1- Evolution of Photosynthesis: The Story Bryophytes can tell
The colonization of land posed significant challenges to early plants, particularly regarding light stress and water availability. As the earliest land plant lineage, bryophytes (mosses, liverworts and hornworts) are crucial for understanding the evolution of photosynthetic regulation and its adaptation to land environment. We are focusing on how different mechanisms for regulation of photosynthesis adapted during evolution:
- NPQ & The Xanthophyll Cycle: Mosses like Physcomitrium patens use a dual system (LHCSR and PSBS) to dissipate excess light as heat. This is fueled by the conversion of violaxanthin to zeaxanthin, protecting the machinery from oxidative stress
- Flavodiiron Proteins (FLV): This ancestral “safety valve” prevents Photosystem I over-reduction by diverting excess electrons to reduce oxygen back to water, a mechanism lost in vascular plants but vital for cyanobacteria, algae, bryophyte and gymnosperm resilience
2- Mitochondrial Respiration & Metabolic Crosstalk
Mitochondrial respiration is essential for energy production during the night, but it is also a critical metabolic partner to photosynthesis. Mitochondrion acts as an electron sink, accepting excess reducing power from the chloroplast. Using the moss Physcomitrium patens as a model organism we are investigating mutants depleted in respiratory complexes, not viable in vascular plants, to understand the impact of respiration in photosynthetic metabolism
To study this inter-organelle coordination, we use molecular physiology approaches together with genetically encoded biosensors that allow us to measure real-time ATP concentrations within specific compartments (cytosol, chloroplast, or mitochondria), revealing how plants maintain energy homeostasis under changing conditions