Gil-Monreal Miriam, Zabalza Ana, Missihoun Tagnon D, Dörmann Peter, Bartels Dorothea, Royuela Mercedes
Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain.
Institute of Molecular Physiology and Biotechnology of Plants (IMBIO), University of Bonn, D-53115 Bonn, Germany.
Plant Sci. 2017 Nov;264:16-28. doi: 10.1016/j.plantsci.2017.08.003. Epub 2017 Aug 17.
Imazamox and glyphosate represent two classes of herbicides that inhibit the activity of acetohydroxyacid synthase in the branched-chain amino acid biosynthesis pathway and the activity of 5-enolpyruvylshikimate-3-phosphate synthase in the aromatic amino acid biosynthesis pathway, respectively. However, it is still unclear how imazamox and glyphosate lead to plant death. Both herbicides inhibit amino-acid biosynthesis and were found to induce ethanol fermentation in plants, but an Arabidopsis mutant deficient in alcohol dehydrogenase 1 was neither more susceptible nor more resistant than the wild-type to the herbicides. In this study, we investigated the effects of the amino acid biosynthesis inhibitors, imazamox and glyphosate, on the pyruvate dehydrogenase bypass reaction and fatty acid metabolism in A. thaliana. We found that the pyruvate dehydrogenase bypass was upregulated following the treatment by the two herbicides. Our results suggest that the Arabidopsis aldehyde dehydrogenase 7B4 gene might be participating in the pyruvate dehydrogenase bypass reaction. We evaluated the potential role of the aldehyde dehydrogenase 7B4 upon herbicide treatment in the plant defence mechanism. Plants that overexpressed the ALDH7B4 gene accumulated less soluble sugars, starch, and fatty acids and grew better than the wild-type after herbicide treatment. We discuss how the upregulation of the ALDH7B4 alleviates the effects of the herbicides, potentially through the detoxification of the metabolites produced in the pyruvate dehydrogenase bypass.
甲氧咪草烟和草甘膦分别代表两类除草剂，它们分别抑制支链氨基酸生物合成途径中乙酰羟酸合酶的活性以及芳香族氨基酸生物合成途径中5-烯醇丙酮酸莽草酸-3-磷酸合酶的活性。然而，甲氧咪草烟和草甘膦如何导致植物死亡仍不清楚。这两种除草剂均抑制氨基酸生物合成，并被发现能诱导植物进行乙醇发酵，但缺乏乙醇脱氢酶1的拟南芥突变体对除草剂的敏感性和抗性均不比野生型更强。在本研究中，我们调查了氨基酸生物合成抑制剂甲氧咪草烟和草甘膦对拟南芥丙酮酸脱氢酶支路反应和脂肪酸代谢的影响。我们发现，用这两种除草剂处理后，丙酮酸脱氢酶支路被上调。我们的结果表明，拟南芥醛脱氢酶7B4基因可能参与丙酮酸脱氢酶支路反应。我们评估了除草剂处理时醛脱氢酶7B4在植物防御机制中的潜在作用。过表达ALDH7B4基因的植物积累的可溶性糖、淀粉和脂肪酸较少，并且在除草剂处理后比野生型生长得更好。我们讨论了ALDH7B4的上调如何减轻除草剂的影响，这可能是通过丙酮酸脱氢酶支路中产生的代谢产物的解毒作用实现的。
