Activation of the salicylic acid signalling pathway in wheat had no significant short-term impact on the diversity of root-associated microbiomes

Salicylic acid (SA) plays an important role in plant defence against biotrophic pathogens. Recent work with Arabidopsis thaliana mutants indicates an association between SA signalling and the diversity of root-associated microbial communities. This has led to the idea that activation of the SA pathway may help plants to rapidly recruit microbes that enhance stress tolerance and could be exploited as an approach to engineer beneficial plant microbiomes in agriculture. Nonetheless, unlike plants in natural environments, mutants with altered SA signalling constitutively express their phenotype. For this reason, we investigated whether transient activation of the SA pathway in wheat (Triticum aestivum) leads to rapid changes in the composition of root microbiomes. High throughput phylogenetic marker gene sequencing demonstrated that, 72 h post-treatment, SA had no significant effects on the richness, evenness and composition of bulk soil and root-associated microbiomes in two soil types. These findings indicate that the structure of wheat root-associated microbiomes did not undergo significant rapid changes in response to activation of the SA signalling pathway.