López-Orenes Antonio, Martínez-Pérez Ascensión, Calderón Antonio A, Ferrer María A
Department of Agricultural Science and Technology, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain.
Department of Agricultural Science and Technology, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain.
Plant Physiol Biochem. 2014 Nov;84:57-66. doi: 10.1016/j.plaphy.2014.09.003. Epub 2014 Sep 10.
Zygophyllum fabago is a promising species for restoring heavy metal (HM) polluted soils, although the mechanisms involved in HM tolerance in this non-model plant remain largely unknown. This paper analyses the extent to which redox-active compounds and enzymatic antioxidants in roots, stems and leaves are responsible for Pb tolerance in a metallicolous ecotype of Z. fabago and the possible influence of salicylic acid (SA) pretreatment (24 h, 0.5 mM SA) in the response to Pb stress. SA pretreatment reduced both the accumulation of Pb in roots and even more so the concentration of Pb in aerial parts of the plants, although a similar drop in the content of chlorophylls and in the maximum quantum yield of photosystem II was observed in both Pb- and SA-Pb-treated plants. Pb increased the endogenous free SA levels in all organs and this response was enhanced in root tissues upon SA pretreatment. Generally, Pb induced a reduction in catalase, ascorbate peroxidase and glutathione reductase specific activities, whereas dehydroascorbate reductase was increased in all organs of control plants. SA pretreatment enhanced the Pb-induced H2O2 accumulation in roots by up-regulating Fe-superoxide dismutase isoenzymes. Under Pb stress, the GSH redox ratio remained highly reduced in all organs while the ascorbic acid redox ratio dropped in leaf tissues where a rise in lipid peroxidation products and electrolyte leakage was observed. Finally, an organ-dependent accumulation of proline and β-carboline alkaloids was found, suggesting these nitrogen-redox-active compounds could play a role in the adaptation strategies of this species to Pb stress.
豆科霸王是一种修复重金属污染土壤的有前景的物种，尽管这种非模式植物对重金属的耐受机制仍 largely 未知。本文分析了豆科霸王一种金属适应生态型的根、茎和叶中的氧化还原活性化合物和酶促抗氧化剂对铅耐受的贡献程度，以及水杨酸（SA）预处理（24 小时，0.5 mM SA）对铅胁迫响应的可能影响。SA 预处理降低了根中铅的积累，更显著地降低了地上部分植物中的铅浓度，尽管在铅处理和 SA-铅处理的植物中都观察到叶绿素含量和光系统 II 最大量子产量有类似下降。铅增加了所有器官中内源性游离 SA 的水平，并且在 SA 预处理后，根组织中的这种反应增强。一般来说，铅导致过氧化氢酶、抗坏血酸过氧化物酶和谷胱甘肽还原酶的比活性降低，而脱氢抗坏血酸还原酶在对照植物的所有器官中增加。SA 预处理通过上调铁超氧化物歧化酶同工酶增强了铅诱导的根中 H2O2 的积累。在铅胁迫下，所有器官中的 GSH 氧化还原比仍然高度降低，而在观察到脂质过氧化产物增加和电解质渗漏的叶组织中，抗坏血酸氧化还原比下降。最后，发现脯氨酸和β-咔啉生物碱存在器官依赖性积累，表明这些氮氧化还原活性化合物可能在该物种对铅胁迫的适应策略中发挥作用。
