Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran.
Department of Plant, Cell and Molecular Biology, University of Tabriz, Tabriz, Iran.
J Plant Res. 2023 Jan;136(1):117-137. doi: 10.1007/s10265-022-01424-6. Epub 2022 Nov 21.
Tolerance mechanisms employed by plants under environmental stresses can protect them against other co-occurring stresses. In this study, the effect of pre-exposure and simultaneous salt treatment on nickel (Ni) toxicity tolerance in one halophyte (L. sativum) and one glycophyte (L. latifolium) Lepidium species in hydroponics was investigated. In order to compare the species independent from their salt and Ni tolerance level, the glycophyte was subjected to lower salt and Ni concentrations and for a shorter period of time than the halophyte. Salt (NaCl) was applied at 50 and 100 mM concentrations and Ni was provided at an equal free Ni activity by adding 100 and 200 µM Ni as single stresses, but 130 and 300 µM Ni for the treatment of its combination with salt in the glycophyte and halophyte, respectively. Temporal analyses of signaling molecules revealed that the halophyte is characteristically different from the glycophyte in that it exhibits a higher constitutive level of nitric oxide and hydrogen peroxide, a longer duration of response to Ni, and its augmentation by salt. In addition to higher biomass and less Ni accumulation in salt-treated plants, the concentrations of free thiol groups, leaf pigments, proline, free and cell wall-bound phenolics contents, and the activity of phenolic metabolizing enzymes were higher in L. latifolium under the combined salt and Ni treatments than under the single Ni stress. In contrast, the biomass and most biochemical parameters of Ni-stressed L. sativum plants were not enhanced by salt treatment but rather decreased. Our findings shed light on cross-tolerance mechanisms in halophytes and uncovered halophyte survival strategies under multiple stresses.
植物在环境胁迫下采用的耐受机制可以保护它们免受其他共存胁迫的影响。在这项研究中，研究了在水培条件下，盐预处理和同时盐处理对一种盐生植物（L. sativum）和一种甜土植物（L. latifolium）荠属物种对镍（Ni）毒性耐受的影响。为了比较与盐和 Ni 耐受水平无关的物种，将甜土植物置于比盐生植物更低的盐和 Ni 浓度和更短的时间内。盐（NaCl）以 50 和 100 mM 的浓度施加，Ni 通过添加 100 和 200 µM Ni 作为单一胁迫提供相同的游离 Ni 活性，但对于其与盐的组合处理，分别在甜土植物和盐生植物中提供 130 和 300 µM Ni。信号分子的时间分析表明，盐生植物与甜土植物明显不同，盐生植物表现出较高的一氧化氮和过氧化氢的组成水平，对 Ni 的反应持续时间较长，并且盐增强了这种反应。除了在盐处理的植物中具有更高的生物量和较少的 Ni 积累外，游离巯基基团、叶片色素、脯氨酸、游离和细胞壁结合酚类物质的浓度以及酚类代谢酶的活性在 L. latifolium 中更高在盐和 Ni 联合处理下，而不是在单一 Ni 胁迫下。相比之下，盐处理并未增强 Ni 胁迫下 L. sativum 植物的生物量和大多数生化参数，反而降低了。我们的研究结果揭示了盐生植物中的交叉耐受机制，并揭示了盐生植物在多种胁迫下的生存策略。
