Main conclusion

Early-stage low nitrogen priming promotes root growth and delays leaf senescence through gene expression, enhancing nitrogen absorption and assimilation in wheat seedlings, thereby alleviating growth inhibition under nitrogen deficit stress and supporting normal seedling development.

Abstract

Verifying the strategies to reduce the amount of nitrogen (N) fertilizer while maintaining high crop yields is important for improving crop N use efficiency (NUE) and protecting the environment. To determine whether low N (LN) priming (LNP) can alleviate the impact of N-deficit stress on the growth of wheat seedlings and improve their tolerance to N-deficit stress, we conducted hydroponic experiments using two wheat cultivars, Yangmai 158 (YM158, LN tolerant) and Zaoyangmai (ZYM, LN sensitive) to study the effects of LNP on wheat seedlings under N-deficit stress. N-deficit stress decreased the plant dry weight, leaf area, and leaf N content (LNC), while LNP could significantly reduce this reduction. Distinct sensitivities to N-deficit stress were observed between the wheat cultivars, with ZYM showing an early decrease in leaf N content compared to YM158, which exhibited a late-stage reduction. LNP promoted root growth, expanded N uptake area, and upregulated the expression of TaNRT1.1, TaNRT2.1, and TaNRT2.2 in wheat seedlings, suggesting that LNP can enhance root N uptake capacity to increase N accumulation in plants. In addition, LNP improved the activity of glutamine synthase (GS) to enhance the capacity of N assimilation of plants. The relative expression of TaGS1 in the lower leaves of priming and stress (PS) was lower than that of no priming and stress (NS) after LNP, indicating that the rate of N transfer from the lower leaves to the upper leaves became slower after LNP, which alleviated the senescence of the lower leaves. The relative expression of TaGS2 was significantly increased, which might be related to the enhanced photorespiratory ammonia assimilation capacity after LNP, which reduced the N loss and maintained higher LNC. Therefore, LNP in the early stage can improve the N absorption and assimilation ability and maintain the normal N supply to alleviate the inhibition of N-deficit stress in wheat seedlings.

中文翻译：

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低氮引发提高小麦幼苗的氮吸收和同化适应氮缺乏胁迫

主要结论

早期低氮引发通过基因表达促进根系生长、延缓叶片衰老，增强小麦幼苗对氮的吸收和同化，从而缓解氮亏胁迫下的生长抑制，支持幼苗的正常发育。

抽象的

验证在保持作物高产的同时减少氮肥用量的策略对于提高作物氮肥利用效率（NUE）和保护环境具有重要意义。为了确定低氮（LN）引发（LNP）是否可以减轻缺氮胁迫对小麦幼苗生长的影响，提高小麦幼苗对缺氮胁迫的耐受性，我们以扬麦158（YM158）两个小麦品种进行了水培试验。 、LN 耐受）和早阳麦（ZYM、LN 敏感）研究 LNP 对缺氮胁迫下小麦幼苗的影响。缺氮胁迫降低了植物干重、叶面积和叶片氮含量 (LNC)，而 LNP 可以显着减少这种减少。在小麦品种之间观察到对氮缺乏胁迫的不同敏感性，与 YM158 相比，ZYM 显示出叶片氮含量的早期降低，而 YM158 则表现出后期降低。 LNP促进根系生长，扩大氮素吸收面积，并上调小麦幼苗TaNRT1.1、TaNRT2.1和TaNRT2.2的表达，表明LNP可以增强根系氮素吸收能力，增加植物氮素积累。此外，LNP还能提高谷氨酰胺合成酶（GS）的活性，增强植物对氮素的同化能力。 LNP后启动和胁迫(PS)的下部叶中TaGS1的相对表达量低于未启动和胁迫(NS)的下部叶，表明LNP后N从下部叶向上部叶转移的速率变慢，缓解了下部叶片的衰老现象。TaGS2的相对表达量显着增加，这可能与LNP后光呼吸氨同化能力增强，减少氮素损失并维持较高的LNC有关。因此，前期施LNP可以提高氮素吸收同化能力，维持正常的氮素供应，缓解小麦幼苗氮素缺乏胁迫的抑制作用。