Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Giessen, Germany.
Analytical Platform Stable Isotopes and Cell Biology, Institute of Nutritional Sciences, Justus Liebig University, Giessen, Germany.
BMC Plant Biol. 2024 Feb 2;24(1):83. doi: 10.1186/s12870-024-04756-8.
A sufficient nitrogen supply is crucial for high-quality wheat yields. However, the use of nitrogen fertilization can also negatively influence ecosystems due to leaching or volatile atmospheric emissions. Drought events, increasingly prevalent in many crop production areas, significantly impact nitrogen uptake. Breeding more efficient wheat varieties is necessary to achieve acceptable yields with limited nitrogen and water. Crop root systems play a crucial role as the primary organ for absorbing water and nutrients. To investigate the impact of an enhanced root system on nitrogen and water use efficiency in wheat under various irrigation conditions, this study conducted two experiments using precision phenotyping platforms for controlled drought stress treatment. Experiment 1 involved four contrasting winter wheat genotypes. It included the Chinese variety Ning0604, carrying a quantitative trait locus (QTL) on chromosome 5B associated with a higher root dry biomass, and three elite German varieties, Elixer, Genius, and Leandrus. Experiment 2 compared near-isogenic lines (NIL) of the three elite varieties, each containing introgressions of the QTL on chromosome 5B linked to root dry mass. In both experiments, nitrogen partitioning was tracked via isotope discrimination after fertilization with 5 Atom % N-labeled KNO.
In experiment 1 the quantification by N isotope discrimination revealed significantly (p < 0.05) higher nitrogen derived from fertilizer in the root organ for Ning0604 than those of the three German varieties. In experiment 2, two out of three NILs showed a significantly (p < 0.05) higher uptake of N derived from fertilizer than their respective recipient line under well-watered conditions. Furthermore, significantly lower transpiration rates (p < 0.1) were observed in one NIL compared to its respective recipient.
The combination of the DroughtSpotter facility coupled with N tracer-based tracking of N uptake and remobilization extends the insight into the impact of genetically altered root biomass on wheat NUE and WUE under different water availability scenarios. The study shows the potential for how a modified genetic constitution of the locus on wheat chromosome 5B can reduce transpiration and enhance N uptake. The dependence of the observations on the recipient and water availability suggests a need for further research to investigate the interaction with genetic background traits.
为了获得高质量的小麦产量，充足的氮供应至关重要。然而，由于淋溶或挥发性大气排放，氮肥的使用也会对生态系统产生负面影响。干旱事件在许多作物种植区越来越普遍，对氮的吸收有重大影响。培育更高效的小麦品种对于在有限的氮和水条件下实现可接受的产量是必要的。作物根系作为吸收水和养分的主要器官，起着至关重要的作用。为了研究在不同灌溉条件下增强根系对小麦氮素和水分利用效率的影响，本研究使用精密表型平台对受控干旱胁迫处理进行了两项实验。实验 1 涉及四个不同的冬小麦基因型。其中包括携带与根干生物量较高相关的 5B 染色体上数量性状位点（QTL）的中国品种宁 0604，以及三个德国优良品种艾利克斯、天才和利安德鲁斯。实验 2 比较了三个优良品种的近等基因系（NIL），每个品种都含有与根干质量相关的 5B 染色体上 QTL 的导入片段。在这两个实验中，通过在施肥后用 5 原子% 15N 标记的 KNO3 进行同位素标记，跟踪氮素的分配。
实验 1 通过氮同位素标记的定量分析表明，宁 0604 的根器官中来自肥料的氮素明显（p<0.05）高于三个德国品种。在实验 2 中，三个 NIL 中有两个在充分供水条件下，其从肥料中吸收的氮明显（p<0.05）高于各自的受体系。此外，与各自的受体相比，一个 NIL 的蒸腾速率显著（p<0.1）降低。
将 DroughtSpotter 设施与基于氮示踪剂的氮吸收和再利用跟踪相结合，扩展了对不同水分供应情景下遗传改变的根生物量对小麦氮利用效率和水分利用效率影响的认识。该研究展示了如何通过改变小麦 5B 染色体上的基因组成来减少蒸腾和提高氮吸收的潜力。这些观察结果对受体和水分可用性的依赖性表明，需要进一步研究以调查与遗传背景特征的相互作用。
