Recovery Dynamics of Photosynthetic Performance and Antioxidant Defense in Resurrection Plants Ramonda serbica and Ramonda nathaliae After Freezing-Induced Desiccation
Bekim Gashi | Fitim Kastrati | Gergana Mihailova | Katya Georgieva | Eva Popova | Erzë Çoçaj | Kimete Lluga-Rizani | Qëndrim Ramshaj
Resurrection plants such as Ramonda serbica and Ramonda nathaliae are gaining scientific attention due to their exceptional ability to withstand extreme drought and cold. This study is the first to evaluate the changes in photosynthetic activity, antioxidant defense, and the role of protective proteins during the early hours of recovery of these species after freezing-induced desiccation. Specimens collected from natural habitats where temperatures dropped below &minus:10 °:C were rehydrated under controlled conditions, and measurements were taken at multiple time points from 1 h up to 7 days after recovery. Both species demonstrated a gradual increase in photosynthesis, with the CO2 assimilation rate significantly improving after 24 h and reaching full restoration by day 7. This recovery aligned with increases in relative water content and stomatal conductance. Photosystem II efficiency was fully restored within 72 h. Notably, R. nathaliae exhibited higher thermal dissipation during stress than R. serbica. Antioxidant activity peaked between 1 and 3 h of rehydration and returned to baseline by day 7. Additionally, early rehydration stages triggered the accumulation of stress-related proteins such as dehydrins, early light-inducible proteins, small heat shock proteins, and fatty acid amide hydrolase. These results provide valuable insights into the desiccation&ndash:rehydration mechanisms of Ramonda species, demonstrating that they fully recover physiological functions within seven days and highlighting species-specific stress responses during early rehydration.
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