Kong Zhaoyu, Mohamad Osama Abdalla, Deng Zhenshan, Liu Xiaodong, Glick Bernard R, Wei Gehong
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.
Environ Sci Pollut Res Int. 2015 Aug;22(16):12479-89. doi: 10.1007/s11356-015-4530-7. Epub 2015 Apr 24.
The effects of rhizobial symbiosis on the growth, metal uptake, and antioxidant responses of Medicago lupulina in the presence of 200 mg kg(-1) Cu(2+) throughout different stages of symbiosis development were studied. The symbiosis with Sinorhizobium meliloti CCNWSX0020 induced an increase in plant growth and nitrogen content irrespective of the presence of Cu(2+). The total amount of Cu uptake of inoculated plants significantly increased by 34.0 and 120.4% in shoots and roots, respectively, compared with non-inoculated plants. However, although the rhizobial symbiosis promoted Cu accumulation both in shoots and roots, the increase in roots was much higher than in shoots, thus decreasing the translocation factor and helping Cu phytostabilization. The rate of lipid peroxidation was significantly decreased in both shoots and roots of inoculated vs. non-inoculated plants when measured either 8, 13, or 18 days post-inoculation. In comparison with non-inoculated plants, the activities of superoxide dismutase and ascorbate peroxidase of shoots of inoculated plants exposed to excess Cu were significantly elevated at different stages of symbiosis development; similar increases occurred in the activities of superoxide dismutase, catalase, and glutathione reductase of inoculated roots. The symbiosis with S. meliloti CCNWSX0020 also upregulated the corresponding genes involved in antioxidant responses in the plants treated with excess Cu. The results indicated that the rhizobial symbiosis with S. meliloti CCNWSX0020 not only enhanced plant growth and metal uptake but also improved the responses of plant antioxidant defense to excess Cu stress.
研究了在共生发育的不同阶段，根瘤菌共生对天蓝苜蓿在200 mg kg(-1) Cu(2+)存在下的生长、金属吸收和抗氧化反应的影响。与苜蓿中华根瘤菌CCNWSX0020的共生诱导了植物生长和氮含量的增加，而与Cu(2+)的存在无关。与未接种的植物相比，接种植物地上部和根部的铜吸收总量分别显著增加了34.0%和120.4%。然而，尽管根瘤菌共生促进了地上部和根部的铜积累，但根部的增加远高于地上部，从而降低了转运系数并有助于铜的植物稳定作用。接种后8、13或18天测量时，接种植物与未接种植物相比，地上部和根部的脂质过氧化率均显著降低。与未接种的植物相比，在共生发育的不同阶段，暴露于过量铜的接种植物地上部的超氧化物歧化酶和抗坏血酸过氧化物酶活性显著升高；接种根中的超氧化物歧化酶、过氧化氢酶和谷胱甘肽还原酶活性也有类似的增加。与苜蓿中华根瘤菌CCNWSX0020的共生还上调了过量铜处理植物中参与抗氧化反应的相应基因。结果表明，与苜蓿中华根瘤菌CCNWSX0020的根瘤菌共生不仅增强了植物生长和金属吸收，还改善了植物抗氧化防御对过量铜胁迫的反应。
