Experimentally Synthesized Plant Chimeras 2. A Comparison of In vitro and In vivo Techniques for the Production of Interspecific Nicotiana Chimeras*

Abstract

In vitro and in vivo techniques were compared for synthesizing chimeras between Nicotiana glauca Grahm and N tabacum L Interspecific chimeral callus, produced from mixed callus cultures in vitro, was placed on media which favoured only N tabacum shoot formation None of the 474 regenerated N tabacum shoots incorporated N glauca cells into their meristems When chimeral callus was regenerated under hormonal conditions favouring simultaneous organogenesis, of 397 shoots, only non-chimeral shoots of both species arose In vivo, reciprocal splice grafts between species were decapitated just above the graft union and treated with or without auxin—lanolin pastes Auxin increased callus formation but inhibited adventitious shoot formation Three of 209 adventitious shoots arising from the graft union were interspecific mericlinal chimeras which were later stabilized as periclinal chimeras All three chimeras formed when N glauca was the understock Two of the chimeras arose on untreated shoots which produced no visible callus, indicating that excessive callus formation may be unnecessary for multiple cell origin of adventitious shoots to occur