Comparison of auxin activty in tumourous and normal callus cultures from sunflower and tobacco plants

In normal and tumourous calluses of sunflower and tobacco the level of extractable auxins was determined by <i>Avena coleoptile</i> straight growth test. Auxin activity was detected practically in two zones: I - at position with R_f 0.2-0.4 and II - at position with R_f 0.6-0.9. The tumour tissues of sunflower and tobacco plants, representing different types of neoplastic growth exhibit a 3 times higher auxin activity as compared with that of the corresponding normal tissues. Tobacco tissues, on the other hand, had a higher auxin level than the corresponding sunflower tissues and they exhibited different proportions in the activity of zones I and II, which points to a dominance of genetic regulation of hormone metabolism in these plants.