Salicylate activity. 1. Protection of plants from paraquat injury.
Paraquat (1,1'-dimethyl-4,4'-bipyridinium; methylviologen) is a widely used, nonselective contact herbicide that rapidly stimulates free radical generation. It has been found that the addition of sodium salicylate (sodium 2-hydroxybenzoate; NaSA) to paraquat spray solutions significantly decreased herbicidal activity. This protection was observed in tobacco (Nicotiana tabacum) regardless of whether NaSA was foliar-applied along with or prior to paraquat application or NaSA was soil-applied prior to paraquat application. Because salicylic acid (SA) is an inducer of systemic acquired resistance (SAR) to plant disease, paraquat protection by three SAR inducers (acibenzolar-S-methyl, harpin, and probenazole) and selected salicylate derivatives was assessed. Twenty-two of 24 compounds tested decreased herbicidal activity when foliar-applied with paraquat. Protection from paraquat was greatest with 5-chlorosalicylate, and no protection was observed with benzoic acid. NaSA decreased paraquat activity on npr1-2, an Arabidopsis mutant that is compromised in NaSA-induced SAR, and on ein2-1, an ethylene-insensitive Arabidopsis mutant. Thus, salicylate protection from paraquat is independent of disease resistance and ethylene perception. This suggests the existence of an NaSA-mediated pathway capable of protecting plants from reactive oxygen stress.
Silverman
F Paul
FP
Valent BioSciences Corporation, Long Grove, Illinois 60047, USA. paul.silverman@valnet.com
Petracek
Peter D
PD
Fledderman
Christina M
CM
Ju
Zhiguo
Z
Heiman
Daniel F
DF
Warrior
Prem
P
D017360:Arabidopsis / Q000187:drug effects; D005030:Ethylenes; D018384:Oxidative Stress / Q000187:drug effects; D010269:Paraquat / Q000494:pharmacology*; D010944:Plants / Q000187:drug effects*; D012980:Sodium Salicylate / Q000008:administration & dosage*; D012996:Solutions; D014026:Nicotiana / Q000187:drug effects
D005030:Ethylenes; D012996:Solutions; C036216:ethylene; D010269:Paraquat; D012980:Sodium Salicylate