Conservation and clade-specific diversification of pathogen-inducible tryptophan and indole glucosinolate metabolism in Arabidopsis thaliana relatives
Article first published online: 21 JUL 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 192, Issue 3, pages 713–726, November 2011
How to Cite
Bednarek, P., Piślewska-Bednarek, M., Ver Loren van Themaat, E., Maddula, R. K., Svatoš, A. and Schulze-Lefert, P. (2011), Conservation and clade-specific diversification of pathogen-inducible tryptophan and indole glucosinolate metabolism in Arabidopsis thaliana relatives. New Phytologist, 192: 713–726. doi: 10.1111/j.1469-8137.2011.03824.x
- Issue published online: 19 OCT 2011
- Article first published online: 21 JUL 2011
- Received: 16 April 2011, Accepted: 8 June 2011
- Arabidopsis thaliana;
- plant immunity;
- tryptophan metabolism
- •A hallmark of the innate immune system of plants is the biosynthesis of low-molecular-weight compounds referred to as secondary metabolites. Tryptophan-derived branch pathways contribute to the capacity for chemical defense against microbes in Arabidopsis thaliana.
- •Here, we investigated phylogenetic patterns of this metabolic pathway in relatives of A. thaliana following inoculation with filamentous fungal pathogens that employ contrasting infection strategies.
- •The study revealed unexpected phylogenetic conservation of the pathogen-induced indole glucosinolate (IG) metabolic pathway, including a metabolic shift of IG biosynthesis to 4-methoxyindol-3-ylmethylglucosinolate and IG metabolization. By contrast, indole-3-carboxylic acid and camalexin biosyntheses are clade-specific innovations within this metabolic framework. A Capsella rubella accession was found to be devoid of any IG metabolites and to lack orthologs of two A. thaliana genes needed for 4-methoxyindol-3-ylmethylglucosinolate biosynthesis or hydrolysis. However, C. rubella was found to retain the capacity to deposit callose after treatment with the bacterial flagellin-derived epitope flg22 and pre-invasive resistance against a nonadapted powdery mildew fungus.
- •We conclude that pathogen-inducible IG metabolism in the Brassicaceae is evolutionarily ancient, while other tryptophan-derived branch pathways represent relatively recent manifestations of a plant–pathogen arms race. Moreover, at least one Brassicaceae lineage appears to have evolved IG-independent defense signaling and/or output pathway(s).