Conservation Strategies in the Genus Hypericum via Cryogenic Treatment

Abstract

In the genus Hypericum, cryoconservation offers a strategy for maintenance of remarkable biodiversity, emerging from large inter- and intra-specific variability in morphological and phytochemical characteristics. Long-term cryostorage thus represents a proper tool for preservation of genetic resources of endangered and threatened Hypericum species or new somaclonal variants with unique properties. Many representatives of the genus are known as producers of pharmacologically important polyketides, namely naphthodianthrones and phloroglucinols. As a part of numerous in vitro collections, the nearly cosmopolitan Hypericum perforatum – Saint John’s wort – has become a suitable model system for application of biotechnological approaches providing an attractive alternative to the traditional methods for secondary metabolite production. The necessary requirements for efficient cryopreservation include a high survival rate along with an unchanged biochemical profile of plants regenerated from cryopreserved cells. Understanding of the processes which are critical for recovery of H. perforatum cells after the cryogenic treatment enables establishment of cryopreservation protocols applicable to a broad number of Hypericum species. Among them, several endemic taxa attract a particular attention due to their unique characteristics or yet unrevealed spectrum of bioactive compounds. In this review, recent advances in the conventional two-step and vitrification-based cryopreservation techniques are presented in relation to the recovery rate and biosynthetic capacity of Hypericum spp. The pre-cryogenic treatments which were identified to be crucial for successful post-cryogenic recovery are discussed. Being a part of genetic predisposition, the freezing tolerance as a necessary precondition for successful post-cryogenic recovery is pointed out. Additionally, a beneficial influence of cold stress on modulating naphthodianthrone biosynthesis is outlined.

Stress and defense responses in plant secondary metabolites production

“…Exposure of the plant cells, tissue or organ to cryopreservation may induce changes that include desiccation, osmotic injury and low temperature-induced stresses [186]. The technique was found ineffective in the production of phenols but, enhanced the biosynthesis of flavonoids in the cryopreserved and regenerated species of Hypericum [184, 186] while Rhodiola crenulata calli showed enhanced survival when pre-treated with 0.1 µM melatonin [187]. When Taxus chinensis cell suspension culture were cryo-preserved for up to 30 days, good recovery of the cultures with retained stability in paclitaxel biosynthetic capacity was observed in comparison to cultures maintained through regular subculture [188].…”

“…When Taxus chinensis cell suspension culture were cryo-preserved for up to 30 days, good recovery of the cultures with retained stability in paclitaxel biosynthetic capacity was observed in comparison to cultures maintained through regular subculture [188]. On the other hand, cryopreservation of H. tetrapterum shoot cultures did not alter biosynthesis of phenol but enhanced the yield of flavonoids, with effect on growth, biochemical and cellular processes [184, 186]. The shoot tip of H. perforatum cryopreserved showed genetic stability with sustained production of hypericin after recovery of meristems, and at levels similar to the unfrozen control [189, 190].…”

Integration of in vitro and in silico perspectives to explain chemical characterization, biological potential and anticancer effects of Hypericum salsugineum: A pharmacologically active source for functional drug formulations

“…Among them, H . perforatum L. is the best-known species, used in traditional medicine and in the preparation of dietary supplements [ 1 , 2 ]. Several authors have recently investigated potential medicinal applications of other Hypericum species, such as H .…”

Comparative Transcriptome Reconstruction of Four Hypericum Species Focused on Hypericin Biosynthesis

“…The content of phloroglucinol (hyperforin), naphtodianthrones (protopseudohypericin, pseudohypericin, protohypericin, and hypericin) and their putative precursor emodin in the leaves of Hypericum species was determined by high-performance liquid chromatography (HPLC). The extracts were prepared and analyzed according to Bruňáková and Čellárová (2016) in three replicates. The compounds were identified and quantified by the Agilent Infinity 1,260 HPLC system (Agilent Technologies, Palo Alto, CA, USA) equipped by a diode array detector.…”