外源 GSH 对 NaCl 胁迫下番茄幼苗叶片及根系离子微域分布的影响

周艳; 刘慧英; 崔金霞; 张健伟

doi:10.11674/zwyf.16311

外源 GSH 对 NaCl 胁迫下番茄幼苗叶片及根系离子微域分布的影响

Effects of exogenous glutathione on ions micro-distribution in leaf and root of tomato seedlings under NaCl stress

摘要

摘要:
目的盐胁迫是限制新疆番茄生长的重要障碍因子之一，而外源喷施谷胱甘肽 (GSH) 是解决这一问题的有效措施。探讨外源 GSH 缓解番茄盐胁迫的效应和作用机制，可为该措施的有效应用提供理论依据。
方法采用营养液栽培法，选用番茄品种‘中蔬四号’为试材。在营养液中加入 NaCl 100 mg/L，使其产生盐胁迫，以不加 NaCl 作为对照 (CK)，试验处理包括不喷施 GSH (NaCl)、喷施 GSH (+ GSH)、喷施 GSH 合成酶抑制剂 (+ BSO) 以及喷施 GSH 和 BSO (+ BSO + GSH)。测定番茄幼苗叶片和根系中与耐盐性相关的 K⁺、Ca²⁺、Mg²⁺、Na⁺ 和 Cl^– 的离子微域分布状态和平衡。
结果NaCl 胁迫下番茄叶片和根系所有组织细胞中 Na⁺ 和 Cl^– 相对含量显著提高，K⁺ 相对含量和 K⁺/Na⁺、Ca²⁺/Na⁺、K⁺/Cl^– 比值降低，说明 NaCl 胁迫使细胞中 Na⁺ 和 Cl^– 有害离子积累及胞内离子稳态严重破坏；外源 BSO 施用进一步加剧了 NaCl 胁迫下番茄叶片和根系细胞的 K⁺/Na⁺ 失衡。而外源 GSH 施用抑制了 NaCl 胁迫下番茄叶片和根系对 Na⁺ 的吸收，降低了 Cl^– 的相对含量，提高了 K⁺/Na⁺、Ca²⁺/Na⁺、K⁺/Cl^– 比值。外源 GSH 亦使 NaCl+BSO 胁迫下番茄叶片各组织及根系中皮层、内皮层和中柱的 Na⁺ 未检出，根系和叶片各组织中 Cl^– 相对含量显著降低，K⁺ 和 Ca²⁺ 相对含量及 K⁺/Na⁺、Ca²⁺/Na⁺、K⁺/Cl^–、Ca²⁺/Cl^– 比值显著提高。
结论外源 GSH 通过抑制盐胁迫下番茄叶片和根系对 Na⁺ 的吸收，降低 Cl^– 吸收，改善细胞中离子的微域分布和维持离子平衡, 从而缓解了盐胁迫对番茄的毒害作用，提高了番茄的耐盐性。

Abstract:
ObjectivesNaCl stress is one of the major obstacles during tomato growth in Xinjiang, and glutathione (GSH) spray has been considered as an effective solution. Exploring the effect and mechanism of exogenous GSH on alleviating salt stress in tomato will provide theoretical basis for the efficient use of GSH.
MethodsA hydroponic experiment was conducted and tomato (Solanum lycopersicum L.) cv. Zhongshu No. 4 was used as experimental material. 100 mg/L NaCl was added into the nutrition solution to form NaCl stress growth condition. The solution without NaCl was used as control (CK), and the main treatments included no glutathione spraying (NaCl), GSH spraying (+ GSH), glutathione synthesis inhibitor spraying (+ BSO) and both GSH+BSO spraying (+ BSO + GSH). The ion micro-distribution status and balance of K⁺, Ca²⁺, Mg²⁺, Na⁺ and Cl^– in leaf and root of tomato seedlings were measured.
ResultsUnder NaCl stress condition, both Na⁺ and Cl^– contents were increased significantly, and the K⁺ content and the ratios of K⁺/Na⁺, Ca²⁺/Na⁺ and K⁺/Cl^– were decreased in all the cells of leaf and root of tomato seedlings. It indicated that NaCl stress caused the plant accumulation of harmful ions Na⁺ and Cl^– and the serious damage of intracellular ions steady status in the cells of leaf and root of tomato seedlings. The application of exogenous BSO further intensified the off-balance of the ratio of K⁺/Na⁺ in leaf and root of tomato seedlings under NaCl stress. While the application of exogenous GSH inhibited the absorption of Na⁺ and significantly decreased the relative content of Cl^– and increased the ratios of K⁺/Na⁺, Ca²⁺/Na⁺ and K⁺/Cl^– in leaf and root of tomato seedlings under NaCl stress. Under salt stress with BSO treatments, the application of exogenous GSH also greatly inhibited the absorption of Na⁺ and resulted in the relative content of Na⁺ in cells of all tissues of leaf and in mediopellis, endodermis and stele of tomato root was below the detection limit. Under salt stress with BSO treatments, the application of exogenous GSH significantly decreased the relative content of Cl^– and increased the relative content of K⁺ and Ca²⁺ and the ratios of K⁺/Na⁺,Ca²⁺/Na⁺, K⁺/Cl^– and Ca²⁺/Cl^– in leaf and root of tomato seedlings.
ConclusionsGSH could alleviate the toxicity from salt ions and enhanced salt tolerance in tomato seedlings by inhibiting the absorption of Na⁺, decreasing the absorption of toxic ions and optimizing ions micro-distribution and maintaining ion balance in cells of leaf and root of tomato seedlings under salt stress.

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