Herbicide-Induced Diamine Accumulation in Pea Roots. The Effect of Napropamide on Polyamine Levels

Pea (Pisum sativum L. cv. Alaska) root tips were incubated in nutrient medium for 24 h prior to herbicide treatment. Endogenous levels of putrescine, cadaverine, spermidine and spermine were determined in root tip sections at various times following 10 and 20μM napropamide application. Little effect on polyamine levels occurred within 12 h of treatment. However, by 48 h of treatment, putrescine levels increased more than 3-fold in each of the root sections within 4 mM of the tip while cadaverine increased by 2-fold in only the root section 4 to 10 mM from the tip. After 72 h of herbicide treatment, the level of putrescine increased over 8-fold within 5 mM of the root tip. Napropamide had little effect on spermidine and spermine concentration within 10 mM of the root tip after 72 h of exposure. This represents the first report of an herbicideinduced accumulation of putrescine and cadaverine and suggests a possible phytotoxic effect of high concentrations of putrescine on roots.