TRENEVA, G., Y. MARKOVSKA, E. WOLFRAM and K. DANOVA, 2014. Effect of plant growth regulators on growth patterns and enzymatic antioxidant activities in Hypericum calycinum shoot cultures. Bulg. J. Agric. Sci., Supplement 1: 46-50 Hypericum calycinum L. (section Ascyreia) is a species of the Hypericum genus, relative to the medicinal plant H. perforatum (St. Jonn's worth). Unlike the widely studied H. perforatum, it is characterized by the lack of hypericins production. However, research has

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... aled its commensurable antidepressant activity, as compared with the latter species, and shown the presence of polyphenolics with marked radical scavenging activity. In order to develop an in vitro system with the potential of a novel source of bioactive constituent's characteristic for the Hypericum genus, we initiated in vitro cultures of H. calycinum. In the present work we studiy the effect of exogenous BA and IBA treatments on the developmental patterns, enzymatic and non-enzymatic antioxidant defence of hypericin non-producing Hypericum calycinum shoot cultures. It was shown that supplementation of PGR led to stimulation of phenylalanine ammonia-lyase and superoxide dismuthase, as well as non-enzymatic antioxidant glutathione. However, they inhibited glutathione reductase, as well as lowered the levels of fl avonoids, ascorbate and dehydroascorbate in comparison with plant growth regulators-free control. Further on, it was established that elevation of IBA concentration slightly stimulated axillary shoot formation and shoot length, but inhibited polyphenolic levels in vitro. These results are in agreement with our previous results of interrelations between biomass formation and polyphenolics production in other Hypericum species in vitro. An in vitro culture system optimization is in progress in order to increase biomass production and retain biosynthetic capacity of the species.