Abstract
Growth and callus formation were observed using pith tissues of Nicotiana tabacum “Bright Yellow” (2n=48) and N. alata (2n=18) which were cultured on a basal medium or basal medium plus IAA, kinetin, or both.
In “Bright Yellow”. chromosome aberrations and the formation of tracheid-like cells were observed in subcultured callus tissues, but no organ formation was found through 7 successive subcultures.
In callus tissue of N. alata, numerous roots were formed when only 2.0mg/l IAA was added to the basal medium. On the medium with 2.0mg/l IAA and 1.0mg/l kinetin, the callus tissues produced many buds but no roots. Callus tissues forming roots were easilly brought into budding by transplanting them onto the medium for bud formation. On the other hand, callus tissues forming buds produced roots when transferred to the basal medium supplemented with yeast extract. From those callus tissues were obtained restored plants (disomic or trisomic), which developed into maturity.
