256 



1. lODOACETATE AND lODOACETAMIDE 



Table 1-40 

 Effects of Iodoacetate on Growth of Plant Tissues 



pathway seems unlikely as the cause, so that one must assume an action 

 elsewhere. Perhaps this is directly on the plasma membrane, altering per- 

 meability or auxin transport, or there is in some way a sensitization to 

 auxin. If this is so, one must wonder what role this action plays at higher 

 concentrations. 



A relationship between inhibition by iodoacetate and auxin has been 

 emphasized since the earliest work, Howard and McClintock (1940) noting 

 that 3-indoleacetate can somewhat overcome the inhibition. However, most 

 workers have remarked that iodoacetate seems to block rather specifically 

 the growth stimulation induced by 3-indoleacetate (e.g., Christiansen et al., 

 1949), having much less effect on basal growth.* Pohl and Ochs (1953) 

 found the effects of iodoacetate to vary with the concentration of 3-indole- 

 acetate present, although the actions of the auxin on cress roots seem ab- 



* Unfortunately much of the earher work did not include adequate controls, par- 

 ticularly the effects of iodoacetate in the absence of 3-indoleacetate, so that the con- 

 clusions were unjustified. 



