Acclimatization of drought tolerance with Somaclonal variants of sugarcane (Saccharum officinarum L.)

Background: Sugarcane is basically a water loving crop and scarcity of water is not only affecting its overall production but its total sugar contents as well. Somaclonal variation is an intriguing phenomenon to study various genetic and cellular mechanism under in vitro conditions. The induction of somaclonal variation generates useful variability without sexual reproduction in sugarcane. Methods: CPF-248, a drought sensitive variety was used to induce stress tolerance using somaclonal variation approach. Various combinations of callogenesis and regeneration media were used to induce soma clonal variations. The plants, thus achieved, were subjected to drought selection pressure using different concentrations of PEG, the selected plants were referred as in vitro selected putative somaclonal variants 1 & 2 (IPSV1 & IPSV2). These two plants were then subjected to acclimatize under greenhouse conditions by planting them in soil filled plastic pots. The in vitro grown seedlings named as in vitro selected putative somaclonal variants along with parent plants were subjected to drought conditions by withholding watering for 8 days. After 10 days of treatment, data for photosynthetic and biochemical attributes were recorded and subjected to comparison. The activity of antioxidants enzymes like superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), ascorbate and carotenoid contents was analyzed using standard protocols. Results: A significant increase in chlorophyll a, b and carotenoid contents were recorded in IPSV1 and IPSV2 compared to parent genotype. Antioxidant enzymes (SOD, APX, CAT, POD) also increased significantly in somaclonal variants and displayed tolerance under drought condition. Moreover, osmotic adjustment was observed in the form of higher rate of total free amino acid and proline contents in both somaclonal variants. Conclusion: The finding suggests that sugarcane (CPF-248) somaclones generated through tissue culture approach are found to be drought tolerant with improved photosynthesis and antioxidant response. Further, somaclonal variant IPSV1, exhibited better response than other variant (IPSV2).