Cross tolerance mechanisms of osmotic and ionic stress adapted cell lines of rice towards salinity

Abstract

Present study investigated the cross tolerance mechanisms of osmotic [25% poly ethylene glycol (PEG)] and ionic (25 mM LiCl) stress tolerant cell lines of rice (Oryza sativa L.) cv. Swat-1. The adapted lines showed tolerance up to six generation on stress free medium. When adapted and un-adapted cell lines were subjected to 200 mM NaCl, there was 98% reduction in relative growth rate (RGR) of un-adapted line and the adapted (PEG and LiCl) cell lines showed significantly higher tolerance. Albeit there were no qualitative differences among adapted and un-adapted cell lines under salt stress. However, responding mechanisms of adapted and un-adapted cell lines to osmotic and ionic homeostasis to tolerate NaCl stress were highly different. PEG adapted cells line appeared to acquire halophytic behavior of a salt accumulator, while LiCl adapted line performed like salt tolerant glycophyte. The tolerance strategies of adapted lines were not confined to the same type of stress but showed cross tolerance towards other abiotic stresses.