Elbasan Fevzi, Ozfidan-Konakci Ceyda, Yildiztugay Evren, Kucukoduk Mustafa
Selcuk University, Faculty of Science, Department of Biotechnology, 42130, Konya, Turkey.
Necmettin Erbakan University, Faculty of Science, Department of Molecular Biology and Genetics, 42090, Konya, Turkey.
Plant Physiol Biochem. 2020 May 6;152:157-169. doi: 10.1016/j.plaphy.2020.04.040.
Oryza sativa L. cv. Gönen grown in hydroponic culture was treated with scandium (Sc; 25 and 50 μM) alone or in combination with salt (100 mM NaCl) and/or drought (5% PEG-6000). Stress caused a decrease in growth (RGR), water content (RWC), osmotic potential (Ψ), chlorophyll fluorescence (F/F) and potential photochemical efficiency (F/F). Sc application prevented the decreases of these parameters. Sc also alleviated the changes on gas exchange parameters (carbon assimilation rate (A), stomatal conductance (g), intercellular CO concentrations (C), transpiration rate (E) and stomatal limitation (L)). Stress caused no increase in superoxide dismutase (SOD) activity. After induvial applied NaCl or PEG, catalase (CAT) and ascorbate peroxidase (APX) showed an enhancement in activation and tried to scavenge of hydrogen peroxide (HO). On the other hand, in plants with the combination form of NaCl and PEG, only CAT activity was induced. Sc applications to NaCl-treated rice led to an increase of SOD, APX, glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) as well as peroxidase (POX). Sc under NaCl could be maintained both ascorbate (AsA) and glutathione (GSH) regeneration. Despite of induction of MDHAR and DHAR under Sc plus PEG, Sc did not maintain AsA redox state because of no induction in APX activity. However, GSH pool could be regenerated by induction in DHAR and GR in this group. Sc application (especially for 25 μM) in rice exposed to NaCl + PEG resulted an enhancement in APX and MDHAR and so Sc could be partially provided AsA regeneration. Since no increases in DHAR and GR were observed, GSH pool was reduced. Due to this activation of antioxidant enzymes, stress-induced HO and TBARS content (lipid peroxidation) significantly decreased in rice with Sc applications. Sc in plants with stress also increased the transcript levels of OsCDPK7 and OsBG1 related to stomatal movement and signaling pathway. Consequently, Sc protected the rice plants by minimizing disturbances caused by NaCl or PEG exposure via the AsA-GSH redox-based systems.
水培种植的水稻品种冈嫩（Oryza sativa L. cv. Gönen）单独用钪（Sc；25和50微摩尔）处理，或与盐（100毫摩尔氯化钠）和/或干旱（5%聚乙二醇-6000）联合处理。胁迫导致生长速率（RGR）、含水量（RWC）、渗透势（Ψ）、叶绿素荧光（F/F）和潜在光化学效率（F/F）降低。施用Sc可防止这些参数降低。Sc还减轻了气体交换参数（碳同化率（A）、气孔导度（g）、细胞间二氧化碳浓度（C）、蒸腾速率（E）和气孔限制（L））的变化。胁迫未导致超氧化物歧化酶（SOD）活性增加。单独施用氯化钠或聚乙二醇后，过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）的活性增强，并试图清除过氧化氢（HO）。另一方面，在氯化钠和聚乙二醇组合处理的植株中，仅诱导了CAT活性。对氯化钠处理的水稻施用Sc导致SOD、APX、谷胱甘肽还原酶（GR）、单脱氢抗坏血酸还原酶（MDHAR）、脱氢抗坏血酸还原酶（DHAR）以及过氧化物酶（POX）增加。在氯化钠胁迫下，Sc可维持抗坏血酸（AsA）和谷胱甘肽（GSH）的再生。尽管在Sc加聚乙二醇处理下诱导了MDHAR和DHAR，但由于APX活性未诱导，Sc未能维持AsA的氧化还原状态。然而，该组中DHAR和GR的诱导可使GSH库再生。在暴露于氯化钠+聚乙二醇的水稻中施用Sc（尤其是25微摩尔）导致APX和MDHAR增加，因此Sc可部分促进AsA的再生。由于未观察到DHAR和GR增加，GSH库减少。由于抗氧化酶的这种激活，在施用Sc的水稻中，胁迫诱导的HO和丙二醛含量（脂质过氧化）显著降低。胁迫条件下植物中的Sc还增加了与气孔运动和信号通路相关的OsCDPK7和OsBG1的转录水平。因此，Sc通过基于AsA-GSH氧化还原系统将氯化钠或聚乙二醇暴露引起的干扰降至最低，从而保护水稻植株。
