Efficient somaculture system and exploitation of somaclonal variation for bacterial wilt resistance in tomato

An efficient somaculture system involving somatic callus derived from stem and leaf explants of four tomato varieties viz. BWR 1, BWR 6, PKM I and Culture 340 was evolved. MS basal medium supplemented with 2 mg/litre BAP and 1 mg/litre NAA was found to be the most efficient in generating maximum plantlets, whereas 1/2 MS fortified with 1 mg/litre NAA was found most effective in inducing maximum roots. Substantial somaclonal variations were observed in respect of major agronomic traits viz. plant height, plant spread, number of primary branches, number of fruits and fruit yield per plant at SC₂ generation. This offers ample scope of selection for genetic improvement of this crop. Somaclones were simultaneously screened for bacterial wilt resistance caused by Pseudomonas solanacearum under sick-plot condition. Marked variation in resistance profile was discernible in comparison to parental base population. A few elite lines coupled with bacterial wilt resistance were selected to evolve superior wilt-resistant lines for mass cultivation in the humid tropics of Andamans.