Li Huiqiang, Zhu Xiaobo, Wang Junjun, Wei Yihao, Nai Furong, Yu Haidong, Wang Xiaochun
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, Henan, China; Research and Experiment Station of Nitrogen and Phosphorus Loss in Farmland of the Yellow River Basin in Henan Province, Zhengzhou 450000, China.
College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, Henan, China.
Plant Physiol Biochem. 2024 Jan;206:108278. doi: 10.1016/j.plaphy.2023.108278. Epub 2023 Dec 15.
Nitrogen uptake is crucial to wheat nitrogen use efficiency (NUE). The study's findings indicate that both high- and low-NUE cultivars exhibited highest nitrogen uptake efficiency (NupE) under 0.2 mM nitrogen. Under 2 mM nitrogen, their NupEs decrease significantly, while uptakes to NO were notably higher than that of NH. Strikingly, high-NUE cultivars exhibited a significantly higher NH uptake rate than low NUE cultivars, resulting in a marked improvement in their ability to take up nitrogen. The NUEs of the cultivars with 5 mM nitrogen were almost half that of 2 mM nitrogen. NO uptake primarily occurred in the mature zone of roots, while NH uptake took place in the root tip meristem and elongation zones. Notably, the NH uptake in root tip meristematic zone of high-NUE cultivar was significantly higher than that of low NUE cultivar. Furthermore, the NO uptake of high-NUE cultivar in the root mature zone was significantly higher than that of low-NUE cultivar under 2 mM nitrogen. These findings were consistent with the significantly higher expression levels of TaAMT in root tip and of TaNRT in root mature area of high-NUE cultivar compared to low-NUE cultivar, respectively, enabling efficient absorption of NO and NH and transport of NO to shoot. The high-NUE cultivars showed elevated expression of amino acid transporters further promoting nitrogen uptake, and conversion of nitrogen into ureides and amino acids further facilitated inorganic nitrogen uptake by roots. The differential findings offer valuable insights into novel variety breeding of high NUE in the future.
氮素吸收对小麦氮素利用效率（NUE）至关重要。该研究结果表明，高氮素利用效率和低氮素利用效率的品种在0.2 mM氮素条件下均表现出最高的氮素吸收效率（NupE）。在2 mM氮素条件下，它们的NupE显著降低，而对NO的吸收明显高于对NH的吸收。值得注意的是，高氮素利用效率品种的NH吸收速率显著高于低氮素利用效率品种，从而使其吸氮能力显著提高。5 mM氮素条件下品种的NUE几乎是2 mM氮素条件下的一半。NO吸收主要发生在根的成熟区，而NH吸收发生在根尖分生组织和伸长区。值得注意的是，高氮素利用效率品种根尖分生组织区的NH吸收显著高于低氮素利用效率品种。此外，在2 mM氮素条件下，高氮素利用效率品种根成熟区的NO吸收显著高于低氮素利用效率品种。这些发现与高氮素利用效率品种根尖中TaAMT和根成熟区中TaNRT的表达水平分别显著高于低氮素利用效率品种一致，从而能够有效吸收NO和NH并将NO运输到地上部。高氮素利用效率品种中氨基酸转运蛋白的表达升高进一步促进了氮素吸收，氮素向酰脲和氨基酸的转化进一步促进了根系对无机氮的吸收。这些差异发现为未来高氮素利用效率新品种的培育提供了有价值的见解。
