Regulon-guided discovery of defensive secondary metabolism in Arabidopsis
B. BARCO (1), N. Clay (1) (1) Department of MCDB, Yale University, U.S.A.

Plant secondary metabolites are crucial in defending plant hosts against microbial pathogens, and secondary metabolite biosynthetic genes represent a significant portion of the plant genome. Arabidopsis thaliana is a model for plant secondary metabolism, with many of its major inducible and constitutively expressed compounds derived from tryptophan. As most enzymes involved in eukaryotic secondary metabolite biosynthesis are not physically clustered, we previously applied transcriptomics approaches to uncover a novel class of tryptophan-derived compounds involved in defense. To further increase our efficacy in these methods, we utilized the regulon-guided organization common to many secondary metabolic pathways to identify additional secondary biosynthetic pathways contributing to the Arabidopsis immune response. Here, we show that a transcription factor subfamily activates biosynthetic genes and metabolites from known and unknown pathways. In addition, we show that these transcription factors are crucial for invoking defense against the bacterial hemibiotroph Pseudomonas syringae pv. tomato DC3000. These findings show that the Arabidopsis chemical defense response consists of a relatively small number of transcription factors which coordinate a large suite of biosynthetic enzymes and are responsible for essential defensive processes. This transcription factor-based approach lends itself to pathway discovery across stages of development or for other conditions for which there is no known elicitor.

Abstract Number: P16-440
Session Type: Poster