Tissue Distribution of Avenanthramides and Gene Expression of Hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyl Transferase (HHT) in Benzothiadiazole Treated

Oats produce a group of natural products termed avenanthramides. These compounds are produced in both the vegetative tissue and the grain. In leaf tissue they are produced in response to crown rust infection and by chemical plant defense activators and likely other environmental stresses. Grain avenanthramide production tends to be constitutive but concentrations are highly variable and strongly influenced by environmental conditions. In this paper we report the effect of a plant defense activator (benzothiadiazole (BTH)) on the temporal expression and tissue distribution of avenanthramides in the leaf, stem, root, panicle stem, glumes, lemma/palea and filling grain in the oat plant. Hydroxycinnamoyl-CoA: hydroxyanthranilate N-hydroxycinnamoyl transferase (HHT, a member of the BADH acyltransferase family and the final enzyme in the biosynthetic pathway to the avenanthramides) activity is also determined in these tissues as well as the relative expression ratios of HHT mRNA resulting from BTH treatment. Evidence for phloem transport of the avenanthramides is also presented. In summary, following BTH treatment, leaf tissue is the predominate location for avenanthramide biosynthesis. However, significant amounts are also found in the upper and lower stems, roots, panicle stems and glumes. The lemma/palea and filling grain contained demonstrable, but substantially lower amounts of the avenanthramides. Avenanthramides were also detected in the phloem sap, indicating source to sink transport of these metabolites following BTH treatment.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author