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

Pea (Pisum sativum L. cv. Alaska) root tips were incubated innutrient medium for 24 h prior to herbicide treatment. Endogenouslevels of putrescine, cadaverine, spermidine and spermine weredetermined in root tip sections at various times following 10and 20µM napropamide application. Little effect on polyaminelevels occurred within 12 h of treatment. However, by 48 h oftreatment, putrescine levels increased more than 3-fold in eachof the root sections within 4 mM of the tip while cadaverineincreased by 2-fold in only the root section 4 to 10 mM fromthe tip. After 72 h of herbicide treatment, the level of putrescineincreased over 8-fold within 5 mM of the root tip. Napropamidehad little effect on spermidine and spermine concentration within10 mM of the root tip after 72 h of exposure. This representsthe first report of an herbicideinduced accumulation of putrescineand cadaverine and suggests a possible phytotoxic effect ofhigh concentrations of putrescine on roots. (Received December 8, 1987; Accepted September 20, 1988)