OsPAL as a key salicylic acid synthetic component is a critical factor involved in mediation of isoproturon degradation in a paddy crop

Abstract The chemical isoproturon is widely used for weeding to improve grain productivity in agriculture. Due to its environmental persistence and intensive usage, there is a rising concern regarding isoproturon contamination in food crops that is threatening human health through food chains. This work investigated isoproturon degradation which was affected by salicylic acid, a natural growth regulator in rice plants. Analyses with a salicylic acid synthesis mutant line Ospal (phenylalanine ammonia lyase) showed significantly higher isoproturon accumulation than its wild-type, while spraying exogenous salicylic acid can reverse the phenotype, suggesting that salicylic acid is required to resist isoproturon phytotoxicity and for lower accumulation. This result was well confirmed by three homologue mutants of Arabidopsis which also lost salicylic acid synthetic functions. Profiling genomic loci of isoproturon-exposed wild-type/Ospal rice identified many genes (>2 fold change, p