Regeneration, establishment and evaluation of somaclones in Sorghum bicolor (L.) Moench

Novel in vitro techniques have the potential to aid conventional breeding programs. Somaclonal variation is considered to be a useful source of variation and has been demonstrated to be feasible in crop species like wheat, rice and maize. A study was taken up at Tissue Culture Laboratory, University of Agricultural Sciences Dharwad, India, for callus induction, maintenance and regeneration of two well established sorghum varieties, M35-1 and A-1 to study somaclonal variation for both qualitative and quantitative characters. The frequency of callus induction was 90 and 83.3 percent in M35-1 and A-1, respectively, on MS medium with 2 mg l-l of 2,4-D. On higher levels of sucrose (60 gl-l), M35-1 showed good response for both regeneration and rooting, while for variety A-1 BA(0.5 mg l-l) and NAA (0.2 mg l-l) had to be supplemented for satisfactory levels of regeneration (73.3%) and rooting respectively. The regenerated plants (SC₁) were selfed to obtain the seeds for the next generation. In M35-1, variations were observed for chlorophyll, phyllotaxy and midrib structure, while male sterile and branched phenotypes occurred in A-1 families. Combined analysis of variances showed that there was significant difference between and within families for most of the quantitative characters in both cultivars except for the character, fourth leaf breadth in the cultivar A-1. The variation, accompanied by a positive shift from the mean is an indication of the response to selection for any specific character. Occurrence of productive variants among the somaclones of established cultivars like M35-1 and A-1 indicates the possibility of their improvement through somaclonal variation. This revised version was published online in July 2006 with corrections to the Cover Date.