Abstract

Wheat (Triticum aestivum L.) production requires a large amount of nitrogen (N) supply because growers aim to achieve high grain yield and appropriate grain protein content simultaneously. A comprehensive understanding of the mechanisms that underpin efficient N usage at limited N in wheat can facilitate the development of new N-saving varieties in this major crop. Here, we performed comparative analysis of flag leaf responses to N availability in soft red winter wheat with contrasting N use efficiency (NUE); VA08MAS-369 (high NUE) and VA07W-415 (low NUE). This study demonstrated that accelerated senescence along with enhanced breakdown of protein and starch in flag leaves was correlated with higher grain yield, NUE for grain yield, and NUE for grain protein under N limitation. The more dramatic reductions in flag leaf N compounds and carbohydrate reserves in VA08MAS-369 were linked with significantly elevated expression of genes and enzymes associated with these metabolic pathways in this high NUE genotype. Consistent with the gene expression data, nitrate reductase, glutamine synthetase, and NAD-dependent glutamate dehydrogenase activities were highly induced under limited N in VA08MAS-369. It was previously reported that accelerated senescence contributes to increased grain protein content in wheat under regular N supply. This study provides molecular and physiological evidence that vigorous senescence and N remobilization also benefit grain yield under N deprivation.

摘要

小麦（小麦L.）的生产需要大量的氮（N）供应，因为种植者旨在同时实现高谷物产量和适当的谷物蛋白质含量。全面了解在有限的氮素下有效利用氮素的机制，可以促进这一主要作物上新的氮素节约型作物的开发。在这里，我们对旗叶对软红冬小麦氮素有效性的响应进行了比较分析，对比了氮素利用效率（NUE）。VA08MAS-369（高NUE）和VA07W-415（低NUE）。这项研究表明，在氮限制下，加速衰老以及增强旗叶中蛋白质和淀粉的分解与较高的籽粒产量，籽粒产量的NUE和籽粒蛋白质的NUE有关。在这种高NUE基因型中，VA08MAS-369的剑叶N化合物和碳水化合物储备的更显着减少与这些代谢途径相关基因和酶的表达显着升高有关。与基因表达数据一致，在VA08MAS-369中在有限的氮下高度诱导了硝酸还原酶，谷氨酰胺合成酶和NAD依赖性谷氨酸脱氢酶活性。以前有报道说，在有规律的氮供应下，加速衰老有助于增加小麦籽粒蛋白质含量。这项研究提供了分子和生理学证据，表明在氮缺乏的条件下，旺盛的衰老和固氮作用也有利于谷物产量。与基因表达数据一致，在VA08MAS-369中在有限的氮下高度诱导了硝酸还原酶，谷氨酰胺合成酶和NAD依赖性谷氨酸脱氢酶活性。以前有报道说，在有规律的氮供应下，加速衰老有助于增加小麦籽粒蛋白质含量。这项研究提供了分子和生理学证据，表明在氮缺乏的情况下，旺盛的衰老和固氮作用也有利于谷物产量。与基因表达数据一致，在VA08MAS-369中在有限的氮下高度诱导了硝酸还原酶，谷氨酰胺合成酶和NAD依赖性谷氨酸脱氢酶活性。以前有报道说，在有规律的氮供应下，加速衰老有助于增加小麦籽粒蛋白质含量。这项研究提供了分子和生理学证据，表明在氮缺乏的情况下，旺盛的衰老和固氮作用也有利于谷物产量。