Authors:

Chase Hearn

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About Paper:

Phenylpropanoids are specialized metabolites derived from the amino acid phenylalanine and include lignin, as well as the natural sunscreen sinapoylmalate. In addition to phenylpropanoids, plants in the order Brassicales also produce specialized metabolites known as indole glucosinolates from the amino acid tryptophan, which have a role in defense against herbivory and pathogen infection. In the Arabidopsis thaliana reduced epidermal fluorescence5 (ref5-1) mutant, sinapoylmalate fails to accumulate due to the accumulation of an indole glucosinolate aldoxime precursor (IAOx), resulting in a phenotype characterized by elongated hypocotyls and decreased UV-induced fluorescence. In Arabidopsis thaliana, glucosinolate-phenylpropanoid crosstalk is facilitated by the Mediator complex (MED5) which limits phenylpropanoid levels by increasing expression of a group of Kelch Domain F-Box genes (KFBs) in response to levels of IAOx. These KFBs participate in the degradation of phenylalanine ammonia-lyase (PAL) which is required to catalyze the first step of phenylpropanoid metabolism. Here, we set out to identify as-yet-unidentified genes involved in phenylpropanoid-glucosinolate crosstalk by performing a ref5-1 mutant suppressor screen. We characterized ten candidate ref5-1 suppressors by analyzing levels of sinapoylmalate, hypocotyl length, KFB expression, PAL activity, and lignin content. We plan to use ref5-1 suppressors with expected phenotypes to discover new mechanisms by which members of the Brassicaceae and their allies coordinate the production of indole glucosinolates and phenylpropanoids.

Source:

Purdue University / 2023

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Co-authors:

Chase Hearn