The plant allelochemical coumarin effectively inhibits the germination of Brassica parachinensis (B. parachinensis) seeds. Quantification of endogenous phytohormones showed that contents of abscisic acid (ABA), ABA glucose ester, gibberellin A20 (GA20), GA3, GA15, GA24, GA9 and GA4 were higher in germinating seeds than in seedlings. Moreover, the presence of coumarin significantly reduced the content of bioactive GA4 which is thought to positively regulate seed germination. Histochemical staining and spectrophotometry of reactive oxygen species (ROS) revealed that exogenous GA3 and GA4+7 could effectively promote the production of endogenous ROS during germination and that the GA synthesis inhibitor paclobutrazol could effectively inhibit production of ROS. Coumarin significantly inhibited the accumulation of ROS, especially superoxide anion radical (${\rm O}_2^{{\cdot}{-}} $). This inhibitory effect could be restored by the addition of exogenous GA3 and GA4+7. Coumarin also inhibited the activity of the ROS-degrading enzymes such as superoxide dismutase, catalase and peroxidase as well as β-amylase in seeds and seedlings. Taken together, we propose a model for the regulation of seed germination in B. parachinensis by coumarin, Gas and ROS, in which coumarin may delay seed germination by reducing endogenous GA4, thus decreasing the accumulation of ROS.

中文翻译：

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香豆素延迟 Brassica parachinensis 种子萌发涉及减少 GA4 的产生和随之而来的 ROS 积累的减少

植物化感香豆素有效抑制植物的萌发甘蓝(B. parachinensis) 种子。内源性植物激素定量显示脱落酸（ABA）、ABA葡萄糖酯、赤霉素A20（GA20), 遗传算法3, 遗传算法15, 遗传算法24, 遗传算法9和遗传算法4种子发芽率高于幼苗。此外，香豆素的存在显着降低了生物活性GA的含量4这被认为可以正向调节种子发芽。活性氧 (ROS) 的组织化学染色和分光光度法显示，外源性 GA3和遗传算法4+7能有效促进发芽过程中内源性ROS的产生，GA合成抑制剂多效唑能有效抑制ROS的产生。香豆素显着抑制活性氧的积累，尤其是超氧阴离子自由基。${\rm O}_2^{{\cdot}{-}} $）。这种抑制作用可以通过添加外源 GA 来恢复3和遗传算法4+7. 香豆素还抑制种子和幼苗中 ROS 降解酶（如超氧化物歧化酶、过氧化氢酶和过氧化物酶）以及 β-淀粉酶的活性。总之，我们提出了一个调控种子萌发的模型B. parachinensis通过香豆素、Gas 和 ROS，其中香豆素可以通过减少内源性 GA 来延缓种子发芽4，从而减少 ROS 的积累。