Aims

The alkaloid hordenine is one of the major allelochemicals involved in the allelopathic ability of barley (Hordeum vulgare L.), whose biosynthesis and accumulation is preferentially located in roots. Hordenine appears to have been unintentionally favored during domestication in modern and cultivated barley cultivars at the expense of another alkaloid, gramine. In this study, we assessed the content of hordenine and its two precursors, N-methyltyramine (NMT) and tyramine, in roots and root exudates of the modern spring barley cv. Solist, and particularly how they are affected due to nutrient deficiencies.

Methods

We monitored the three metabolites during the early phases of barley growth i.e., up to 8 days, applying HPLC time-course and both target and untargeted metabolomic approaches. Barley plants were grown either in full nutrient solutions or in specific nutrient shortage conditions (N, S, P and Fe).

Results

Results confirmed a strong decrease of the allelochemical accumulation (hordenine and the two precursors) in roots and in root exudates during both 24 h and 8 days time-course experiments. Yet, the overall tyramine content was approximately tenfold lower compared to the other two compounds. In addition, plants subjected to nitrogen (-N), sulfur (-S), phosphorus (-P) and iron (-Fe) deprivation showed nutrient-dependent accumulation of hordenine, N-methyltyramine and tyramine, as well as of other secondary metabolites. Indeed, the synthesis of hordenine and N-methyltyramine was trigged under nutrient deficiencies.

Conclusions

In conclusion, this study highlighted the impact of nutrient availability on the growth-dependent accumulation patterns of all the three compounds investigated in modern barley roots.

中文翻译：

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大麦根中含氮化感物质、矿物质营养和代谢特征之间的相互作用

目标

大麦生物碱是影响大麦( Hordeum vulgare L.)化感能力的主要化感化学物质之一，其生物合成和积累优先位于根部。在现代和栽培大麦品种的驯化过程中，大麦似乎无意中受到青睐，而牺牲了另一种生物碱禾本科。在这项研究中，我们评估了现代春大麦品种的根和根分泌物中大麦及其两种前体 N-甲基酪胺 (NMT) 和酪胺的含量。Solist，特别是它们如何因营养缺乏而受到影响。

方法

我们在大麦生长的早期阶段（即长达 8 天）监测了三种代谢物，应用 HPLC 时间进程以及目标和非目标代谢组学方法。大麦植物要么在全营养溶液中生长，要么在特定的营养缺乏条件（N、S、P 和 Fe）中生长。

结果

结果证实，在 24 小时和 8 天的时间进程实验中，根和根分泌物中的化感化学积累（大麦碱和两种前体）强烈减少。然而，与其他两种化合物相比，酪胺的总含量大约低了十倍。此外，遭受氮 (-N)、硫 (-S)、磷 (-P) 和铁 (-Fe) 剥夺的植物表现出大麦碱、N-甲基酪胺和酪胺以及其他次生物质的营养依赖性积累。代谢物。事实上，大麦碱和 N-甲基酪胺的合成是在营养缺乏的情况下触发的。

结论

总之，这项研究强调了养分有效性对现代大麦根中研究的所有三种化合物的生长依赖性积累模式的影响。