Kinetic studies of certain anti-gibberellins

Abstract

A number of chemical compounds which have the specific effect of retarding stem elongation have been described in recent years (11, 13, 15). Compounds of several rather distinct chemical classes have been found which give the same general growth responses with various plant species. These compounds include 2-chloroethyl trimethyl ammonium chloride (CCC), 2,4-dichlorobenzyl-tributylphosphonium c h 1 o r i d e (Phosfon-D), allyl trimethylammonium bromide (AMAB), and 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine-carboxylate methyl chloride (AMO-1618). The most striking symptoms shown as a result of treatment with these compounds are a marked decrease in stem and petiole elongation. These compounds exert relatively little influence on leaf expansion or root development except at high doses. The marked specificity of action of these compounds on stems and petioles n-ot only suggests immediate practical applications but interesting physiological questions as well. Many authors have noted that responses to these growth inhibitors tend to be just the opposite of responses to gibberellin (1, 16). Apparent interactions between gibberellin and certain of these growth inhibitors have been observed in bean internode growth (3), Ulothrix growth (2), cell division in Chrysanthemum (12), etc. The present work was undertaken to establish definitely whether a functional (i.e. competitive) interaction relationship existed between gibberellin and typical growth retarders or whether gibberellin and these growth retarders act independently, although in opposite directions. An outline of the kinetic basis of these interpretations is presented in the Discussion. Further characteristics of the physiology of action of these materials are also described.