Effect of Temperature on the Morphology and Cytokinin Levels of Tobacco Crown Gall Teratoma Tissues

Abstract

Summary The cytokinin contents of cultured tobacco crown gall teratoma tissue are reduced when the temperature is raised from 27° C to 34°C. Also, the growth pattern is altered at 34°C in that the tumor shoots express increased elongation and apical dominance, and, in one teratoma line, root formation occurs. When 34°C-cultured tumor shoots are grafted to normal stock plants, the tumor shoots resume a normal growth pattern. The alteration of growth patterns at 34°C can be prevented by supplying the tissues with exogenous cytokinin. Additionally, normal cultured tobacco tissues supplied with high amounts of cytokinin exhibit the morphological characteristics of teratomas. These results indicate that the decrease in cytokinin levels is responsible for the morphological changes at elevated temperature and support the view (Wullens et al., Cell, 24 (1981) 719) that at standard culture temperatures the high cytokinin content of teratomas is responsible for the lack of apical dominance and rooting in tumor shoots.