Differential responses to salinity stress of two varieties (CoC 671 and Co 86032) of sugarcane (Saccharum Officinarum L.)

Abstract

A comparative study was made to assess salt stress responses of sugarcane (Saccharum officinarum L.) var. CoC 671 and Co 86032 using in vitro plantlets by subjecting them to increasing concentrations of NaCl (0, 50, 100, 150, 200 and 250 mM) and checking relative growth rate (RGR), membrane damage rate (MDR), soluble proteins, osmolytes (proline, glycine betaine), ions (Na⁺ and K⁺) and activity antioxidant enzymes (peroxidase, ascorbate peroxidase, guaiacol peroxidase, catalase and superoxide dismutase). As the concentration of NaCl increased, the RGR was found to decrease by 42.1 and 77.7%, the MDA level increased by 32.5 and 55.8% and proline increase of about 43 and 189% was seen in CoC 671 and Co 86032 respectively. CoC 671 was adapted to a higher Na⁺ concentration (150 mM) than Co 86032. As for the K⁺ accumulation, it displayed similar patterns as in Na⁺ accumulation. In general, it was observed that in all cases except catalase, CoC 671 displayed higher tolerance to NaCl (up to 150 mM) than Co 86032 (up to 100 mM). Based on the results, it is suggested that CoC 671 displayed NaCl tolerance up to about 150 mM, while that of Co 86032 was around 100 mM. The study also indicates that in vitroplantlets can be used for screening salt tolerance in sugarcane.

Keywords: In vitro selection, NaCl salinity stress, relative growth rate (RGR), osmolytes, antioxidant enzymes, sugarcane