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

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.

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.

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.

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.