Stilbenoid prenylation pathway discovery in peanut using targeted transcriptomics (Poster)

Abstract

In peanut, Arachis hypogaea, defense responses to biotic and abiotic stresses include the synthesis of prenylated stilbenoids, with over 45 such compounds identified to date. The diversification of secondary metabolites in plants is expanded by prenylation activities, and in recent studies this modification has been shown to enhance biological activities of polyphenolic compounds. We describe our discovery of genes responsible for stilbenoid prenylation* as well as studies underway to understand the regulation of these metabolic programs in peanut. Sequencing RNA from a well-characterized peanut hairy root system, we built a transcriptome reference and correlated transcripts with metabolites produced over a time course of elicitation. Transcripts encoding candidate enzymes were identified and characterized functionally by heterologous transient expression. Prenyltransferases we call AhR4DT-1 and AhR3’DT-1 catalyze distinct reactions, and our studies suggest that these act in the first committed steps that convert non-prenylated into prenylated stilbenoids.

Here we highlight the functional transcriptomics that led to these discoveries, and our ongoing approaches to find other genes that act in the regulation of this defensive metabolic program. Our identification of the first plant stilbenoid-specific prenyltransferases advances the understanding of this specialized gene family, and contributes some of the functional definition that is needed generally to refine the annotations of plant genomes.

*Yang T, Fang L, Sanders S, Jayanthi S, Rajan G, Podicheti R, Kumar TKS, Mockaitis K, Medina-Bolivar F, 2017. JBC, in press. Stilbenoid prenyltransferases define key steps in the diversification of peanut phytoalexins.