Variability of tolerance of Wild cherry clones to PEG-induced osmotic stress in vitro

The effects of drought simulated via osmotic stress induced by polyethylene glycol (PEG) in the growing medium were examined on two Wild cherry (Prunus avium L.) clones (6A and 8A) based on thirteen morphometric, physio-logical, and biochemical traits. The shoot tips were exposed to two PEG con-centrations (20 and 50 g L-1) in growing medium designed for micropropagation with axillary buds. The results showed that all morphological and physiological traits were significantly reduced, indicating a strong detrimental effect of in-creased PEG concentrations. The significant decline of radical scavenging ac-tivity against ABTS???+ and total content of flavonoids (TFC) and phenols (TPC) were recorded in both clones as a response to high PEG concentrations, whereas opposite trends were noticed for ferric reducing antioxidant power (FRAP). Clone 8A achieved better performance, having more intensive growth, higher multiplication percentage, higher values of carotenoids, more intense decrement of ABTS and increment of FRAP values compared to the clone 6A. The results of the principal component analysis indicate that parameter TFC/ TPC in both stem and leaves, as well as TFC in the stems, achieved the strong-est relation with morphometric parameters. Our results confirm the feasibility of in vitro evaluation of drought tolerance of Wild cherry, supporting further research on the variability of examined traits in this noble broadleaved tree species.