The acute effect of copper on the levels of indole-3-acetic acid and lignin in peanut roots

Abstract

Cu-treated peanut (Arachis hypogaea L.) seedlings showeda significant inhibition in peanut root growth, and a decrease in endogenousindole-3-acetic acid (IAA) content. The decline of IAA content in Cu-treatedtissue was accompanied by an increase in the activity of cationic peroxidase(POD) isozyme P8.5, which was correlated with an increase in cationic PODtranscripts. Cu might suppress the growth of peanut roots by inducing thesynthesis of the cationic POD isozyme that degrades endogenous IAA. Theincrease in the activity of anionic POD isozyme P3.5 was correlated with therise in lignin content in Cu-treated roots. We suggest that the increase inanionic POD isozyme P3.5 induced by Cu might be responsible for ligninsynthesis in peanut roots, and may also remove excess hydrogen peroxide causedby Cu, thus playing a detoxifying role during Cu treatment.