Degousee N., Triantaphylides C., Montillet J. L.
Departement de Physiologie Vegetale et Ecosystemes, Centre d'Etudes de Cadarache, Commissariat a I' Energie Atomique, F-13108 Saint Paul-Lez-Durance, Cedex, France.
Plant Physiol. 1994 Mar;104(3):945-952. doi: 10.1104/pp.104.3.945.
The efficiency of hydroperoxides (tert-butyl hydroperoxide, hydrogen peroxide) and sulfhydryl reagents (iodoacetamide, p-chloromercuribenzene sulfonic acid) as glyceollin elicitors was examined in relation to sulfhydryl oxidation, or alteration, and to lipid peroxidation, in 3-d-old soybean hypocotyl/radicle, Glycine max. These oxidative events were investigated as possible early steps in the transduction mechanisms leading to phytoalexin synthesis. Free protein sulfhydryl groups were not modified after any of the eliciting treatments, thus indicating that immediate massive protein oxidation or modification cannot be considered a signal transduction step. Unlike sulfhydryl reagents, which led to a decrease of the free nonprotein sulfhydryl group (free np-SH) pool under all of the eliciting conditions, the results obtained with hydroperoxides indicated that immediate oxidation of the np-SH is not required for the signal transduction. Moreover, elicitation with 10 mM tertbutyl hydroperoxide did not lead to further oxidation or to changes in np-SH level during the critical phase of phenylalanine ammonialyase activation (the first 20 h), suggesting that np-SH modifications are probably not involved in hydroperoxide-induced elicitation. On the other hand, all treatments leading to significant glyceollin accumulation were able to trigger a rapid (within 2 h) lipid peroxidation process, whereas noneliciting treatments did not. In addition, transition metals, such as Fe2+ and Cu+, were shown to stimulate both hydrogen peroxide-induced lipid peroxidation and glyceollin accumulation, again emphasizing that the two processes are at least closely linked in soybean. Among the oxidative processes triggered by activated oxygen species, oxidation of sulfhydryl compounds, or lipid peroxidation, our results suggest that lipid peroxidation is sufficient to initiate glyceollin accumulation in soybean. This further supports the hypothesis that lipid peroxidation could be involved as a step in the signal cascade that leads to induction of plant defenses.
在3日龄的大豆下胚轴/胚根（Glycine max）中，研究了氢过氧化物（叔丁基氢过氧化物、过氧化氢）和巯基试剂（碘乙酰胺、对氯汞苯磺酸）作为大豆抗毒素诱导剂的效率，涉及巯基氧化或改变以及脂质过氧化。这些氧化事件被作为导致植物抗毒素合成的转导机制中可能的早期步骤进行研究。在任何诱导处理后，游离蛋白质巯基都未被修饰，因此表明立即大量的蛋白质氧化或修饰不能被视为信号转导步骤。与巯基试剂不同，在所有诱导条件下，巯基试剂都会导致游离非蛋白质巯基（游离np-SH）池减少，而过氧化物的结果表明，信号转导不需要np-SH的立即氧化。此外，用10 mM叔丁基氢过氧化物诱导在苯丙氨酸解氨酶激活的关键阶段（最初20小时）并未导致进一步氧化或np-SH水平变化，这表明np-SH修饰可能不参与过氧化物诱导的激发。另一方面，所有导致大豆抗毒素显著积累的处理都能够触发快速（2小时内）的脂质过氧化过程，而非诱导处理则不能。此外，过渡金属，如Fe2+和Cu+，被证明能刺激过氧化氢诱导的脂质过氧化和大豆抗毒素积累，再次强调这两个过程在大豆中至少紧密相连。在由活性氧引发的氧化过程中，巯基化合物的氧化或脂质过氧化，我们的结果表明脂质过氧化足以启动大豆中大豆抗毒素的积累。这进一步支持了脂质过氧化可能作为导致植物防御诱导的信号级联中的一个步骤的假设。
