78 Fawcett, Wain, and Wightman 



valeric acid as an intermediate product. Further proof of the pres- 

 ence of one or more of these active acids in each extract was obtained 

 from the bioassay of separate chromatograms of each extract, the re- 

 suhs of which are presented in Figure 2. 



Ahhough, on the basis of (3-oxidation, the propionic, valeric, and 

 heptanoic acids wovdd be expected to yield indole-3-carboxylic acid 

 as end-product, no evidence was obtained in these experiments for 

 the production of this acid during the 48-hr. treatment period em- 

 ployed. During this time interval, however, the valeric and heptanoic 

 acids were readily converted in both wheat and pea tissues to the 

 propionic homologue (Figure 1) , and this fact must be considered in 

 relation to the high growth-regulating activity shown by these com- 

 pounds (Table 2). When duplicate chromatograms containing ex- 

 tracts of the wheat or pea-treated propionic acid were sprayed with 

 Ehrlich's reagent and examined by the wheat cylinder bioassay tech- 

 nique, substantial quantities of this acid were found to be present 

 in each extract and only one zone of high growth-promoting activity 

 was revealed, which coincided exactly with the region of the chroma- 

 togram containing the unchanged propionic acid. These results 

 clearly indicate that the side-chain of (3-(indole-3-)propionic acid is 

 not readily degiaded in wheat or pea tissue and that this molecule, like 

 that of indole-3-acetic acid, can show growth-regulating activity per se. 



On chromatograms from extracts of both wheat and pea-treated 

 propionic, valeric, and heptanoic acids a greenish-orange spot (Rf 

 0.25) developed with Ehrlich's reagent immediately above the posi- 

 tion of the propionic acid (Rf 0.35). The identity of this compound 

 is under investigation. It is inactive in the wheat cylinder, pea seg- 

 ment, and pea curvature tests and, although its color reaction with 

 Ehrlich's reagent and R^ in butanol-ammonia-water suggest that it is 

 (3-(indole-3-)acrylic acid, this has not been confirmed in further work. 



In pea metabolism experiments, the pattern of metabolites on the 

 chromatogram (Figure 1) as revealed by the Ehrlich's reagent is simi- 

 lar to that obtained with extracts from wheat-treated solutions. There 

 is, however, one important difference, this being the appearance on 

 chromatograms from pea-treated solutions of distinct blue spots ^vitll 

 low Rf values. These substances are closely similar in Rf and color 

 reaction to those reported for indolc-3-acctylasj)artic and indole-3-pro- 

 pionylaspartic acids which Andrcae and Good (1,2) have shown to 

 occur in pea metabolism experiments with indole-3-acetic and indole- 

 3-propionic acids. Moreover, Fang et al. (3) have also recently con- 

 firmed by means of a tracer technique that the major metabolic prod- 

 uct obtained in pea tissue from exogenously supplied indole-3-acetic 

 acid-l-C^-* is indole-3-acetylaspartic acid, it is very probable, there- 



