Effect of nano-elicitors on the production of some secondary metabolites in hairy roots of Galega (Galega officinalis L.)

Galega (Galega officinalis L.) from the leguminous family is used to treat diabetes. Hairy root culture is a valuable system for the production of secondary metabolites on a large scale. The use of elicitors in plant tissue and cell culture is one of the most efficient biotechnological tools for inducing biosynthesis and accumulation of secondary metabolites. This study aimed to investigate the effect of iron, silver, and silicon nanoparticles on growth and galegine content in hairy roots of G. officinalis.

In this study, induction of hairy roots in leaf, cotyledon, and hypocotyl explants of G. officinalis was performed using the A4 strain of Rhizobium rhizogenes, and the effect of different concentrations of silver, silicon, and iron oxide nano-elicitors on growth and galegine, phenol, and flavonoids content of hairy roots was investigated.

The highest rate of root induction was obtained in leaf explants with an average of 5 roots per explant. The highest root growth rate belonged to the treatments with 50 and 100 mg l-1 silicon nanoparticles for 72 h. Application of all levels of silver, iron, and silicon elicitors for 36 h resulted in a significant increase in the total phenol content of hairy roots. Thus that the highest amount of total phenol was obtained in 36 h treatment of roots with a concentration of 100 mg l-1 of silicon nanoparticles without significant difference with 10 and 20 mg l-1 silver nanoparticles. Also, the highest amount of total flavonoids was obtained at 200 mg l-1 iron nanoparticles for 36 h; and the highest content of galegine was obtained in the treatment of roots with 10 and 20 mg l-1 silver, and 100 mg l-1 silicon nanoparticles for 36 h.

The appropriate type and concentration of elicitors is an effective factor in the response of hairy roots to nano-elicitors. The highest yield of galegine (17.55 mg) was obtained in the treatment of roots with 50 mg l-1 of silicon nanoparticles for 72 h. This can be attributed to both better growth of hairy roots and high galegine content at this treatment.