Culture conditions for induction of hairy roots in medicinal plant Coleus blumei

Hairy root induction in plants has affected by many factors including type, age of explant and bacterial strain. In the present study, the effects of bacterial strains (A4, C58, 15834 and GM), two concentrations (OD600= 0.5 and 1) and two explants (leaves and stems) in hairy root induction of C. blumei were investigated. According to the results of this study, the four strains showed different abilities to induce hairy root. The highest percent of induced roots (85%) was seen in explant treated with C58 strain, at OD600= 0.5 and the lowest induced roots (5%) by using of GM strain at OD600 = 1 and stem explants observed. The highest number of hairy roots per explant (12.94) has shown in leaf explant of leaf inoculated with C58 strain at (OD600 = 0.5) and the lowest number of hairy roots (1/1) was obtained from stem segments treated with GM strain at (OD600 = 1). According to the results of the analysis of variance, the effects of double reciprocal of strain in the concentration and strain in the explant was significant at a 1% probability level. Polymerase Chain Reaction (PCR) analysis using the role gene was performed for identification of the transformed hairy roots. In the lines of transgenic hairy roots, a sharp band of 304‑bp was amplified, but no such amplicon was observed in the untransformed root (negative control) sample. The results of this study indicated that the type of bacteria strain, explant type, and bacterial concentration are important factors in hairy roots induction.