Cultivar-specific wheat-associated microbiomes and metabolites in response to nitrogen deficiency

Background and Aims Nitrogen (N) deficiency in soil constrains plant growth, which may potentially be alleviated by beneficial soil microbes. However, there is limited knowledge of the plant-microbe interactions of wheat cultivars with different N-use efficiency (NUE) under N deficiency. Methods We investigated the responses of soil and root endosphere microorganisms 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 that bacterial growth and motility in the rhizosphere of Mace, but not of Gladius, were potentially enhanced under N deficiency. A 4-fold increase in octadecanoic acid in the root extract 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 provides new evidence highlighting the divergent responses of wheat-associated microorganisms and root metabolites to N deficiency in the two cultivars. In addition to this, our findings suggest that wheat cultivars with higher NUE may selectively recruit beneficial bacterial communities through secreting specific metabolites, thereby enhancing their growth under N-limited conditions.