Various antioxidant responses to hyperthermia in anatomically different species of the genus Rosa

The heat and drought resistance of plants depend on their anatomical and biochemical features. In the present study, the adaptive features of three species of wild rose (Rosaceae, Rosales) under the short-term impact of high-temperature stress have been characterized. Plants of the species Rosa donetzica Dubovik, R. reversa Waldst. et Kit. and R. spinosissima L. were exposed to a temperature of 40 degrees C for 3 hours, following which peroxidase and superoxide dismutase activity, photosynthetic pigments and flavonoids’ content, and lipid peroxide oxidation level in the leaf were determined. In our investigation, the anatomical structure of leaves and drought resistance of three species of Rosa were studied. Xeromorphic features are the most expressed for R. reversa and R. spinosissima and almost absent for R. donetzica. It has been established that R. spinosissima is photophilous whereas R. donetzica is shade-tolerant. The relatively lower development of epidermic tissue in R. donetzica could probably contribute to more active destruction of the pigment complex under high temperature stress. The obtained data about changes in activity of peroxidase, superoxide dismutase, content of photosynthetic pigments and flavonoids, and level of lipid peroxidation indicate the low heat resistance of R. donetzica in comparison with the other two species. R. reversa, R. spinosissima were more tolerant to short-term hyperthermia. They showed faster antioxidant response, mainly due to the induction of peroxidase activity under stress. The species with the most expressed xerophytic features of anatomical structures have rapid antioxidant response and are more resistant to short-term hyperthermia. The induction of some activity of antioxidant enzymes "in reserve" is a less effective form of adaptation in wild roses. Such activation of enzymes is observed in plants with a more mesophytic structure. Flavonoids and superoxide dismutase were thermolabile to short-term influence of high temperature; therefore they play an insignificant role as antioxidants in the protecton against oxidative stress caused by high temperature stress in wild roses.