Fungal bioresources to increase secondary metabolites production: elicitation effect on Chicorium intybus hairy roots by Chaetomium globosum culture filtrate

Plant secondary metabolites are of great interests as potential drugs, nutraceuticals and food additives. Tissue culture represents an effective strategy for large-scale production of desired compounds. Several studies reported that transformed root cultures show a rapid growth, uniformity, stability and capacity to synthesize higher levels of secondary metabolites than those found in normal roots, making them particularly convenient for this purpose. Among the various biotechnological strategies, elicitation represents one of the most effective and widely employed for the induction or enhancement of secondary metabolites biosynthesis in in vitro plant tissue cultures. Since in nature biologically active compounds in many cases are produced as a part of the response to external stress such as the presence of microorganisms in the environment, fungi and their metabolites released in culture medium represent effective elicitors. Therefore, we tested Chaetomium globosum Kunze (Fig. 1a), a saprotrophic / endophytic Ascomycete, for its potential as elicitor of Chicorium intybus L. hairy roots. The fungal strain was incubated for 14 days in Malt extract broth (Fig. 1b) and the culture filtrate effect was tested applying two different concentrations (5ml/L and 10ml/L) to elicit in vitro cultures of Chicorium intybus hairy roots in liquid Murashige & Skoog medium (Fig. 2a). After 7 days of growth following the elicitation the effect in terms of stimulation of metabolites synthesis, was evaluated through 1H-NMR analysis. Effects on biomass production were evaluated through fresh weight measurements. Furthermore, a subsample of roots from each sample was scanned and analysed with the image analysis software SmartRoot to acquire specific root length and root tissue density measures to evaluate effects on roots morphology. In addition, the culture filtrate used for elicitation was analysed by 1HNMR- based metabolomics to identify the metabolites released by the fungus.