishing water supplies and increasingly frequent droughts pose major challenges. To address this issue, we must find ways to improve plant resilience to drought. Most plants use the C3pathway for photosynthesis, but some have evolved the Crassulacean acid metabolism (CAM) pathway to adapt to arid conditions. A deeper understanding of CAM could allow transferring its water-conserving properties to drought-sensitive crops. However, lack of knowledge about key CAM regulators has hindered research in this area. Here, we present the single-cell transcriptome atlas of the common ice plant (Mesembryanthemum crystallinum) as a valuable resource for understanding the mechanisms of CAM induction. The ice plant is capable of completing its life cycle using only the C3 pathway, but can also reversibly induce CAM in response to high salinity or drought. To understand the major changes in gene expression that occur during CAM induction, transcriptomes from 22,656 nuclei at four different time points were analyzed. Differential expression of key CAM genes in different cell types after 8 days of salt treatment revealed that each cell type has a unique response to drought. Furthermore, mesophyll cells performing CAM cluster independently of those using the C3 pathway in the plants subjected to a salt stress. Subsequent trajectory analysis identified potential regulators of the CAM induction process, suggesting the possibility of introducing CAM features into drought-sensitive cultures. Finally, a cluster corresponding to epidermal bladder cells, a rare cell type specialized in salt sequestration, was identified. Further studies on the genes and pathways characterizing this cell type will undoubtedly improve our understanding of salt tolerance mechanisms in plants.