PAPER CHROMATOGRAPHY OF AUXINS AND INHIBITORS IN TWO NICOTIANA SPECIES AND THEIR HYBRID

Abstract

Auxins and auxin inhibitors from tissue extracts of normal Nicotiana plants, Nicotiana glauca, N. langsdorffii and their hybrid (which spontaneously produces tumors) were separated by ascending paper chromatography with n‐butanol‐distilled water. An Avena curvature test was used for demonstrating growth‐promoting and growth‐inhibiting substances. IAA could be found in extracts of the parents and the hybrid (RF 0.75). Hybrid tissue yielded the highest amount (37.1°), N. glauca tissue less (30.8°), and N. langsdorffii tissue the least amount (8.5°) of IAA. A second growth promoter (RF 0.35) could be separated from the tissue extracts of the parents and the hybrid, but it showed only low activity in the Avena test. Three inhibitors were present in extracts from N. langsdorffii and the hybrid at RF 0.25, 0.45, and 0.85, whereas N. glauca showed only two of them (RF 0.25 and 0.85). The inhibitor with an RF of 0.45 seemed to be identical with the acidic, benzene‐insoluble “inhibitor β” of Bennet‐Clark and Kefford (1953). The inhibitor (neutral, benzene‐soluble) at RF 0.85 could be found in some tissue extracts of the parents and the hybrid, but showed only little activity in the curvature tests. From neutral and from acidic plant extracts within a pH range of 4.4 to 5.8 a third inhibitor with an RF of 0.25 could be separated. It seems that the high concentration of natural IAA in the hybrid is regulated by a variety of inhibitors with different specificities in the growth‐regulating process. Nicotiana langsdorffii tissue has much less auxin but the same variety of inhibitors as the hybrid, whereas N. glauca tissue contains less auxin than the hybrid and only two of the three inhibitors found in N. langsdorffii and hybrid extracts.