In this study, we undertook a comprehensive quantitative proteomic profiling of Arabidopsis roots from plants grown on Mn-deplete media, aiming at dissecting and cataloging the responses of Arabidopsis roots to Mn deficiency. We used LC-Q Exactive Orbitrap mass spectrometer to compile a near complete inventory of the Arabidopsis root proteome. We identified several novel components of cellular Mn homeostasis and show that many putatively important changes in response to Mn deficiency are only evident at one of the omics levels under investigation.