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Metabolic and evolutionary costs of herbivory defense: systems biology of glucosinolate synthesis
Author(s) -
Bekaert Michaël,
Edger Patrick P.,
Hudson Corey M.,
Pires J.Chris,
Conant Gavin C.
Publication year - 2012
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2012.04302.x
Subject(s) - glucosinolate , biology , flux balance analysis , flux (metallurgy) , herbivore , arabidopsis thaliana , metabolic network , chemical defense , ecology , biochemistry , botany , chemistry , organic chemistry , gene , mutant , brassica
Summary Here, we describe our updated mathematical model of A rabidopsis thaliana Columbia metabolism, which adds the glucosinolates, an important group of secondary metabolites, to the reactions of primary metabolism. In so doing, we also describe the evolutionary origins of the enzymes involved in glucosinolate synthesis. We use this model to address a long‐standing question in plant evolutionary biology: whether or not apparently defensive compounds such as glucosinolates are metabolically costly to produce. We use flux balance analysis to estimate the flux through every metabolic reaction in the model both when glucosinolates are synthesized and when they are absent. As a result, we can compare the metabolic costs of cell synthesis with and without these compounds, as well as inferring which reactions have their flux altered by glucosinolate synthesis. We find that glucosinolate production can increase photosynthetic requirements by at least 15% and that this cost is specific to the suite of glucosinolates found in A . thaliana , with other combinations of glucosinolates being even more costly. These observations suggest that glucosinolates have evolved, and indeed likely continue to evolve, for herbivory defense, since only this interpretation explains the maintenance of such costly traits.