Background and Aims

Nitrogen (N) deficiency in soil constrains plant growth, which beneficial soil bacterial communities may potentially alleviate. However, there is limited knowledge of the plant-bacteria interactions of wheat cultivars with different N-use efficiency (NUE) under N deficiency.

Methods

We investigated the responses of soil and root endosphere bacterial communities as well as root metabolites of two wheat cultivars (cv. Mace and Gladius) with reported high and low NUE, respectively, using a glasshouse experiment and a hydroponic experiment with three N levels.

Results

The rhizosphere bacterial community of Mace shifted under N deficiency but not in its root endosphere. Conversely, the rhizosphere bacterial community of Gladius remained unchanged under N deficiency but shifted in its root endosphere. The metagenomic analysis illustrated increased detection of genes related to bacterial growth and motility in the rhizosphere of Mace, but not of Gladius, under N deficiency. A four-fold increase in octadecanoic acid in the root of Mace, but not Gladius, under N deficiency, suggesting the potential role of octadecanoic acid in shaping the rhizobacterial community in Mace with higher reported NUE.

Conclusion

Our study highlights the divergent responses of wheat-associated microorganisms and root metabolites to N deficiency in the two cultivars. We found that wheat cultivars with higher NUE increased octadecanoic acid secretion, potentially shaping the rhizobacterial communities and enhancing their growth under N-limited conditions.

中文翻译：

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响应氮缺乏的品种特异性小麦相关细菌群落和代谢物

 背景和目标

土壤中氮 （N） 缺乏会限制植物生长，而有益的土壤细菌群落可能会缓解这种情况。然而，关于缺氮下不同氮利用效率 （NUE） 的小麦品种的植物-细菌相互作用的认识有限。

 方法

我们使用温室实验和具有三个 N 水平的水培实验，研究了两个小麦品种 （cv. Mace 和 Gladius） 的土壤和根内圈细菌群落以及根系代谢物的反应，分别报告了高和低 NUE。

 结果

Mace 的根际细菌群落在缺氮下发生转移，但在其根内球中没有转移。相反，在缺氮的情况下，Gladius 的根际细菌群落保持不变，但在其根内圈发生了变化。宏基因组分析表明，在缺氮的情况下，Mace 而不是 Gladius 根际与细菌生长和运动相关的基因的检测增加。在缺氮的情况下，Mace 根中的十八烷酸增加了四倍，但 Gladius 没有增加，这表明十八烷酸在塑造 Nue 较高的 Mace 根际细菌群落中的潜在作用。

 结论

我们的研究强调了两个品种中小麦相关微生物和根系代谢物对氮缺乏的不同反应。我们发现，具有较高 NUE 的小麦品种增加了十八烷酸的分泌，可能塑造了根细菌群落并促进了它们在 N 限制条件下的生长。