Development of NaCl-tolerant strain in Chrysanthemum morifolium Ramat. through in vitro mutagenesis.
One NaCl-tolerant chrysanthemum (Chrysanthemum morifolium Ramat.) variant (E2) has been developed in a stable form through IN VITRO mutagenesis using ethylmethane sulfonate (EMS) as the chemical mutagen. Salt tolerance was evaluated by the capacity of the plant to maintain both flower quality and yield under stress conditions. Enhanced tolerance of the E2 variant has been attributed to the increased activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), and dehydroascorbate reductase (DHAR), and, to a lesser extent of membrane damage than NaCl-treated control plants. Isoform analysis revealed that an increase in total SOD activity in the E2 variant was solely due to significant activation of the Cu/Zn isoform. Elevated levels of carotenoids and ascorbate in E2 leaves have been reflected in their higher free radical scavenging capacity (RSC) expressed in terms of DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging ability. Data reflect that a proper balance between enzymatic and non-enzymatic defence systems is required for combating salinity stress in chrysanthemum. Better performance of the E2 progeny under same salinity stress condition, even in the second year, confirms the genetic stability of the salt-tolerance character. On the whole, the E2 variant, developed through 0.025 % EMS treatment, might be considered as a NaCl-tolerant strain showing positive characters towards NaCl stress.