Tumor formation in Nicotiana: Auxin levels and auxin inhibitors in normal and tumor-prone genotypes.

Auxin and auxin-inhibitors from acidic ether extracts of normal stem tissue of Nicotiana longiflora, N. debneyi-tabacum, their tumor producing F 1 hybrid and non-tumor and tumor-prone segregants were separated by thin-layer chromatography and measured by an Avena curvature test. A significantly higher amount of auxin, very likely IAA, was found in the F 1 hybrid and the tumor-prone segregants as compared to the non-tumor tissues. Inhibitory substances appeared at different Rf's but generally in low amounts. One inhibitor seems to be identical with the "inhibitor β". In general, the results indicate that higher levels of auxin are associated with tumor-prone tissues in the F 1 hybrid and the segregants of a later generation carrying an alien longiflora chromosome on a debneyi-tabacum background. The role of this growth-regulating substance as related to tumor formation in Nicotiana is discussed.