Regeneration of plantlets under NaCl stress from NaN3 treated sugarcane explants
In this experiment, mutation induction in explants using NaN3 and subsequently, callus growth and plant regeneration under NaCl stressed conditions was assessed in some sugarcane (Saccharum officinarum L.) cultivars (Thatta-10, CPF-237 and SPHS-19). Immature bases of leaf tips were cultured on MS2n (MS salts, 3.0 mg L-1; 2,4-D, 0.5% NaN3) for 6 days then sub-cultured on MS2 (MS salts, 3.0 mg L-1 2,4-D), MS2a (MS2, 25 mol m-3 NaCl), MS2b (MS2, 50 mol m-3 NaCl) and MS2c (MS2, 75 mol m-3 NaCl) media in dark condition. After 6 weeks, callus growth was observed to be significantly higher (72.34 ± 3.70%) in CPF-237 in the control (MS2), and lowest (57.66 ± 4.34%) in SPHS-19 in MS2d culture. Somatic embryos were induced in proliferated calluses on MS3 (MS salts, 0.5 mg L-1; BAP, 0.4 mg L-1; kin, 0.3 g L-1; casein hydrolysate, 3% sucrose) medium under dark condition for 2 weeks. These calluses were sub-cultured on MS4 (MS, 0.3 mg L-1; BAP, 0.2 mg L-1; kin, 3% glucose), MS4a (MS4, 25 mol m-3 NaCl), MS4b (MS4, 50 mol m-3 NaCl) and MS4c (MS4, 75 mol m-3 NaCl) media. Maximum of 8.41 ± 0.36 plantlets callus-1 were regenerated in MS4 (control) culture of Thatta-10, and 4.94 ± 0.05 plantlets of CPF-237 in 25 mol m-3 NaCl stressed plant regeneration (MS4a) medium. Plant regeneration on MS4b (2.21 ± 0.17 plantlets callus-1) was observed in CPF-237 only. Regenerated plantlets were rooted and considered as salt tolerant in comparison to its parent cultivars.
Key words: Kinetin, somatic embryos, regenerated plantlets, Saccharum officinarum.