Elicitation: A biotechnological tool for enhanced production of secondary metabolites in hairy root cultures

Abstract

Elicitation is a possible aid to overcome various difficulties associated with the large‐scale production of most commercially important bioactive secondary metabolites from wild and cultivated plants, undifferentiated or differentiated cultures. Secondary metabolite accumulation in vitro or their efflux in culture medium has been elicited in the undifferentiated or differentiated tissue cultures of several plant species by the application of a low concentration of biotic and abiotic elicitors in the last three decades. Hairy root cultures are preferred for the application of elicitation due to their genetic and biosynthetic stability, high growth rate in growth regulator‐free media, and production consistence in response to elicitor treatment. Elicitors act as signal, recognized by elicitor‐specific receptors on the plant cell membrane and stimulate defense responses during elicitation resulting in increased synthesis and accumulation of secondary metabolites. Optimization of various parameters, such as elicitor type, concentration, duration of exposure, and treatment schedule is essential for the effectiveness of the elicitation strategies. Combined application of different elicitors, integration of precursor feeding, or replenishment of medium or in situ product recovery from the roots/liquid medium with the elicitor treatment have showed improved accumulation of secondary metabolites due to their synergistic effect. This is a comprehensive review about the progress in the elicitation approach to hairy root cultures from 2010 to 2019 and the information provided is valuable and will be of interest for scientists working in this area of plant biotechnology.

Signal Molecules Crosstalk and the Critical Role of Jasmonic Acid in Triterpenoid Synthesis Inducement of Aspergillus Niger Elicitor in Suspension Cultured Cyclocarya Paliurus Cells

“…Their data also showed that NO quenching suppressed the H 2 O 2 synthesis, and exogenous NO addition increased the H 2 O 2 accumulation, however according to our results, the change of NO concentration had no effect on the H 2 O 2 synthesis. According to the schematic representation of action mode of elicitor in plant cell given by Halder et al [20], NO synthesis was the downstream event of the ROS burst under elicitation, which coincided with our conclusion. These different phenomena and results may be caused by plant species differences or other unknown reasons, and further studies are still needed.…”

“…Elicitation is one of the most effective ways to stimulate the secondary metabolite synthesis in the plant cell, and therefore is now widely employed to induce novel metabolites or enhance the accumulation of the target metabolites in the plant cell, tissue and organ cultures [20]. According to chemical property, the elicitors are normally classi ed into two types, including abiotic elicitors (e.g.…”

“…fungal extracts, bacterial extracts and chitin) [21,22]. These elicitors can trigger defense or stress-induced responses at a low concentration, which can further regulate the expression level of some biosynthesis pathway genes via complex signal transduction networks and nally promote the synthesis of secondary metabolites [20]. Fungal extract is one of the most effective and studied elicitors in the last three decades.…”

An Extract of Transgenic Senna obtusifolia L. hairy roots with Overexpression of PgSS1 Gene in Combination with Chemotherapeutic Agent Induces Apoptosis in the Leukemia Cell Line

“…A wide range of pharmaceutical proteins for therapeutic use is currently in different phases of clinical trials [32]. It is also possible to produce secondary metabolites with high yields using routine techniques of in vitro plant cell and tissue cultures, which are becoming an attractive alternative to traditionally-used, naturally occurring plant material [33,34].…”

Optimization of conditions for the induction of Tagetes patula L. hairy roots

“…One of the sources of secondary metabolites is the hairy roots culture, the growth of which is initiated by the transfer of the Rol gene of the soil bacterium Agrobacterium rhizogenes to the plant cell genome (Bensaddek et al, 2008;Ono and Tian, 2011;Vladimirov et al, 2015;Dhiman et al, 2018). The root culture obtained in this way has genetic and biochemical stability, unlimited growth rate in growth regulator-free media, short doubling times, high biosynthetic activity and responsiveness to elicitor treatments as well as ecological purity of the plant raw materials (Vdovichenko et al, 2007;Kuzovkina and Vdovichenko, 2011;Khan et al, 2018;Halder et al, 2019). Over the past decades, there was a lot of data on the development of effective protocols for inducing hairy root cultures that can synthesize biologically active substances (Giri et al, 2001;Saleh and Thuc, 2009;Saravanakumar et al, 2012;Farag and Kayser, 2015;Belabbassi et al, 2016;Patra and Srivastava, 2016).…”