Citrus grandis seedlings were irrigated with nutrient solutions containing two levels of aluminium (Al; 0 mM and 1.2 mM AlCl3•6H2O) and two levels of phosphorus (P; 0 μM and 200 μM KH2PO4) combinations for 18 weeks, respectively. The proteome profile of Citrus root submitted to different P-Al interactions were investigated by using isobaric tags for relative and absolute quantification (iTRAQ).