Boosting plant growth: fungal metabolites as biostimulants for growth promotion of Hypericum perforatum (L.)

Fungal culture filtrates have been reported in literature [1] as effective biostimulants for the plant growth. Studies on fungal strains metabolism showed that the metabolites produced in cocultures were clearly different from single cultures [2]. Therefore, Chaetomium globosum and Minimedusa polyspora showing characteristics with a high potential for plant growth promotion were incubated in single cultures and cocultures in two different culture media (Malt extract agar and Murashige & Skoog) for 15 days. The culture filtrates were applied to in vitro root cultures of Hypericum perforatum to test the effect in terms of biomass production. The culture filtrates were analysed by NMR-based metabolomics to identify the metabolites released by the fungi. Through the analyses were detected, identified and quantified about 30 low weight molecules belonging to the classes of: aminoacids (e.g. valine, GABA, phenylalanine), organic acid (e.g. acetic acid, fumaric acid), alcohols (e.g. ethanol, 2,3-butanediol), carbohydrates and other molecules. Several of the identified metabolites may be of interest for the plant growth stimulation. [1] Bagde et al., ‘Influence of culture filtrate of Piriformospora indica on growth and yield of seed oil in Helianthus annus’, Symbiosis, vol. 53, no. 2, pp. 83–88, May 2011. [2] Bertrand et al., ‘De Novo Production of Metabolites by Fungal Co-culture of Trichophyton rubrum and Bionectria ochroleuca’, Journal of Natural Products, vol. 76, no. 6, pp. 1157–1165, Jun. 2013.