Authors: Mayumi Hachinohe Hiroshi Matsumoto
Publish Date: 2007/09/26
Volume: 33, Issue: 10, Pages: 1919-1926
Abstract
l34Dihydroxyphenylalanine ldopa is one of the few allelochemicals in which the phytotoxic action mechanism has been studied Excess exogenous ldopa suppresses root elongation in some plant species and the inhibitory action is speciesselective The main factor of phytotoxicity of ldopa is considered to be oxidative damage by reactive oxygen species ROS and/or free radical species FRS This study was performed to elucidate the mechanism of speciesselective phytotoxicity The involvement of ROS/FRS and polyphenol oxidase PPO in speciesselective phytotoxicity was examined with barnyardgrass Echinochloa crusgalli L and lettuce Lactuca sativa L tolerant and susceptible species respectively Lipid peroxidation and melanin accumulation correlated with growth inhibition by Ldopa Antioxidants ascorbic acid and αtocopherol decreased lipid peroxidation and melanin accumulation and rescued lettuce root from growth inhibition The oxidation of Ldopa by PPO was much greater in lettuce than in barnyardgrass From these results the phytotoxicity of Ldopa is considered due to the oxidative damage caused by ROS/FRS generated from the melanin synthesis pathway PPO activity might be involved in the mechanism of speciesselective phytotoxicity between barnyardgrass and lettuce
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