College of Horticulture, Henan Agricultural University, Zhengzhou 450002, PR China.
College of Horticulture, Henan Agricultural University, Zhengzhou 450002, PR China.
Ecotoxicol Environ Saf. 2021 Jul 1;217:112254. doi: 10.1016/j.ecoenv.2021.112254. Epub 2021 Apr 24.
Phenanthrene (PHE), a typical organic pollutant, has drawn attention in recent years due to its toxicity to plants and human health. Gamma-aminobutyric acid (GABA) induce plant tolerance to diverse stresses. However, the role and regulatory mechanisms of GABA in PHE stress responses in plants remains largely uncharacterized. Here, we showed that GABA content increased by 44.5%, 89.2%, 160% and 39.2% under 50, 100, 200 and 300 µM PHE treatment, respectively compared with mock. GABA treatment alleviated PHE-induced growth inhibition in a dose-dependent manner, with the most effective concentration of 50 mM GABA. Although exogenous GABA could not influence the accumulation of PHE in cucumber, it significantly mitigated photosynthetic inhibition and enhanced the transcripts and activities of the antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), resulting in less accumulation of hydrogen peroxide (HO) and superoxide (O). Importantly, timecourse analyses of glutathione (GSH) homeostasis showed that GABA markedly increased GSH content and GR activity as well as the transcripts of GSH biosynthesis-related genes GSH1, GSH2 and GR during PHE stress. Conversely, pretreatment with GSH biosynthesis inhibitor buthionine sulfoximine (BSO) abolished the GABA-induced changes in PHE stress. Together, these results suggest that GABA enhances tolerance to PHE stress via a GSH-dependent system of antioxidant defense in cucumber.
菲（PHE）是一种典型的有机污染物，近年来由于其对植物和人类健康的毒性而引起了关注。γ-氨基丁酸（GABA）诱导植物耐受多种胁迫。然而，GABA 在植物 PHE 胁迫反应中的作用和调节机制在很大程度上仍未被阐明。在这里，我们发现与对照相比，50、100、200 和 300 μM PHE 处理下 GABA 含量分别增加了 44.5%、89.2%、160%和 39.2%。GABA 处理以剂量依赖的方式缓解了 PHE 诱导的生长抑制，最有效的浓度为 50 mM GABA。尽管外源性 GABA 不能影响黄瓜中 PHE 的积累，但它显著减轻了光合作用抑制作用，并增强了抗氧化酶如抗坏血酸过氧化物酶（APX）、过氧化氢酶（CAT）、过氧化物酶（POD）和超氧化物歧化酶（SOD）的转录物和活性，导致过氧化氢（HO）和超氧阴离子（O）的积累减少。重要的是，谷胱甘肽（GSH）动态平衡的时程分析表明，GABA 显著增加了 GSH 含量和 GR 活性以及 GSH 生物合成相关基因 GSH1、GSH2 和 GR 的转录物，在 PHE 胁迫期间。相反，GSH 生物合成抑制剂丁硫氨酸亚砜（BSO）预处理消除了 GABA 诱导的 PHE 胁迫变化。综上所述，这些结果表明 GABA 通过黄瓜抗氧化防御的 GSH 依赖系统增强了对 PHE 胁迫的耐受性。
