Novel organized growth and somatic variation of Nicotiana bonariensis protoplast-derived colonies: Transmission to regenerated plants

Mesophyll protoplasts isolated from leaves of axenic shoot cultures of Nicotiana bonariensis underwent sustained cell division and concomitant novel cellular organizational patterns when cultured in liquid Murashige and Skoog medium (1962) containing 2.0 mg 1^?1 naphthaleneacetic acid (NAA), 0.5 mg 1^?1 6-benzylaminopurine (BA) and 9% mannitol. The novel patterns were leaf-like and embryo-like structures which resumed unorganized callus growth prior to shoot regeneration. In addition, the presence or absence of anthocyanin and of chlorophyll pigmentation in the protoplast-derived colonies was also observed. The variation in either presence or absence of anthocyanin in protoplast-derived colonies is restored as anthocyanin synthesis in the regenerated plants. However, the variation for chlorophyll pigmentation observed at the colony stage was transmitted as differences in morphology in the regenerated plants. The mode of shoot regeneration of N. bonariensis protoplasts and the potential value of somatic variants are discussed.