State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
Int J Mol Sci. 2020 Feb 15;21(4):1320. doi: 10.3390/ijms21041320.
Improving nitrogen use efficiency (NUE) is very important for crops throughout the world. Rice mainly utilizes ammonium as an N source, but it also has four genes involved in nitrate transport. The transporter is important for maintaining cellular pH under mixed N supplies. Overexpression of this transporter driven by a ubiquitin promoter in rice greatly improved yield and NUE. This strategy for improving the NUE of crops may also be important for other cereals such as wheat and barley, which also face the challenges of nutrient uptake balance. To test this idea, we constructed transgenic barley lines overexpressing . These transgenic barley lines overexpressing the rice transporter exhibited improved growth, yield, and NUE. We demonstrated that family members and the partner protein were also up-regulated by nitrate treatment (0.2 mM) in the transgenic lines. This suggests that the expression of and other family members were all up-regulated in the transgenic barley to increase the efficiency of N uptake and usage. We also compared the ubiquitin (Ubi) and a phloem-specific (RSs1) promoter-driven expression of . The Ubi promoter failed to improve nutrient uptake balance, whereas the RSs1 promoter succeed in increasing the N, P, and Fe uptake balance. The nutrient uptake enhancement did not include Mn and Mg. Surprisingly, we found that the choice of promoter influenced the barley phenotype, not only increasing NUE and grain yield, but also improving nutrient uptake balance.
提高氮素利用效率（NUE）对全世界的作物都非常重要。水稻主要以铵态氮作为氮源，但它也有四个参与硝酸盐运输的基因。该转运蛋白对于在混合氮供应下维持细胞 pH 值很重要。在水稻中，由泛素启动子驱动的这种转运蛋白的过表达大大提高了产量和 NUE。这种提高作物 NUE 的策略对于其他谷物如小麦和大麦也可能很重要，因为它们也面临着养分吸收平衡的挑战。为了验证这一想法，我们构建了过表达 的转基因大麦品系。这些过表达水稻转运蛋白的转基因大麦品系表现出更好的生长、产量和 NUE。我们证明，硝酸盐处理（0.2mM）也会上调转基因系中的 家族成员和伴侣蛋白 。这表明，在转基因大麦中， 家族成员的表达都被上调，以提高氮的吸收和利用效率。我们还比较了泛素（Ubi）和韧皮部特异性（RSs1）启动子驱动的 的表达。泛素启动子未能改善养分吸收平衡，而 RSs1 启动子成功增加了氮、磷和铁的吸收平衡。养分吸收增强不包括锰和镁。令人惊讶的是，我们发现启动子的选择影响了大麦表型，不仅提高了 NUE 和籽粒产量，而且改善了养分吸收平衡。
