Gamma Irradiation of Embryogenic Callus Cultures and In vitro Selection for Salt Tolerance in Sugarcane (Saccharum officinarum L.)

Radiation induced mutagenesis followed by in vitro selection was employed for salt tolerance in popular Indian sugarcane (Saccharum officinarum L.) cv. CoC-671. Embryogenic calli were gamma irradiated and exposed to different levels of NaCl (42.8,85.6,128.3,171.1,213.9,256.7,299.5,or 342.2 mM). The relative growth rate (RGR) decreased progressively with increasing salt stress and was the least with a salt stress of 256.7 mM (0.25 ± 0.009),almost 10 fold lesser than the control. The RGR was significantly lower in 85.6 mM and higher salt stressed calli than the control. The survival percent also decreased,with an increase in NaCl concentration. In case of 10 and 20 Gy irradiated calli,regeneration was observed up to 85.6 mM NaCl selection,medium,whereas,higher treatments (128.3 mM and beyond) exhibited browning initially. However,in the subsequent subcultures,regeneration was obtained in the case of 10 and 20 Gy irradiated calli on 128.3 and 171.1 mM NaCl selections. Higher dose of gamma irradiation (40 Gy) also showed regeneration,but only with 85.6 mM NaCl selection. The unirradiated calli regenerated the highest number of plantlets followed by 10 and 20 Gy irradiated calli on salt selection. A total of 147 plantlets were selected from different salt levels. The salt selected plants are being tested for their field performance.