Synthesis and Characterization of Nicotiana-Solanum Graft Chimeras

Abstract

Intergeneric Nicotiana tabacum L./Solanum laciniatum Ait. graft chimeras were produced from decapitated grafts made between these two graft compatible species. Graft unions were treated with or without either the auxin, p-chlorophenoxyacetic (p-CPA) or the cytokinin, benzylaminopurine (BAP). While BAP was inhibitory to shoot formation, p-CPA increased the number of adventitious shoots and raised the frequencies of shoot-forming grafts obtained. Approximately 9% (14/151) of the shoots produced at p-CPA-treated graft unions were intergeneric chimeras. The auxin application significantly increased levels of chimeral shoot recovery numbers thus indicating a direct auxin effect on chimeral shoot production. The types and numbers of chimeras produced were independent of the scion/stock graft combination employed. All chimeras appeared to arise initially as mericlinal or sectorial chimeras, with a proportion of the former ones (5/14) stabilizing into periclinal chimeras. The morphological characteristics of these latter chimeras were compared with those of the two parental species. The LII layer of species determined the characteristics of the vegetative and floral components. However, the LI layer modified the qualitative traits of both components. The LIII layer on the other hand altered the quantitative traits of the vegetative organs and the flower. This layer also determined the growth type, breeding behaviour and inflorescence type of synthesized chimeras. These organizational functions of the LIII layer have not been reported previously.