Radiation-induced in vitro mutagenesis system for salt tolerance and other agronomic characters in sugarcane (Saccharum officinarum L.)

Gamma ray-induced in vitro mutagenesis and selection for salt (NaCl) tolerance were investigated in sugarcane (Saccharum officinarum L.). Embryogenic callus cultures were irradiated (10 to 80 Gy) and subjected to in vitro selection by exposure of irradiated callus to NaCl (0, 50, 100, 150, 200, and 250 mmol L⁻¹). Increasing NaCl concentrations resulted in growth reduction and increased membrane damage. Salt-selected callus lines were characterized by the accumulation of proline, glycine betaine, and Na⁺ and K⁺ concentration. Higher accumulation of proline and glycine betaine was observed in NaCl stressed callus irradiated at 20 Gy. Na⁺ concentration increased and K⁺ concentration decreased with increasing salt level. Irradiated callus showed 50–60% regeneration under NaCl stress, and in vitro-regenerated plants were acclimatized in the greenhouse, with 80–85% survival. A total of 138 irradiated and salt-selected selections were grown to maturity and their agronomic performance was evaluated under normal and saline conditions. Of these, 18 mutant clones were characterized for different agro-morphological characters and some of the mutant clones exhibited improved sugar yield with increased Brix%, number of millable canes, and yield. The result suggest that radiation-induced mutagenesis offers an effective way to enhance genetic variation in sugarcane.