Efficacy of Rhizobium Rhizogenesstrains on Hairy Root Transformation in Stevia Rebaudiana L. Bertoni

Two strains of R. rhizogenes, ATCC15834 and MTCC 532 were tested for their virulence on different explants of Stevia rebaudiana. In case of R. rhizogenes strain ATCC 15834, out of different co-culture period, best results were observed after 48h treatment with maximum mean percentage of root induction on shoot tips (91.66%) as well as maximum mean number of hairy roots (20.6). In case of strain MTCC 532, 3h co-culture period was found to be best with maximum mean percentage of root induction (94.33%) and maximum mean number of hairy root (24.33). The overall study revealed that R. rhizogenes strain MTCC 532 was more effective than ATCC 15834 in terms of hairy root induction in S. rebaudiana. However, both the strains of R. rhizogenes (15834 and 532) were able to produce hairy roots in S. rebaudiana, where strain MTCC 532 was found better in terms of transformation frequency (94.33 %) as well as number of roots per explants (24.33).