Molecular interplay of symbiotic and defensive responses in the non-model legume Arachis hypogaea

Plants and their microbiome are constantly influenced by a wide range of signaling molecules. However, molecular signaling between plants and associated microorganisms has been mainly studied in individual interactions with symbiotic or pathogenic microorganisms. The aim of this work was to study the molecular crosstalk between the signaling pathways activated after the individual and simultaneous perception of rhizobial Nod factors (symbiotic elicitor), chitosan (defense responses elicitor) and surfactin (Induced Systemic Resistance elicitor) in peanut plants. Transcriptome sequencing databases and bioinformatics were used to identify a set of marker genes for symbiotic and defense pathways. Afterwards, qRT-PCR analyses were used to study the expression of these selected genes in response to Nod factors, chitosan and surfactin inoculation and combined treatments. Simultaneous inoculation of Nod factors and chitosan indicated the prevalence of plant defense responses over the symbiotic pathway. On the other hand, transcriptional profiles of the marker genes were not significantly modified in plants previously treated with surfactin and inoculated with Nod factors and chitosan with respect to individual inoculation of the defense elicitor molecule. Taken together, the results reveal a complex scenario of symbiotic and defense pathways activated by the simultaneous detection of different elicitor molecules and contribute to the knowledge of the molecular crosstalk between the symbiotic and defense pathways in legumes.