Defense metabolites of potato

Hydroxycinnamic acid amides (HCAA) are the major phytoalexins in pathogen-infected potato leaves where they are supposed to act as antimicrobial and as cell wall enforcing compounds. It has recently been recognized that, in contrast to the Solanaceae-specific biosynthetic enzymes, members of the BAHD family are responsible for the synthesis of HCAA in other plants. In Arabidopsis, the gene At5g61160, which encodes an agmatine coumaroyltransferase (AtACT) is activated in response to Alternaria brassicicola infection. We performed a detailed biochemical characterization of AtACT in order to gain insight into the mechanism of acyl transfer and a better understanding of the flexibility of the enzyme and the plasticity of secondary product formation. By introducing At5g61160 into potato plants, novel HCAA are produced, thus enlarging the spectrum of antimicrobial HCAA in potato.