How plants control iron (Fe) homeostasis at the molecular level has been a matter of debate for several years. Tremendous efforts have led to the identification and characterization of several molecular actors regulating Fe uptake and partitioning within the plant (Gao et al., 2019; Gao et al., 2020). Nevertheless, one important long-standing question still remains unanswered. It relates to the nature of the long-distance signal that conveys, via the phloem sap, information of the Fe status of aerial tissues to the roots in order to coordinate root growth and Fe uptake with the demand of the plant (Grusak and Pezeshgi, 1996). The objective of this work is to find proteins and/or peptides that can relay leaves to root Fe status information in the model plant Arabidopsis thaliana. For this purpose, we aim at (1) improving phloem sap extraction protocol to optimize the number of detected proteins, (2) developing protocols to specifically extract, detect and identified peptides and (3) comparing phloem proteome and peptidome between plants (wild type and mutants affected in Fe long distance signaling) grown in contrasted Fe growth conditions (control, excess and deficiency). References: - Grusak, and Pezeshgi. 1996. Plant Physiology, 110:329-334. - Gao et al. 2019. Frontiers in Plant Science, 10:6. - Gao et al. 2020. The Plant Cell, 32: 508-524