A joint seminar of the section Systematics, Biodiversity & Evolution of Plants, the Botanische Staatssammlung München and the Botanical Garden München-Nymphenburg
When? Wednesdays at 1:15 pm (during the semester, unless specified otherwise).
Where? Room 109 Botanical Institute, Menzinger Str. 67, 80638 München.
Dr. Katharina Schiller, University of Bielefeld, Bielefeld, Germany.
Regulation of Crassulacean Acid Metabolism on the DNA, Transcript, and Protein Level in Kalanchoë species
Host: Dr. Renata Callegari Ferrari
Crassulacean acid metabolism (CAM) is a water-saving add-on metabolism making photosynthesis more water use efficient. With the changing climate and growing world population, CAM is a promising avenue for engineering more drought resistant crops. However, the regulation of this trait is still not fully unraveled and no master regulator is known for transcriptional reprogramming upon induction of CAM. In my PhD thesis, I analyzed the regulation of CAM on multiple levels. In the seminar, I will give an overview of the regulatory layers and molecular methods used to study the regulation of CAM in general and drought-inducible CAM in Kalanchoë gracilipes in particular.
While differences of the CAM-related transcript levels between day and night are well described for many CAM species, proteomics analyses of Kalanchoë laxiflora show that these differences barely translate to the protein level. Posttranslational modifications (PTMs) like phosphorylation carry an immense potential to regulate more CAM proteins than the known example of PPC phosphorylation. Phosphoproteomic analysis in K. laxiflora reveals more candidate regulatory phosphorylations and phylogenetic analysis of the conservation of potentially modified amino acids show the potential of PTMs in the regulation of CAM across independent origins.
Finally, I will focus on the role of the transcription factor KgABF1/2 in the role of CAM induction upon drought in Kalanchoë gracilipes. Using RNA sequencing and DNA Affinity Purification sequencing (DAPseq), upregulation of CAM genes at specific times of day can be connected to direct binding of the transcription factor to promoters of these CAM genes. This indicates integration of CAM induction into the existing drought regulon.
Altogether, the results shift the focus from analysis of transcript abundancies to protein abundance, modifications, adaptations, and interactions of transcription factor proteins with promoters of target genes and allow for a more thorough understanding of the complexity of CAM regulation and induction.