Influence of Amino Triazole on the Chloroplast Pigments of Wheat Seedlings

Abstract

3-AMINO-1,2,4-TRIAZOLE is a chemical which has several effects on higher plants. It is a growth inhibitor, and has been used on cotton plants as a defoliant¹. Hall et al. demonstrated that tissues formed subsequent to application of this chemical have a decreased chlorophyll content, while the chlorophyll-level of already mature tissues is unaffected. It was not entirely clear to these investigators whether the observed effect of amino triazole on chlorophyll content is due to chlorophyll destruction or to interference with chlorophyll synthesis. The structural similarity of the triazole ring to the pyrrole rings of chlorophyll prompted the suggestion that amino triazole brings about a block in chlorophyll synthesis prior to the protochlorophyll stage by a competitive inhibitory mechanism¹. This concept was somewhat strengthened when it was found that levels of catalase, which has a similar structure, were also decreased in both plants and animals by treatment with amino triazole^2,3.