Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY, 14853, USA; Department of Soil Science, Federal University of Lavras, PO Box 3037, Lavras, MG, 37200-900, Brazil.
Department of Soil Science, Federal University of Lavras, PO Box 3037, Lavras, MG, 37200-900, Brazil.
Plant Physiol Biochem. 2020 Dec;157:328-338. doi: 10.1016/j.plaphy.2020.11.001. Epub 2020 Nov 6.
Selenium (Se) biofortification in crops provides a valuable strategy to enhance human Se intake. However, crops vary greatly with their capacity in tolerating and metabolizing/accumulating Se, and the basis underlying such variations remains to be fully understood. Here, we compared the effects of Se and its analog S treatments on plant growth and biochemical responses between a Se accumulator (arugula) and a non-accumulator (lettuce). Arugula exhibited an increased biomass production in comparison with untreated controls at a higher selenate concentration than lettuce (20 μM vs. 10 μM NaSeO), showing better tolerance to Se. Arugula accumulated 3-folds more Se and S than lettuce plants under the same treatments. However, the Se/S assimilation as assessed by ATP sulfurylase and O-acetylserine (thiol)lyase activities was comparable between arugula and lettuce plants. Approximately 4-fold higher levels of Se in proteins under the same doses of Se treatments were observed in arugula than in lettuce, indicating that Se accumulators have better tolerance to selenoamino acids in proteins. Noticeably, arugula showed 6-fold higher ascorbate peroxidase activity and produced over 5-fold more glutathione and non-protein thiols than lettuce plants, which suggest critical roles of antioxidants in Se tolerance. Taken together, our results show that the elevated Se tolerance of arugula compared to lettuce is most likely due to an efficient antioxidant defense system. This study provides further insights into our understanding of the difference in tolerating and metabolizing/accumulating Se between Se accumulators and non-accumulators.
硒（Se）在作物中的生物强化为提高人体硒摄入量提供了一个有价值的策略。然而，不同作物在耐受和代谢/积累硒的能力上存在很大差异，其基础仍有待充分理解。在这里，我们比较了硒及其类似物 S 处理对硒积累体（芝麻菜）和非积累体（生菜）植物生长和生化反应的影响。与未经处理的对照组相比，芝麻菜在高于硒酸盐浓度（20μM 对 10μM NaSeO）的情况下表现出更高的生物量生产，显示出对硒更好的耐受性。在相同处理下，芝麻菜比生菜积累了 3 倍的硒和硫。然而，根据三磷酸腺苷硫酸化酶和 O-乙酰丝氨酸（硫醇）裂解酶活性评估的硒/硫同化在芝麻菜和生菜之间是可比的。在相同剂量的硒处理下，芝麻菜中的蛋白质中硒含量约高 4 倍，而在生菜中则较低，表明硒积累体对蛋白质中的硒氨基酸具有更好的耐受性。值得注意的是，芝麻菜的抗坏血酸过氧化物酶活性比生菜高 6 倍，产生的谷胱甘肽和非蛋白硫醇比生菜高 5 倍以上，这表明抗氧化剂在硒耐受中起着关键作用。总之，我们的研究结果表明，与生菜相比，芝麻菜对硒的耐受性更高，这很可能是由于其具有有效的抗氧化防御系统。这项研究为我们理解硒积累体和非积累体之间在耐受和代谢/积累硒方面的差异提供了进一步的认识。
