The Effect of Different Combinations of Plant Growth Regulators in MS medium on Callus Induction and Direct Regeneration of Galega officinalis

This study aimed to evaluate the effect of different types and concentrations of plant growth regulators in MS medium on callus formation and regeneration of different explants of medicinal plant Galega officinalis. To callus induction, leaf, root, hypocotyl, and stem nodes explants were cultured on MS medium containing different concentrations of 2,4-D (0.5, 1, 3, and 5 mg/l) in combination with BAP (0, 0.5, 1 and 3 mg/l) or Kin (0, 0.5, 1, and 3 mg/l). It was observed that 2,4-D in combination with Kin was very effective and in most of the used concentrations, it resulted in 100% callus induction. Among them the 5:0.5 mg/l concentration of 2,4-D:Kin in the nodal stem explant showed the highest callus growth with an average of 1450 mg fresh callus weight. In order to direct regeneration, leaf, cotyledon, and stem nodes were cultured in MS medium containing different concentrations of BAP and Kin in combination with NAA, while regeneration was observed only in the stem nodes. The highest regeneration rate was related to 0.25:0.1 mg/l in both BAP: NAA and Kin:NAA with an average of 93.33%. The highest amount of induced shoots (with an average of 2.86 shoots in each explant) and the highest shoot length (5.6 cm) were observed at 2:0.5 and 2:0.1 mg/l of BAP:NAA, respectively. The shoots obtained from the regeneration experiment were transferred to MS medium containing different levels of NAA and IAA for rooting. The results of mean comparisons showed that 0.25 or 0.5 mg/l of NAA or IAA resulted in the highest percentage of rooting with an average of about 90%. The highest number of roots was related to explants cultured in 0.25 mg/l of both NAA and IAA growth regulators (with an average of 4 roots per explant) and also, the highest root length was observed in explants cultured in 0.25 mg/l of IAA (with an average of 6.5 cm). At all, in this study, the most appropriate combination of plant growth regulators and explant for callus induction and direct regeneration of G. officinalis was introduced, which can be useful in future biotechnological studies of this medicinal plant.