Mutagenesis and selection in vitro for salinity tolerance and molecular characterization in sugarcane

can greatly facilitate the selection and isolation of useful tolerant lines. In the present study, in vitro mutagenesis was employed in the selection of salt tolerant lines in popular sugarcane (Saccharum officinarum L.) cv. CoC-671. Embryogenic cultures were gamma irradiated (10-50 Gy) and challenged with different levels of NaCl (42.8 - 256.7 mM). Salt stressed calli exhibited lower relative growth rate, decreased cell viability and higher levels of free proline and glycine betaine. The membrane stability (electrolyte leakage) was 3-fold more under salt stress compared to control. The ion levels were drastically affected under salt stress as leached out Na⁺ and K⁺ was much more than that of retained in tissue in both adapted and unadapted callus cultures. The tolerance could also be related to the maintenance of an ample water status and a high to low level of K⁺ to Na⁺ under salinity stress indicating that sugarcane can be a Na⁺ excluder. Plant regeneration was observed in 10 and 20 Gy irradiated calli up to 171.1 mM NaCl selection. A total of 147 plantlets were selected on different salt levels and the tolerant lines are being evaluated at field level. Molecular characterization using RAPD markers revealed genetic polymorphism among selected putative salt tolerant lines and control plants. The proper evaluation of these variants for salinity tolerance may be useful for economic cultivation under the stress regime. (author)