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Abstract：
In this paper, the effects of 100 mM NaCl and NaHCO3 stress on reactive oxygen species (ROS) and physiological and proteomic aspects of ROS metabolism in mulberry seedling leaves were studied. The results showed that NaCl stress had little effect on photosynthesis and respiration of mulberry seedling leaves. Superoxide dismutase (SOD) activity and the expression of related proteins in leaves increased by varying degrees, and accumulation of superoxide anion (O2·-) not observed. Under NaHCO3 stress, photosynthesis and respiration were significantly inhibited, while the rate of O2·- production rate and H2O2 content increased. The activity of catalase (CAT) and the expression of CAT (W9RJ43) increased under NaCl stress. In response to NaHCO3 stress, the activity and expression of CAT were significantly decreased, but the ability of H2O2 scavenging of peroxidase (POD) was enhanced. The ascorbic acid-glutathione (AsA-GSH) cycle in mulberry seedling leaves was enhancement in both NaCl and NaHCO3 stress. The expression of 2-Cys peroxiredoxin BAS1 (2-Cys Prx BAS1), together with thioredoxin F (TrxF), thioredoxin O1 (TrxO1), thioredoxin-like protein CITRX (Trx CITRX), and thioredoxin-like protein CDSP32 (Trx CDSP32) were significantly increased under NaCl stress. Under NaHCO3 stress, the expression of the electron donor of ferredoxin-thioredoxin reductase (FTR), together with Trx-related proteins, such as thioredoxin M (TrxM), thioredoxin M4 (TrxM4), thioredoxin X (TrxX), TrxF, and Trx CSDP32 were significantly decreased, suggesting that the thioredoxin-peroxiredoxin (Trx-Prx) pathway\'s function of scavenging H2O2 of in mulberry seedling leaves was inhibited. Taken together, under NaCl stress, excessive production of O2·- mulberry seedlings leaves was inhibited, and H2O2 was effectively scavenged by CAT, AsA-GSH cycle and Trx-Prx pathway. Under NaHCO3 stress, despite the enhanced functions of POD and AsA-GSH cycle, the scavenging of O2·- by SOD was not effective, and that of H2O2 by CAT and Trx-Prx pathway were inhibited; and in turn, the oxidative damage to mulberry seedling leaves could not be reduced.
摘要：
在本文中,研究了100mMNaCl和NaHCO3胁迫对桑树幼苗叶片活性氧（ROS）以及ROS代谢的生理和蛋白质组学方面的影响。结果表明,NaCl胁迫对桑树幼苗叶片的光合作用和呼吸作用影响不大。叶片中超氧化物歧化酶(SOD)活性和相关蛋白的表达均有不同程度的增加,并没有观察到超氧阴离子（O2·-）的积累。在NaHCO3压力下，光合作用和呼吸作用受到显著抑制,而O2·-产率和H2O2含量增加。NaCl胁迫下过氧化氢酶(CAT)活性和CAT(W9RJ43)表达量增加。响应NaHCO3的压力，CAT的活性和表达显著降低,但过氧化氢清除过氧化物酶（POD）的能力增强。在NaCl和NaHCO3胁迫下，桑树幼苗叶片中的抗坏血酸-谷胱甘肽（AsA-GSH）循环均增强。2-Cys过氧化物酶BAS1(2-CysPrxBAS1)的表达,与硫氧还蛋白F（TrxF）一起，硫氧还蛋白O1（TrxO1），硫氧还蛋白样蛋白TRX（TrxCITRX），在NaCl胁迫下，硫氧还蛋白样蛋白CDSP32（TrxCDSP32）显着增加。在NaHCO3压力下，铁氧还蛋白-硫氧还蛋白还原酶（FTR）的电子供体的表达，与Trx相关的蛋白质，如硫氧还蛋白M(TrxM)，硫氧还蛋白M4(TrxM4),硫氧还蛋白X(TrxX),TrxF,和TrxCSDP32显著下降，表明硫氧还蛋白-过氧化物酶（Trx-Prx）途径清除桑树幼苗叶片中H2O2的功能受到抑制。一起来看,在NaCl胁迫下，O2·-桑树幼苗叶片的过量产生被抑制，过氧化氢被CAT有效清除，AsA-GSH循环和Trx-Prx通路。在NaHCO3压力下，尽管POD和AsA-GSH循环的功能增强，SOD对O2·-的清除效果不佳，过氧化氢通过CAT和Trx-Prx途径被抑制；反过来，桑树幼苗叶片的氧化损伤不能减轻。
