Mahmud Jubayer Al, Hasanuzzaman Mirza, Nahar Kamrun, Rahman Anisur, Hossain Md Shahadat, Fujita Masayuki
Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa, 761-0795, Japan.
Department of Agroforestry and Environmental Science, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207, Bangladesh.
Ecotoxicology. 2017 Jul;26(5):675-690. doi: 10.1007/s10646-017-1800-9. Epub 2017 Apr 13.
Chromium (Cr) toxicity is hazardous to the seed germination, growth, and development of plants. γ-aminobutyric acid (GABA) is a non-protein amino acid and is involved in stress tolerance in plants. To investigate the effects of GABA in alleviating Cr toxicity, we treated eight-d-old mustard (Brassica juncea L.) seedlings with Cr (0.15 and 0.3 mM KCrO, 5 days) alone and in combination with GABA (125 µM) in a semi-hydroponic medium. The roots and shoots of the seedlings accumulated Cr in a dose-dependent manner, which led to an increase in oxidative damage [lipid peroxidation; hydrogen peroxide (HO) content; superoxide (O) generation; lipoxygenase (LOX) activity], methylglyoxal (MG) content, and disrupted antioxidant defense and glyoxalase systems. Chromium stress also reduced growth, leaf relative water content (RWC), and chlorophyll (chl) content but increased phytochelatin (PC) and proline (Pro) content. Furthermore, supplementing the Cr-treated seedlings with GABA reduced Cr uptake and upregulated the non-enzymatic antioxidants (ascorbate, AsA; glutathione, GSH) and the activities of the enzymatic antioxidants including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II), and finally reduced oxidative damage. Adding GABA also increased leaf RWC and chl content, decreased Pro and PC content, and restored plant growth. These findings shed light on the effect of GABA in improving the physiological mechanisms of mustard seedlings in response to Cr stress.
铬（Cr）毒性对植物的种子萌发、生长和发育具有危害。γ-氨基丁酸（GABA）是一种非蛋白质氨基酸，参与植物的胁迫耐受性。为了研究GABA在缓解Cr毒性方面的作用，我们在半水培培养基中，单独用Cr（0.15和0.3 mM KCrO，处理5天）以及与GABA（125 µM）联合处理8日龄芥菜（Brassica juncea L.）幼苗。幼苗的根和地上部分以剂量依赖的方式积累Cr，这导致氧化损伤增加[脂质过氧化；过氧化氢（H₂O₂）含量；超氧阴离子（O₂⁻）生成；脂氧合酶（LOX）活性]、甲基乙二醛（MG）含量升高，并破坏抗氧化防御和乙二醛酶系统。铬胁迫还降低了生长、叶片相对含水量（RWC）和叶绿素（chl）含量，但增加了植物螯合肽（PC）和脯氨酸（Pro）含量。此外，给经Cr处理的幼苗补充GABA可减少Cr吸收，并上调非酶抗氧化剂（抗坏血酸，AsA；谷胱甘肽，GSH）以及包括抗坏血酸过氧化物酶（APX）单脱氢抗坏血酸还原酶（MDHAR）、脱氢抗坏血酸还原酶（DHAR）、谷胱甘肽还原酶（GR）、谷胱甘肽过氧化物酶（GPX）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、乙二醛酶I（Gly I）和乙二醛酶II（Gly II）在内的酶抗氧化剂的活性，最终减少氧化损伤。添加GABA还增加了叶片RWC和chl含量，降低了Pro和PC含量，并恢复了植物生长。这些发现揭示了GABA在改善芥菜幼苗应对Cr胁迫的生理机制方面的作用。
