Isolation and characterization of NaCl-tolerant mutations in two important legumes, Clitoria ternatea L. and Lathyrus sativus L.: Induced mutagenesis and selection by salt stress

Six best performing mutants exhibiting NaCl-tolerance were identified in gamma ray induced M-2 progeny of three different varieties of Clitoria ternatea L. and Lathyrus sativus L. each by preliminary assessment of plant growth under salt stress. Salt tolerance of these six mutants, designated as CR1 and CR2 in C. ternatea and as LR1, LR2, LR3 and LR4 in L. sativus was evaluated by their responses to 22 different morpho-physiological and biochemical parameters under 130 mM NaCl treatment on 15-day-old seedlings. A positive control set (mutant plants-watering only with distilled water) and a negative control (unmutagenised mother variety-treated with 130 mM NaCl) was also maintained. Among the six mutants, LR4 out performed all others showing significantly higher plant biomass production, leaf K+/Na+ ratio and lower level of lipid perodixation and electrolyte leakage as compared to positive control. It was closely followed by CR2, LR3 and LR2 seedlings. Enhanced salt tolerance of these four mutants was attributed to increased activities of reactive oxygen species (ROS)-scavenging enzymes-superoxide dismutase and ascorbate peroxidase along with non-enzymatic ascorbate and carotenoids in leaves. Both CR1 and LR1 manifested moderate level of salt tolerance, but significantly higher than negative control (NC) plants.