Decoding the physicochemical basis of resurrection: the journey of lichen Flavoparmelia caperata through prolonged water scarcity to full rehydration.

Desiccation tolerance is a complex phenomenon observed in the lichen Flavoparmelia ceparata. To understand the reactivation process of desiccated thalli, completely dried samples were rehydrated. The rehydration process of this lichen occurs in two phases. The first phase, characterized by rapid rehydration, involves the conversion of non-functional reaction centers (RCs) into functional PSII RCs, and the accumulation of ROS along with the increment in SOD antioxidant enzyme. These coordinated mechanisms initiate the light reaction of photosynthesis by forming active light-harvesting complexes (LHCs). This adaptation ensures efficient recovery, as evidenced by specific energy fluxes (ABS/RC, TR/RC, ET/RC, and DI/RC), phenomenological fluxes (ABS/CS, TR/CS, ET/CS, and DI/CS), quantum efficiencies (ФP, ФE, and ФD), primary and secondary photochemistry, photochemical and non-photochemical quenching, and performance index, highlighting the essential role of rapid water uptake in restoring turgor pressure for cell structure and function maintenance. The interconnected network of antioxidant defenses, including catalase (CAT) and peroxidase (POD), underscores the plant's ability to cope with oxidative stress during resilience. The acid phosphomonoesterase (PME) enzymatic activity corresponds to its role in releasing phosphate for essential cellular functions and post-rehydration thallus growth. The activity of CAT, GPOD, and PME signifies the gradual reactivation of lichen F. caperata. Moreover, the investigation into chlorophyll a fluorescence emphasizes the efficient reactivation of the photosynthetic process in F. caperata. In conclusion, lichen F. caperata demonstrates significant potential for desiccation tolerance through the rapid transformation of chloroplasts, chlorophylls, and PSII RCs from their inactive to active states upon rehydration. This research not only enhances our understanding of desiccation tolerance in resurrection plants but also highlights the importance of lichens, particularly F. caperata, as valuable models for studying plant resilience in challenging environments.