Bruňáková Katarína, Čellárová Eva
Institute of Biology and Ecology, Faculty of Science, Pavol Jozef Šafárik University in Košice Košice, Slovakia.
Front Plant Sci. 2016 Apr 27;7:558. doi: 10.3389/fpls.2016.00558. eCollection 2016.
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.
在金丝桃属植物中，低温保存为维护显著的生物多样性提供了一种策略，这种生物多样性源于其在形态和植物化学特征方面存在的种间和种内巨大变异性。因此，长期低温储存是保护濒危和受威胁金丝桃属物种或具有独特特性的新体细胞克隆变异体遗传资源的合适工具。该属的许多代表植物是具有重要药理活性的聚酮化合物的生产者，即萘二蒽酮和间苯三酚。作为众多离体收集物的一部分，几乎遍布全球的贯叶连翘——圣约翰草——已成为应用生物技术方法的合适模型系统，为次生代谢产物生产的传统方法提供了有吸引力的替代方案。高效冷冻保存的必要条件包括高存活率以及从冷冻保存的细胞再生的植物具有不变的生化特征。了解低温处理后贯叶连翘细胞恢复所必需的关键过程，有助于建立适用于多种金丝桃属物种的冷冻保存方案。其中，一些特有分类群因其独特的特征或尚未揭示的生物活性化合物谱而备受关注。在本综述中，介绍了传统两步法和基于玻璃化的冷冻保存技术在金丝桃属植物恢复率和生物合成能力方面的最新进展。讨论了被确定对低温后成功恢复至关重要的低温前处理。作为遗传倾向的一部分，指出了冷冻耐受性作为低温后成功恢复的必要前提条件。此外，概述了冷胁迫对调节萘二蒽酮生物合成的有益影响。
