Salicylic acid-induced accumulation of glucosinolates in oilseed rape (Brassica napus L.) leaves

Applying a salicylic acid soil drench to oilseed rape plants increased the concentration of glucosinolates in their leaves. The intensity of this ‘induction’ depended on the concentration of salicylic acid applied and the age of the leaf: developing leaves retained enhanced levels of glucosinolates longer than mature leaves. 2-Phenylethylglucosinolate showed the greatest increase in concentration, with only minor increases in other glucosinolates in developing leaves. This response to salicylic acid is more specific than that observed following fungal infection or damage by herbivores. The results presented here are among the first to demonstrate an increase in secondary metabolite content in response to salicylic acid. The implications of this response are discussed in terms of the role of salicylic acid and glucosinolates in plant defence.