Influence of cryopreservation on the antioxidative activity ofin vitrocultivatedHypericumspecies

Abstract

Antioxidative activity of two in vitro cultivated Hypericum species – H. rumeliacum Boiss. and H. tetrapterum Fr. – was estimated after cryopreservation. Both species were successfully regenerated after a cryopreservation procedure performed by the vitrification method. H. tetrapterum did not manifest any significant oxidative stress-induced changes caused by low-temperature treatment. Conversely, a decrease in green pigments' content of H. rumeliacum was measured, particularly pronounced in chlorophyll b, which was accompanied by an increase of carotenoids in the regenerated plants.A strong increase of malone dialdehyde and H2O2 levels in H. rumeliacum tissues was detected. Superoxide dismutase activity was enhanced by 170%, as well as the catalase activity, which was 220% above the control. The same trend was observed in H. tetrapterum, although less pronounced – 143% increase of superoxide dismutase and 112% of catalase.Cryopreservation did not influence the phenol content in the examined plants, but it led to an increase of flavonoid content, especially in H. tetrapterum, by 237%. Total antioxidant activity in regenerated H. tetrapterum varied around the control level, but it was increased in H. rumeliacum. The free proline content in H. tetrapterum remained almost unaffected after freezing, as opposed to H. rumeliacum, where a strong increase of proline content (208% above the control) occurred. An electrolyte leakage from the cells of H. rumeliacum regenerated after cryopreservation was also registered, albeit not significant.

Analyzing effect of altitudinal variation in Enzymatic antioxidants ofColeus forskohliifrom Uttarakhand, India

“…Higher APX activity at high altitudes may be to scavenge the plants from high H2O2 level (Kaur et al, 2016). High intensity of UV radiation and the low temperature leads to a higher oxidative stress with H2O2 production at higher altitudes (Georgieva et al, 2014). The increasing activity of GR and PPO at higher altitude may be attributed to the defense mechanism of plant by H2O2 decomposition.…”

Cryopreservation ofRosa hybridacv. Helmut Schmidt by PVS2 vitrification method usingin vitrofragmented explants (IFEs)

“…Helmut Schmidt was measured as an indication of oxidative stress encountered during the PVS2 vitrification method. According to the authors [66], the successive steps of cryopreservation bring about ROS-mediated oxidative stress inducing the increases in SOD activity that can elevate stress tolerance in plant cells. SOD activity of cryopreserved IFEs of Rosa hybrida cv.…”

Conservation Strategies in the Genus Hypericum via Cryogenic Treatment

“…On the other hand, no significant differences in the physiological state of post-cryogenic regenerants in another Hypericum representative – H. tetrapterum – were noticed ( Georgieva et al, 2014 ). Although the lower degree of oxidative damage expressed by both, enzymatic and non-enzymatic physiological markers might suggest that the species is more tolerant to freezing, the potential of the species to withstand cryogenic treatment was much reduced when compared to H. perforatum.…”

“…Apart from the species-specific structural modifications observed in post-cryogenic regenerants of Hypericum spp., differences in the extent of oxidative damage are also documented at physiological level. Along with the natural enzymatic defense represented by ROS-scavenging enzymes that are known to accumulate in cryopreserved cells and tissues ( Reed, 2014 ; Chen et al, 2015 ), the non-enzymatic physiological markers including chlorophylls, carotenoids, proline, phenolics, and flavonoids have been investigated ( Skyba et al, 2010 ; Danova et al, 2012 ; Georgieva et al, 2014 ).…”

“…In H. rumeliacum , markedly increased both, enzymatic and non-enzymatic antioxidant activities indicating an extensive ROS-production persisted during the regeneration phase for several months ( Danova et al, 2012 ). While post-cryogenic regenerants of H. rumeliacum displayed several morphological and physiological deviations comprising shorter stems, decreased number of leaves, poorly developed root system and slower growth rate ( Georgieva et al, 2014 ), no substantial modifications in the developmental pattern of H. perforatum were observed ( Skyba et al, 2012 ). When compared with H. rumeliacum , the ability of H. perforatum to eliminate the phenotypic expression of an increased oxidative status, substantially lower LT 50 value and increased post-cryogenic regeneration potential ( Petijová et al, 2014 ) indicates H. perforatum as more tolerant to the freezing process.…”