《植物生理学报》 2011, 47(4): 392-398

Cd²⁺胁迫诱导烟草悬浮细胞脯氨酸积累的生化途径及外源脯氨酸对Cd²⁺胁迫下H₂O₂产生的抑制作用

文锦芬^{1, 2, 3}, 杨双龙², 龚明^2,*

1中国农业大学水利与土木工程学院, 北京100083; 2云南师范大学生命科学学院, 教育部生物能源持续开发利用工程研究中心, 云南省生物质能与环境生物技术重点实验室, 昆明650092; 3昆明理工大学现代农业工程学院, 昆明650224

通信作者：龚明；E-mail: gongming63@163.com；Tel: 0871-5516516

摘　要：

Cd2+可提高烟草悬浮细胞脯氨酸的含量, 顺序上调脯氨酸合成关键酶鸟氨酸转氨酶(OAT)、精氨酸酶、D1-吡咯啉-5-羧酸合成酶(P5CS)和谷氨酸脱氢酶(GDH)的活性, 降低脯氨酸降解关键酶脯氨酸脱氢酶(ProDH)的活性, 表明Cd2+胁迫诱导烟草细胞脯氨酸的积累是脯氨酸合成的鸟氨酸途径和谷氨酸途径顺序激活、而脯氨酸降解途径显著抑制的综合结果。此外, Cd2+能导致烟草细胞H2O2的快速产生及H2O2产生相关酶(质膜NADPH氧化酶、细胞壁多胺氧化酶及共价结合与离子结合细胞壁过氧化物酶)活性升高和脂质过氧化产物丙二醛(MDA)增加, 导致烟草细胞的氧化胁迫。外源脯氨酸预处理显著抑制了Cd2+诱导的烟草细胞H2O2的产生与MDA的增加, 减轻了Cd2+诱导的氧化胁迫。而脯氨酸抑制Cd2+诱导的H2O2产生可能是由于脯氨酸抑制了H2O2产生相关酶的活性所致。

关键词：Cd2+; 烟草悬浮细胞; 脯氨酸; 代谢途径; 过氧化氢

收稿：2011-01-10   修定：2011-02-14

资助：国家自然科学基金(30460016)

Biochemical Pathways of Cd²⁺ Stress-Induced Proline Accumulation and Inhibitory Effect of Exogenous Proline on Cd²⁺-Induced H₂O₂ Production in Tobacco (Nicotiana tabacum L.) Suspension Cells

WEN Jin-Fen^1,2,3, YANG Shuang-Long², GONG Ming^2,*

¹College of Water Conservancy & Civil Engineering, China Agricultural University, Beijing 100083, China; ²Key Laboratory of Biomass Energy and Environmental Biotechnology, Yunnan Province; Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education; School of Life Sciences, Yunnan Normal University, Kunming 650092, China; ³College of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650224, China

Corresponding author: GONG Ming; E-mail: gongming63@163.com; Tel: 0871-5516516

Abstract:

Cd²⁺ treatment could lead to a significant accumulation of proline, sequential up-regulation of activities of the key enzymes (ornithine-δ-aminotansferase, arginase, D¹-pyrroline-5-carboxylate synthetase and glutamate dehydrogenase) for proline biosynthesis, and inhibition of activity of the key enzyme proline dehydrogenase for proline degradation in tobacco (Nicotiana tabacum L.) suspension cells. These results indicated that the Cd²⁺ stress-induced proline accumulation in the tobacco cells might be a combined result of the orderly activation of the ornithine pathway and the glutamate pathway of proline biosynthesis, and inhibition of proline degradation pathway. Furthermore, Cd²⁺ stress increased the production of H₂O₂, activities of the H₂O₂ producing-related enzymes (plasma membrane NADPH, cell wall polyamine oxidase, covalently and ionically-bound cell wall peroxidases), the product (MDA) of membrane lipid peroxidation and oxidation stress in the tobacco cells. Exogenous application of proline significantly decreased H₂O₂ production, MDA content and oxidation stress induced by Cd²⁺ stress. The inhibition of H₂O₂ production by exogenous proline might be due to the declined activities of the H₂O₂ producing-related enzymes under Cd²⁺ stress.

Key words: Cd²⁺; tobacco suspension cells; proline; metabolic pathways; H₂O₂