Effect of plant growth regulators on callogenesis and regeneration of Hyssopus officinalis in In vitro conditions

Hyssopus officinalis, one of the most important medicinal plants belongs to the Lamiaceae family and it is rich in essential oils that is used for medicinal purposes, health care and food. By tissue culture method such as; callus production and plant regeneration, we able to increase the production of quality and quantity of effective secondary metabolites in this medicinal important plant. This study was performed on MS medium, aimed to determine the most appropriate concentration of auxin and cytokinin plant growth regulators to obtain the maximum efficiency in induction and production of callus and in vitro regeneration of plantlets from leaf and hypocotyl explants of Hyssopus officinalis.

Callus induction was evaluated in a factorial experiment based on completely randomized design (CRD) with three replications. In this experiment, different levels of NAA plant growth regulator (0, 0.5, 1 and 2 mg/L) and two different types of explant, leaves and hypocotyl explants were used. Traits including, relative growth rate, fresh and dry weight, diameter, color and physical structure and the percentage of callus induction was measured. Also, the direct and indirect regeneration was evaluated in a factorial experiment based on completely randomized design (CRD) with three replications. The different levels of plant growth regulator (1 and 2 mg/L NAA) and (2 and 4 mg/L BAP) were used and regeneration percentage were measured.

The highest percentage of callus induction (100 %) were obtained on MS medium with 2 mg/L NAA in hypocotyl explants. The highest percentage of direct regeneration (73 %) and indirect regeneration (80 %) were observed in MS medium with combinations of 2 mg/L NAA and 4 mg/L BAP in hypocotyl and calli derived from hypocotyl.

The results showed that the hypocotyl explant was more suitable for callus induction and regeneration in Hyssopus officinalis.