Agrobacterium rhizogenes mediated transformation, initiation and multiplication of hairy roots in Spilanthes acmella Murr.

Spilanthes acmella is an important medicinal plant that belongs to the family Asteraceae. Traditionally, this plant has been used for years to cure toothaches, stammering, stomatitis and many other ailments. This plant is an important source of various medicinally important secondary metabolites like phenolics, coumarin, spilanthol, scopoletin, triterpenoids etc. The present study was carried out with the objective to transform this plant with Agrobacterium rhizogenes to initiate the hairy roots formation. This study demonstrated the transformation, initiation and multiplication of hairy roots from nodal segments and leaf explants taken from field grown and in vitro developed S. acmella plants. The hairy roots produced from different explants were white, slender, showed negative geotropism and lateral branching. PCR analysis of hairy root was performed that confirmed the bacterial transformation. Among the field grown and in vitro grown plants, the explants from the in vitro grown plants gave a high percentage of root induction. Nodal segments from in vitro grown plant gave 90% hairy root induction and leaf segments from in vitro grown plants with petiole gave the highest rate of root induction which was 92%. Nodal segments from field grown plants gave 85% and the leaves from field grown plants gave 80% of hairy root induction. This study offers great potential to establish the protocol for hairy root induction which can be used as an alternative source for the continuous production of this plant’s important secondary metabolites and active biocompounds.