Enhanced inulin production by hairy root cultures of Cichorium intybus in response to Pi and Fe starvation

Cichorium intybus is rich in inulin and has several pharmacological applications. Hairy roots culture is a valuable biotechnological tool used to produce plant secondary metabolites. Agrobacterium rhizogenes-mediated genetic transformation of chicory to hairy roots was investigated using Agrobacterium Strains A4, A13, A7, and ATCC15834. Several hairy roots were tested, from which 17 lines were selected based on their fast-growing characteristics. Results of PCR analysis revealed foreign DNA integration into the selected transgenic hairy root lines. Finally, four Adventitious roots that contained the highest ratio of total sugar to total weight (µg/gr DW), were selected. This study investigated the effects of various levels of minerals and sucrose on the production of inulin in Cichorium hairy root culture. Different levels of sucrose, phosphate (Pi) and Iron (Fe) were evaluated, separately. It was found that an increase in sucrose levels from 3 to 5% could decrease the root growth; however, 60 g/l sucrose remarkably enhanced the inulin production rate in all the examined lines. The highest biomass was achieved by applying 3.75 mM Pi but it ended in the decreasing the inulin content per unit weight. In contrast, the highest inulin accumulation and the lowest amount of biomass were observed in 0.5 mM Pi. Fe starvation caused the biomass decrease and a significant increase in inulin accumulation. Results of this study suggest a successfully optimized culture medium to initiate the induction of Cichorium intybus hairy root cells to produce inulin as a valuable medicinal secondary metabolite.