Organogenesis and embryogenesis in several hypericum perforatum genotypes

St John’s wort (Hypericum perforatum) is a valuable plant used as a herbal remedy or in phytopharmaceutical drugs to treat a variety of physical ailments. Much research has been performed to study the biochemical production of secondary metabolites of in vitro cultured plants or organs. However, all of these studies have looked at the regeneration of plants from explants in only one genotype. In addition, no study has revealed the mechanism of plant regeneration in H. perforatum, i.e. organogenesis or somatic embryogenesis. We found that different genotypes Helos, Topas, Elixir, and Numi responded similarly to regeneration medium. The regeneration responses (i.e. callus, root, or shoot production) of identical explants from different genotypes were similar. However, the source of explant material (leaves, hypocotyls, and roots) from the same genotype had significant effects on the response to media and plant regeneration frequency. Using scanning electron microscopy and light microscopy, the progress of organogenesis and embryogenesis under similar culture conditions was recorded. Root segments were the most responsive explants, producing the maximum number of shoots per explant of all the genotypes.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/AGR/40 283/2001, SFRH/BPD/17102/2004

A perspective on Hypericum perforatum Genetic transformation

Hypericum perforatum (St John's wort) is a reservoir of diverse classes of biologically active and high value secondary metabolites, which captured the interest of both researchers and the pharmaceutical industry alike. Several studies and clinical trials have shown that H. perforatum extracts possess an astounding array of pharmacological properties. These properties include antidepressant, anti-inflammatory, antiviral, anti-cancer, and antibacterial activities; and are largely attributed to the naphtodianthrones and xanthones found in the genus. Hence, improving their production via genetic manipulation is an important strategy. In spite of the presence of contemporary genome editing tools, genetic improvement of this genus remains challenging without robust transformation methods in place. In the recent past, we found that H. perforatum remains recalcitrant to Agrobacterium tumefaciens mediated transformation partly due to the induction of plant defense responses coming into play. However, H. perforatum transformation is possible via a non-biological method, biolistic bombardment. Some research groups have observed the induction of hairy roots in H. perforatum after Agrobacterium rhizogenes co-cultivation. In this review, we aim at updating the available methods for regeneration and transformation of H. perforatum. In addition, we also propose a brief perspective on certain novel strategies to improve transformation efficiency in order to meet the demands of the pharmaceutical industry via metabolic engineering.GF and PS are financed from the BIOTALENT project (GA621321) funded by the European Union Seventh Framework Programme (FP7) ERA Chairs Pilot Call and co-financed by funds allocated for education through project no W26/7.PR/2015 [GA 3413/7.PR/2015/2] for the years 2015-2019. This work was partially supported by Fundacao para a Ciencia e a Tecnologia (FCT) project (PTDC/AGR-GPL/119211/2010). WEE acknowledges the financial support provided by the FCT (SFRH/BD/52561/2014), under the Doctoral Programme "Agricultural Production Chains-from fork to farm" (PD/00122/2012).info:eu-repo/semantics/publishedVersio

Hypericum sp.: essential oil composition and biological activities

Phytochemical composition of Hypericum genus has been investigated for many years. In the recent past, studies on the essential oils (EO) of this genus have been progressing and many of them have reported interesting biological activities. Variations in the EO composition of Hypericum species influenced by seasonal variation, geographic distribution, phenological cycle and type of the organ in which EO are produced and/or accumulated have also been reported. Although many reviews attributed to the characterization as well as biological activities of H. perforatum crude extracts have been published, no review has been published on the EO composition and biological activities of Hypericum species until recently (Crockett in Nat Prod Commun 5(9):1493–1506, 2010; Bertoli et al. in Global Sci Books 5:29–47, 2011). In this article, we summarize and update information regarding the composition and biological activities of Hypericum species EO. Based on experimental work carried out in our laboratory we also mention possible biotechnology approaches envisaging EO improvement of some species of the genus.Fundação para a Ciência e a Tecnologia (FCT) - project PTDC/AGR AAM/70418/2006, SFRH/BD/ 13283/2003

Hypericins as Potential Leads for New Therapeutics

70 years have passed since the first isolation of the naphthodianthrones hypericin and pseudohypericin from Hypericum perforatum L. Today, they continue to be one of the most promising group of polyphenols, as they fascinate with their physical, chemical and important biological properties which derive from their unique chemical structure. Hypericins and their derivatives have been extensively studied mainly for their antitumor, antiviral and antidepressant properties. Notably, hypericin is one of the most potent naturally occurring photodynamic agents. It is able to generate the superoxide anion and a high quantum yield of singlet oxygen that are considered to be primarily responsible for its biological effects. The prooxidant photodynamic properties of hypericin have been exploited for the photodynamic therapy of cancer (PDT), as hypericin, in combination with light, very effectively induces apoptosis and/or necrosis of cancer cells. The mechanism by which these activities are expressed continues to be a main topic of discussion, but according to scientific data, different modes of action (generation of ROS & singlet oxygen species, antiangiogenesis, immune responces) and multiple molecular pathways (intrinsic/extrinsic apoptotic pathway, ERK inhibition) possibly interrelating are implicated. The aim of this review is to analyse the most recent advances (from 2005 and thereof) in the chemistry and biological activities (in vitro and in vivo) of the pure naphthodianthrones, hypericin and pseudohypericin from H. perforatum. Extracts from H. perforatum were not considered, nor pharmakokinetic or clinical data. Computerised literature searches were performed using the Medline (PubMed), ChemSciFinder and Scirus Library databases. No language restrictions were imposed

The use of natural pressurised forced ventilation in plant micropropagation

A new, uncomplicated system for the forced ventilation of plants and cultures has been investigated in terms of both its efficiency of ventilation and its effects on the growth and physiology of various plant species, including cauliflower, tobacco, Annona (custard apple) and potato. This new system, which has no moving parts or artificial energy requirement, provides a sustained, pressurised stream of sterile, humidified air (RH = 70-94%) driven by humidity-induced diffusion. This process depends upon the maintenance of a gradient of water vapour across a microporous partition for inducing the diffusion of air into the apparatus. Flows up to 5 cm³ min¯¹ can be produced and the atmosphere in a 60 cm³ culture vessel can be renewed every 12 min Compared to the standard conventional diffusive method of ventilation, e. g. by capping the vessel with a polypropylene disc, this new system has proved to be 18X more efficient in removing accumulated ethylene and in keeping CO₂ and O₂ levels in culture vessels close to atmospheric. This forced ventilation system has also been shown to be very effective in the in vitro cultivation of seedlings or cuttings of cauliflower, tobacco, Annona and potato for improving growth and preventing symptoms of vitrification such as leaf epinasty, reduction of leaf area and production of abnormal stomata. In potato cuttings the induction and production of microtubers have been promoted and the growth of abnormal callus prevented. In Annona cuttings flower bud production, leaf and shoot growth and micropropagation have been promoted and leaf and flower bud abscission have been reduced. In cauliflower, tobacco and Annona the leaf chlorophyll contents, rates of photosynthesis and yields were improved by this forced ventilation. These beneficial effects have been variously attributed to the efficient removal of ethylene, the maintenance of near to atmospheric levels of CO₂ and O₂ by day and night and to the reduction of humidity levels in the vessels to below 100% RH. It is hoped that this new ventilation system, which is comparatively inexpensive and requires very little maintenance might have some useful applications in the field of tissue culture and perhaps particularly in developing countries