A non-canonical salicylic acid signaling network modulates root development and its microbiota composition in plants

Besides playing a crucial role in plant immunity via NPR proteins, increasing evidence shows that salicylic acid (SA) can also regulate plant root growth1–5. However, the transcriptional regulatory network controlling this SA response in plant roots is still unclear. Here, we reconstructed a novel root SA regulatory network, which conservedly modulates the root development and root-associated microbiota composition in both Oryza sativa (monocots) and Arabidopsis thaliana (dicots). We demonstrated that this root SA regulatory network is not controlled by the central regulators of SA response in plant leaves, NPR1 and WRKY45. Furthermore, we identified and validated the function of new regulatory players controlling root development in response to SA and impacting the root microbiota colonization. Our results established the SA signaling as a central element regulating plant root functions under ecologically relevant conditions. These results provide new insights to understand how regulatory networks control plant responses to abiotic and biotic stresses.