Genetic analysis of somaclonal variation among callus-derived plants of tomato

Genetic stability in tissue-cultured tomato plants was examined by randomly amplified polymorphic DNA (RAPD) analysis. Picloram was used for the first time as alternative auxin, along with benzyladenine (BA) for callus induct ion in tomato, Calli were induced from leaf explants on Murashige and Skoog 's (MS) medium supplemented with 8.88 muM BA and 4.13 muM picloram, Regener ation was obtained after culturing freshly-induced calli on MS medium conta ining 17.7 muM BA alone, Microshoots were rooted in the presence of 10 mu M indole-butyric acid (IBA) on MS medium. DNA samples from the mother plant a nd 11 randomly selected regenerated plants, obtained from a single callus, were subjected to RAPD analysis for the detection of putative somaclones. S ix arbitrary decamer primers produced polymorphic amplification products. I n this set of experiments, fifteen non-parental bands were observed, of whi ch three were shared and twelve unique. The estimation of genetic similarit y coefficient based on RAPD band-sharing data indicated that ten regenerate d plants were more than 95 % similar to the mother plant, except one, LS5, which was found to be distinctly different. This report demonstrates the fe asibility of easy induction of regenerative calli by using combination of p icloram and BA and the possibility of detecting genetic variation through R APD analysis among callus-regenerated plants in tomato at an early stage of growth.