Characterisation of morphology and root formation in the model woody perennial shrub Solanum aviculare Forst expressing rolABC genes of Agrobacterium rhizogenes

Transgenic plants of Solanum aviculare Forst. expressing the rolABC genes of Agrobacterium rhizogenes exhibited altered shoot morphologies in comparison to untransformed plants. Altered growth and development characteristics included retarded growth, suppressed apical dominance, shortened internodes; smaller highly lanceolated leaves and smaller, sterile flowers. Pronounced leaf wrinkling was a common feature of the transgenic plants. Shoot slices and leaf fragments of transgenic plants when cultured in vitro exhibited significantly higher root formation capacities than explants derived from non-transformed plants. Explants from transgenic plants were able to produce roots in limited manner without exogenous auxin and presented higher sensitivity to promoting effect of IBA. The suppressing effects of light, kinetin, the inhibitor of putrescine synthesis alpha-difluoromethyl-ornithine and gibberellin (GA(3)) on root formation were significantly lower than in control explants. Vanadate (an inhibitor of phosphatases/kinases) strongly blocked root differentiation in control and in transformant lines. The antigibberellin paclobutrazol increased the numbers of roots in transformant shoot segments and in segments of control plants, whereas the antiauxin p-chlorophenoxyisobutyric acid, the polyamines putrescine and spermidine, the conjugated auxin indoxyl-beta-glucoside and the conjugated cytokinin BAP-9-glucoside had no marked effects on root development. Differences in root formation abilities between transformed lines in response to the different treatments were found. (C) 1997 Elsevier Science Ireland Ltd.