In vitro micropropagation and hairy root induction for astragaloside IV production in Astragalus membranaceus var. mongholicus

Abstract

Abstract Astragalus membranaceus var. mongholicus, is an important natural source of bioactive constituents. Pharmacological and clinical studies of secondary metabolites have confirmed that A. membranaceus has diverse biological functions. Plant tissue culture-based techniques and hairy root and adventitious root cultures are often used as practical platforms for the exploitation of biochemical compounds from medicinal plants. In this study, micropropagation of A. membranaceus was optimized for rapid proliferation, and hairy roots were induced by three strains of Agrobacterium rhizogenes (A4, A13, and MSU), on two leaf explant ages (10- and 20-day old), and three inoculation times (10, 20, and 30 min). In addition, the effects of three concentrations (100, 250, and 500 µM L− 1) of salicylic acid (SA) and methyl jasmonate (MJ) on astragaloside IV accumulation in A. membranaceus hairy roots were investigated. The highest number and length of branches were obtained on MS medium supplemented with 1 mg L− 1 BAP. Strain A13 caused the highest rate of induction of hairy root in leaf explants. In addition, since the age of explants had a significant effect on hairy root formation, the youngest explants obtained the highest number and longest hairy roots. Results showed that inducers of methyl jasmonate and salicylic acid elicitors could effectively stimulate the content of astragaloside. Our study showed that treating hairy root cultures with 250 µM MJ or 500 µM SA effectively increased astragaloside-IV accumulation in A. membranaceus hairy roots. Therefore, The findings provide valuable insights into optimal conditions for increasing large-scale production of astragaloside-IV such as industrial production in bioreactors.