Summary Differences in soil mobility and assimilation costs between organic and inorganic nitrogen (N) compounds would hypothetically induce plant phenotypic plasticity to optimize acquisition of, and performance on, the different N forms. Here we evaluated this hypothesis experimentally and theoretically. We grew Arabidopsis in split‐root setups combined with stable isotope labelling to study uptake and distribution of carbon (C) and N from l‐glutamine (l‐gln) and NO3− and assessed the effect of the N source on biomass partitioning and carbon use efficiency (CUE). Analyses of stable isotopes showed that 40–48% of C acquired from l‐gln resided in plants, contributing 7–8% to total C of both shoots and roots. Plants grown on l‐gln exhibited increased root mass fraction and root hair length and a significantly lower N uptake rate per unit root biomass but displayed significantly enhanced CUE. Our data suggests that organic N nutrition is linked to a particular phenotype with extensive growth of roots and root hairs that optimizes for uptake of less mobile N forms. Increased CUE and lower N uptake per unit root growth may be key facets linked to the organic N phenotype.

中文翻译：

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植物有机氮营养：成本、收益和碳利用效率


摘要有机氮 （N） 化合物和无机氮 （N） 化合物之间土壤流动性和同化成本的差异将假设诱导植物表型可塑性，以优化不同 N 形式的获取和性能。在这里，我们从实验和理论上评估了这个假设。我们在分根设置中培养拟南芥，结合稳定同位素标记，研究 l-谷氨酰胺 （l-gln） 和 NO3− 中碳 （C） 和 N 的吸收和分布，并评估 N 源对生物量分配和碳利用效率 （CUE） 的影响。稳定同位素分析表明，从 l-gln 获得的 C 中有 40-48% 存在于植物中，占芽和根总碳的 7-8%。在 l-gln 上生长的植物表现出根质量分数和根毛长度增加，每单位根生物量的氮吸收率显著降低，但表现出显着增强的 CUE。我们的数据表明，有机氮营养与根和根毛广泛生长的特定表型有关，该表型优化了流动性较差的氮形式的吸收。CUE 增加和每单位根生长的氮吸收降低可能是与有机氮表型相关的关键方面。