Polarity of regeneration in excised leaves of Crassula argentea. I. A role of auxin

Abstract

High concentrations of four auxins, naphthalene acetic acid, indole 3-acetic acid, 2,4-dichlorophenoxyacetic acid, and indole 3-butyric acid, added to leaf segments of Crassula argentea in agar culture eliminate the strong polarity of the regeneration by inducing the formation of distal plantlets. The auxins also changed the normal wound response by inducing the formation of callus on the cut surfaces. All of the auxins increased the numbers of roots formed and inhibited the number of shoots. Unlike cytokinin, which had no effect on the polarity but altered the developmental sequence of regeneration, none of the auxins had any effect on the normal developmental sequence of regeneration, but did affect the morphology of the newly formed roots. There were differential concentration responses for each of the four auxins.