Auxin and cytokinin levels in selected and temperature-induced morphologically distinct tissue lines of tobacco crown gall tumors

Two morphologically distinct tissue culture lines were selected from a tobacco (Nicotiana tabacum L. ‘Wisconsin 38’) crown gall tumor: (1) a green teratomous line producing numerous abnormal shoots, designated leafy; and (2) a white, hard, spherical tissue, designated white. These were originally isolated at 27°C, but temperature changes were also found to control these morphologies, with 33°C favoring the development of the leafy form and 21°C favoring the white form. The higher temperature was also correlated with a decrease in the endogenous levels of both auxin and cytokinin, whereas the lower temperature was correlated with an increase in the levels of these growth regulators. There was no significant difference, however, in the auxin and cytokinin levels in the two forms maintained at 27°C, suggesting that the basis for morphological changes at this temperature resides either in very subtle differences in auxin and cytokinin or in factors other than these two growth regulators.