Benz(a)
anthracene induced vegetative buds on callus derived from stem tissue of haploid plants of Nicotiana tabacum, a response similar to that obtained by a combination of kinetin and IAA.
Earlier investigations on tobacco pith callus and stem tissues cultured in vitro have shown that a quantitative balance between 3-indoleaceticacid (IAA) and adenine concentration determines the type of growth and organ formation (Skoog and Tsui, 1948;Miller and Skoog, 1953). Later, with the discovery of kinetin, it was suggested that adenine is acting as a precursor to endogenous cytokinins. Skoog and Miller (1957) demonstrated that interaction between IAA and kinetin can exert decisive influence on the induction of roots and shoots on the callus of Nicotiana tabacum (cv. "Wisconsin 38"). Similar control of differentiation of roots and vegetative buds in tobacco pith callus depending upon the ratio of IAA and cytokinins has also been demonstrated for 6-benzylaminopurine, 1-benzyladenine, 6-(y, y-dimethy]allylamino)-purine (Hamzi and Skoog, 1964); and 6-(3,3-dimethylallyl)adenosine (see Srivastava, 1967). Schaeffer and Smith (1963) have observed that stem callus of N. suaveolens grown on kinetin-free medium produced roots whereas it showed pronounced shoot development but no root formation when grown on the medium containing kinetin. Very little growth took place on a medium without IAA and kinetin.
In the present investigation we have observed that benz(a)anthracene (BaA), a tobacco-smoke carcinogen (see Wynder and Hoffmann, 1967), replaced the morphogenetic effect of IAA and kinetin on the callus derived from the stem tissue of haploid tobacco plants. However, it proved ineffective on the callus from the cultivar "Wisconsin 38 ".