Potential role of cytokinin–auxin synergism, antioxidant enzymes activities and appraisal of genetic stability in Dianthus caryophyllus L.—an important cut flower crop

The regeneration potential, antioxidative enzyme activities, and genetic stability among micropropagated plantlets of Dianthus caryophyllus L. were evaluated. Multiple adventitious shoots were induced from leaf explants on Murashige and Skoog medium incorporated with various combinations and concentrations of plant growth regulators (PGRs). The highest leaf explant response (90%), number of shoots per explant (15.30 ± 1.19), and shoot length (6.75 ± 0.63 cm) was recorded in response to a combination of 2.5 μM 6-benzyladenine and 0.5 μM α-naphthaleneacetic acid (NAA) after 8 wks culture. Subsequent subculturing for five passages, on a medium with the same composition of PGRs, induced the highest shoot number (42.50 ± 1.44), with an average shoot length of 8.06 cm after the fourth subculture. Different concentrations of indole-3-butyric acid (IBA) were tested to determine the optimum conditions for ex vitro rooting of microshoots. The best result was accomplished with a pulse treatment of IBA (100 μM) applied to the basal end of the microshoot for 30 min, followed by transfer to plastic cups containing soilrite, and eventually established in natural soil with an 85% survival rate. The determination of activities of antioxidative enzymes (superoxide dismutase, ascorbate peroxidase, catalase, and glutathione reductase) revealed involvement of these enzymes in shoot differentiation and development. All of these activities were interlinked with each other and played significant roles in the scavenging of toxic free radicals. Intersimple sequence repeat DNA analysis was carried out using five primers. The amplification products were monomorphic in micropropagated plants, similar to those of the mother plant. No polymorphisms were detected revealing the genetic integrity of the micropropagated plants.