Sugar Tech (2009) 11(3) : 246-251 RESEARCH ARTICLE An in vitro radiation induced mutagenesis-selection system for salinity tolerance in sugarcane Vikas Yadav Patade · Penna Suprasanna Received: 20 June, 2009; Accepted: 17 August, 2009 1 3 Abstract In vitro radiation induced mutagenesis-selection was employed for salt tolerance in popular Indian sugarcane cv. Co 86032. Radiosensitivity characterized in terms of growth rate and cell viability indicated 20 Gy as LD 50 for embryogenic sugarcane callus cultures. Response of embryogenic calli exposed to different NaCl concentrations (85.6, 128.3, 171.1, 213.9 or 256.7 mM) indicated significant progressive decrease in cell viability and increase in membrane damage rate with increasing salt concentration. Based on these results, 20 Gy irradiated calli were stressed with 85.6 or 171.1 mM NaCl for selection for salt tolerance. Both irradiated or non-irradiated calli exhibited reduced growth rate compared to their respective controls, however, the extent of growth rate reduction was more in un-irradiated stressed calli. Further, in order to study the effect of auxin on salt selection, the calli were cultured on NaCl selection medium supplemented with or without auxin (2, 4-D). The growth rate was higher when NaCl media was supplemented with the auxin than that of without auxin. The calli exposed to 171.1 mM NaCl accumulated more proline than the control and 85.6 mM NaCl stressed irradiated or non- irradiated calli. Proline accumulation in the calli exposed to 85.6 mM NaCl without 2, 4-D was significantly higher than that of the calli stressed at the same salt concentration with 2, 4-D. The irradiated calli stressed with 85.6 mM NaCl medium with or without 2, 4-D accumulated more proline than the non- irradiated calli exposed to the respective salt treatments. Thus, the results suggest in vitro mutagenesis-selection as a powerful tool for enhanced tolerance to abiotic stresses, which may improve the competitiveness of the popular sugarcane cultivars and their commercial cultivation in saline areas. Keywords Sugarcane, in vitro mutagenesis, selection, salt tolerance Introduction Salinity, mainly contributed by NaCl, is one of the important abiotic stress factors and, the principal cause of crop failure worldwide, lowering the average production and productivity of the most crops by more than 50% (Katerji et al., 2001). Salinity affects approximately 20 % of the world’s arable land and approximately 40 % of the irrigated lands (Flowers and Yeo, 1995). Salinity interferes with plant growth as it leads to physiological drought and ion toxicity leading to metabolic toxicity, membrane disorganization, and generation of reactive oxygen species-ROS (Hasegawa et al., 2000). The visible primary effect of salt stress is a decrease in growth rate may be due to the osmotic effect of salt, which affects the early growth phase, or due to ionic effect, which influences growth much later and has a less deleterious effect than osmotic stress, especially at low to moderate salt stress. To achieve salt tolerance, stress induced damage to biological macromolecules must be prevented or alleviated, homeostatic conditions must be reestablished in the new, stressful environment and, growth must resume, albeit at a reduced rate (Munns and Tester, 2008). Sugarcane is an important agro-industrial sugar crop of the world cultivated in more than 20 million hectares. Being a typical glycophyte, salinity in root zone of sugarcane decreases sucrose yield, through its effect on both biomass and juice Vikas Yadav Patade · Penna Suprasanna () Functional Plant Biology Section, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 India email: prasanna@barc.gov.in