Periodic Reporting for period 1 - MICROMETABOLITE (“MICROMETABOLITE” – Research Training Network on the Microbial Enhancement of Bioactive Secondary Metabolite Production in Plants)
Reporting period: 2017-05-01 to 2019-04-30
Plant-associated microorganisms such as endophytic bacteria and fungi (which reside inside living plants) and soil-borne, mycorrhizal fungi are essential to optimum plant health and growth. They are physiologically tightly interlinked with their hosts, and, hence, may induce or modulate the production of plant secondary metabolites. Microbial activities that enhance plant nutrient uptake may influence major synthesis pathways, in addition to external influences from herbivores, pathogens, and the abiotic environment. Moreover, endophytic bacteria and fungi themselves are known as producers of various plant-derived bioactive compounds.
In MICROMETABOLITE, we extract from the roots of Lithospermum and Alkanna plants belonging to the Boraginaceae family various naphtoquinone derivatives (e.g. alkannin and shikonin, A/S). These compounds have shown positive effects in tissue regeneration and wound healing and have proven antimicrobial, anti-inflammatory, anti-HIV-1, and anti-cancer activities. Boraginaceae-derived compounds are already used in various cosmetics and medicinal products, and there is growing interest in expanding the range of pharmaceutical application. However, synthesis in plant cultivation systems is often inconsistent and gives low yields as compared with wild plants growing at their native sites, which presently limits commercialization.
Regarding the microbial communities associated with A/S producing plants, Burkholderiaceae, Pseudomonadaceae and Xanthobacteriaceae were the most common bacterial taxax while Plectosphaerella, Penicillium, Fusarium and Trichoderma sp. were the most common fungal taxa.
In several isolation campaigns, wild A. tinctoria plants and rhizosphere soil were sampled in Thessaloniki and in Athens. Fungal endophytes were isolated and together with Glomeromycota AMF strains were tested for plant growth promotion and secondary metabolite promotion in Echium vulgare.The biological activity of A/S and derivatives was evaluated, among others, in terms of cytotoxicity and induction/inhibition of adipogenesis, and A/S were used as active compounds in cell-based tissue engineering scaffolds. Furthermore, we started to establish novel in vitro and in vivo propagation systems of Boraginaceae plants and associated them with arbuscular mycorrhizal fungi (AMF) and bacteria.