INDUCED GENETIC VARIABILITY IN SESAME (Sesamum indicum L): A COMPARATIVE STUDY ON THE MUTAGENIC EFFECTS OF RADIATION AND EMS IN SEED GERMINATION, POLLEN VIABILITY AND CHLOROPHYLL MUTANTS

Abstract

The present study envisaged the effects of two mutagens, gamma rays and EMS on the phenotypes of two sesame varieties viz., TMV7 and SVPR1. A known quantity of dry, uniform, and healthy seeds of TMV7 and SVPR 1 were irradiated using Co60 (Cobalt 60) with different doses (250, 300, 350, 400, 450 Gy) of gamma rays. For chemical mutagenesis, different concentrations of EMS @ 0.20%, 0.40% and 0.60% was used and treated for 8 h. The dose-response curve of the probit analysis showed that the optimal lethal dose for SVPR1was lower than TMV7. The expected LD50 values of gamma radiation for TMV 7 and SVPR1 were 403.91Gy and 343.84Gy, respectively. For EMS, the expected LD50 values are 0.525 % and 0.276% for TMV7 and SVPR1 respectively. Germination and pollen fertility declined linearly with an increase in dose or concentration of the mutagens. Three classes of chlorophyll mutants viz., xantha, chlorine, and viridis in M2 generation reveals a dose dependent relationship between mutagens and frequency of chlorophyll mutants. Mutagenic effectiveness was higher at lower doses whereas mutagenic efficiency was observed higher at extremity doses in both the varieties. The overall considerations on M1 generation effects showed that SVPR1was highly sensitive to gamma rays and TMV7 produced more viable mutationsthan SVPR1. The current studies suggest gamma rays as an efficient mutagen to induce essential mutations in TMV7 for the further crop improvement program.