SIMPLE METHOD FOR OVERCOMING THE LETHALITY OBSERVED IN THE HYBRID BETWEEN NICOTIANA-SUAVEOLENS AND NICOTIANA-TABACUM

Hybrid plants between N. suaveolens and N. tabacum exhibit lethality u nder standard culture conditions and die at the cotyledonary stage. Fo r overcoming this type of hybrid lethality, the effect of cytokinin wa s tested. The intact hybrid seedlings were cultured on media containin g cytokinin (0-10mg/l kinetin or 6-benzylaminopurine (BAP)). Adventiti ous buds were regenerated from the base of the hypocotyl or the primar y root of the dying seedlings. The regenerated shoots were transferred to the medium containing 2mg/l 3-indoleacetic acid (IAA) to accelerat e rooting. The hybrid seedlings maintained a vigorous growth without d eveloping any lethal symptoms up to maturity in a greenhouse. Forty ch romosomes were counted in their somatic cells and their morphological characters were intermediate between those of parental species. Intact seedling culture with the addition of cytokinin was found to be a ver y simple method for overcoming lethality in this cross-combination.