UPTAKE AND METABOLISM OF INDOLE-3-BUTYRIC ACID DURING THE IN VITRO ROOTING PHASE IN PEAR CULTIVARS (PYRUS COMMUNIS)

The role of applying indole-3-butyric acid (IBA) in adventitious root formation was examined by analyzing the uptake and subsequent metabolism of IBA in microcuttings of two pear cultivars: Conference (easy-to-root) and Doyennè d’Hiver (difficult-to-root). Rooting was induced by exposing shoots to 1.5 μM IBA and ³H-IBA for 7 days in the dark and then transferring them in the light.
After 4 days of culture the percentage of ³H-IBA taken up by shoots was approximately 40% in Conference and only 19% in Doyennè d’Hiver.
IBA was metabolized very rapidly in both cultivars and 12 hours after application only a small portion of the total extractable radioactivity could be identified as free IBA. About 50% of the IBA taken up was tentatively identified as indole-3-butyrylaspartic acid (IBAsp) in both cultivars.
Only Conference showed the ability to convert IBA into free IAA during the root induction period.
Endogenous level of free IAA rapidly increased in Conference during the first 2 days while it remained very low in Doyennè. It is suggested that part of the differences in rooting ability between the two cultivars could be related to differences in auxin uptake and metabolism.

VII International Symposium on Plant Growth Regulators in Fruit Production

R. Baraldi, G. Bertazza, S. Predieri, A.M. Bregoli, J.D. Cohen

https://doi.org/10.17660/ActaHortic.1993.329.68