Vuletić M, Hadži-Tašković Šukalović V, Marković K, Kravić N, Vučinić Ž, Maksimović V
Maize Research Institute, Zemun Polje, Belgrade, Serbia.
Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia.
Plant Biol (Stuttg). 2014 Jan;16(1):88-96. doi: 10.1111/plb.12017. Epub 2013 Apr 10.
An analysis of peroxidase and ascorbate oxidase activity, phenolic content and antioxidant capacity of isolated maize root cell walls was performed in controls and plants stressed with polyethylene glycol (PEG) or heavy metals, zinc or copper. Peroxidase activity (oxidative and peroxidative) was more pronounced in the ionic than in the covalent cell wall fraction. PEG induced an increase and Zn(2+) a decrease of both ionically bound peroxidase activities. In the covalent fraction, Cu(2+) decreased oxidative and increased peroxidative activity of peroxidase. Isoelectric focusing of ionically bound proteins and activity staining for peroxidase demonstrated increased intensities and appearance of new acidic isoforms, especially in Zn(2+) and PEG treatments. Most pronounced basic isoforms (pI ~ 7.5) in controls, decreased in intensity or completely disappeared in stressed plants. Ascorbate oxidase activity was significantly increased by PEG and decreased by Zn(2+) treatments, and highly correlated with peroxidase activity. Antioxidant capacity and total phenolics content increased in heavy metal-treated and decreased in PEG-treated plants. Analysis of individual phenolic components revealed p-coumaric and ferulic acids, as the most abundant, as well as ferulic acid dimers, trimers and tetramers in the cell walls; their quantity increased under stress conditions. Results presented demonstrate the existence of diverse mechanisms of plant response to different stresses.
对对照植株以及用聚乙二醇(PEG)或重金属锌或铜胁迫处理的植株中分离出的玉米根细胞壁的过氧化物酶和抗坏血酸氧化酶活性、酚类物质含量及抗氧化能力进行了分析。过氧化物酶活性(氧化活性和过氧化物活性)在离子键结合的细胞壁组分中比在共价键结合的细胞壁组分中更显著。PEG诱导离子结合的过氧化物酶活性增加,而Zn(2+)则使其降低。在共价键结合组分中,Cu(2+)降低了过氧化物酶的氧化活性并增加了其过氧化物活性。对离子结合蛋白进行等电聚焦以及对过氧化物酶进行活性染色显示,尤其是在Zn(2+)和PEG处理中,强度增加且出现了新的酸性同工型。对照中最明显的碱性同工型(pI ~ 7.5)在胁迫植株中强度降低或完全消失。PEG处理显著增加了抗坏血酸氧化酶活性,而Zn(2+)处理则使其降低,且抗坏血酸氧化酶活性与过氧化物酶活性高度相关。抗氧化能力和总酚类物质含量在重金属处理的植株中增加,而在PEG处理的植株中降低。对单个酚类成分的分析表明,对香豆酸和阿魏酸是细胞壁中含量最丰富的成分,同时还存在阿魏酸二聚体、三聚体和四聚体;在胁迫条件下它们的含量增加。所呈现的结果表明植物对不同胁迫存在多种响应机制。