Effect of chemical systemic acquired resistance elicitors on avenanthramide biosynthesis in oat (Avena sativa).

Oats produce a group of phenolic antioxidants termed avenanthramides. These metabolites are, among food crops, unique to oats and have shown, in experimental systems, certain desirable nutritional characteristics such as inhibiting atherosclerotic plaque formation and reducing inflammation. Avenanthramides occur in both the leaves and grain of oat. In the leaves they are expressed as phytoalexins in response to crown rust (Puccina coronata) infection. The experiments reported here demonstrate that avenanthramide levels in vegetative tissue can be enhanced by treatment with benzothiadiazole (BTH), an agrochemical formulated to elicit systemic acquired resistance (SAR). The response to BTH was dramatically stronger than those produced with salicylic acid treatment. The roots of BTH treated plants also showed a smaller but distinct increase in avenanthramides. The dynamics of the root avenanthramide increase was substantially slower than that observed in the leaves, suggesting that avenanthramides might be transported from the leaves.