Isolation of a NaCl-tolerant mutant of Chrysanthemum morifolium by gamma radiation: in vitro mutagenesis and selection by salt stress

A stable NaCl-tolerant mutant (R1) of Chrysanthemum morifolium Ramat has been developed by in vitro mutagenesis with gamma radiation (5 gray; Gy). Salt tolerance was evaluated by the capacity of the plant to maintain both flower quality and yield under NaCl stress. Enhanced salt tolerance of the R1 mutant was attributed to increased activities of reactive oxygen species (ROS)-scavenging enzymes, namely superoxide dismutase (SOD), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR), and to reduced membrane damage, higher relative water content (RWC), chlorophyll and carotenoids contents. RAPD analysis revealed two polymorphic bands (956 and 1093 bp) for the R1 mutant that might be considered as specific RAPD markers associated with salt tolerance. Better performance of the R1 progeny under identical salinity stress conditions, even in the second year, confirmed the genetic stability of the induced salt tolerance character. The R1 mutant developed by gamma ray treatment can be considered a salt-tolerant mutant showing all the positive characteristics of tolerance to NaCl stress.