Metabolic and evolutionary costs of herbivory defense: systems biology of glucosinolate synthesis
Metabolic and evolutionary costs of herbivory defense: systems biology of glucosinolate synthesis
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DOI：
10.1111/j.1469-8137.2012.04302.x
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发表时间：
2012-10-01
期刊：
影响因子：
9.4
通讯作者：
Conant, Gavin C.
中科院分区：
文献类型：
--
作者：
Bekaert, Michael;Edger, Patrick P.;Conant, Gavin C.
在此，我们描述了我们更新的拟南芥哥伦比亚代谢的数学模型，该模型将重要的次生代谢物组——芥子油苷添加到初级代谢反应中。通过这样做，我们还描述了参与芥子油苷合成的酶的进化起源。我们利用这个模型来解决植物进化生物学中一个长期存在的问题：像芥子油苷这样明显具有防御性的化合物在代谢上是否生产成本高昂。我们使用通量平衡分析来估计在合成芥子油苷和不存在芥子油苷时模型中每个代谢反应的通量。因此，我们可以比较有和没有这些化合物时细胞合成的代谢成本，以及推断哪些反应的通量因芥子油苷合成而改变。我们发现芥子油苷的产生可使光合需求至少增加15%，并且这种成本是拟南芥中所发现的芥子油苷组合所特有的，其他芥子油苷组合成本甚至更高。这些观察结果表明，芥子油苷是为了抵御草食动物而进化的，并且实际上可能还在继续进化，因为只有这种解释才能说明如此高成本的性状得以维持的原因。
Here, we describe our updated mathematical model of Arabidopsis 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.