Hairy Roots as Producers of Coumarins, Lignans, and Xanthones

Despite the great structural diversity, plant lignans, coumarins, and xanthones share numerous biological activities, ranging from antimicrobial, anti-inflammatory, and antioxidant to antineoplastic and neuroprotective. The compounds, products of the shikimic acid biosynthetic pathway, also play an important role in plant-environment interactions. In a search for sustainable and renewable sources of these valuable plant products, numerous in vitro culture systems were investigated, including hairy root cultures. The Rhizobium rhizogenes-transformed root cultures of over 40 plant species representing 17 families of the plant kingdom were studied in this respect. The present review focuses on the hairy roots that may be efficient producers of valuable plant products with the prospect of use in the pharmaceutical, food, or cosmetics industry. In vitro culture systems based on hairy roots, which were used to elucidate the biosynthesis pathways of the high-added-value plant compounds, were also considered.