Efficient callus induction, plant regeneration and their selection at different NaCl levels in wheat crosses

The experiment encompasses the in vitro culture of immature embryo of nine F1 hybrids including two salt tolerant cultivars Kharchia 375 and Kharchia 65, which were used as female parents. Initially all embryos were cultured on MS medium supplemented with 2, 4-D (5.0 mg/l) for callus formation. Proliferation of the callus on MS medium was fortified with 2, 4-D (3.0 mg/l). The callusing percentage among different crosses varied from 86.85-97.20%. These calli were placed on callus selection medium with graded concentrations of NaCl (4, 12, 20, 28 and 36 dS/m) and a gradual decrease in relative growth of calli under NaCl salinity (1068.80- 29.39) was observed. The different crosses reflected significant difference in the terms of their relative growth and dry weight of calli. The best cross among the various crosses for determination of relative growth (631.98) was between Kh 375 x HD 2009 and for dry weight (21.8 mg/g) between Kh 375 x WH 147. The regeneration potential of non-selected and selected cell lines was assessed on MS medium fortified with 1.0 mg/l BAP and 0.2 mg/l IAA. The shoot regeneration of cell lines selected on various concentrations of NaCl (4, 8, 12, 20 and 28 dS/m) was obtained. The per cent calli forming shoots were decreased with increasing NaCl concentrations of all the tested crosses. However, whole plant regeneration was recorded from untreated calli of all the hybrids. Total 147 spikes obtained from various crosses provided a wide genetic base showing variations for spike length, spikelet number and grain number per spike. Hence, the investigation seems to be relevant for production of somaclones and will prove a beneficial research for development of salt tolerant genotypes in wheat in future.