The effect of 6-Benzyladenine on adventitious shoot formation by Lycopersicon species in vitro.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

Lycopersicon esculentum Mill. cv. Rodade was developed in South Africa for the fresh produce market. This cultivar is also of major importance for South African tomato breeding programmes because of its resistance to bacterial wilt. In this study, aspects of the effects of 6-benzyladenine on adventitious shoot formation by both L. esculentum cv. Rodade and Lycopersicon peruvianum Mill. were studied in vitro. These included the regeneration of adventitious shoots, the effects of different incubation times, the uptake and metabolism of BA and the effect of auxin on the metabolism of BA in both leaf and callus tissue of the two species. Adventitious buds could be regenerated on all tissue types except for callus tissue of L. esculentum. A stepwise increase in the percentage shoots produced was observed indicating a period of induction wherein incubation on a medium containing BA is beneficial to the production of shoots. Leaf tissue was more responsive to BA treatments than callus tissue of both species. The main route of BA metabolism in both species is from BA to [9R]BA and [9R-MP]BA. Callus tissue of L. esculentum cv. Rodade however converted BA to the 3- and 9- glucosides of BA rather than to metabolically active forms of the cytokinin. The auxin, indole-3-acetic acid, played a definite role in the conversion of BA to [3G]BA and [9G]BA in leaf tissue of the tomato cultivar tested, but had no effect in callus tissue of this species.