Effect of the Interaction between Elevated Carbon Dioxide and Iron Limitation on Proteomic Profiling of Soybean

Elevated atmospheric CO(2) (eCO(2)) and iron (Fe) availability are important factors affecting plant growth that may impact the proteomic profile of crop plants. In this study, soybean plants treated under Fe-limited (0.5 mM) and Fe-sufficient (20 mM) conditions were grown at ambient (400 μmol mol(−1)) and eCO(2) (800 μmol mol(−1)) in hydroponic solutions. Elevated CO(2) increased biomass from 2.14 to 3.14 g plant(−1) and from 1.18 to 2.91 g plant(−1) under Fe-sufficient and Fe-limited conditions, respectively, but did not affect leaf photosynthesis. Sugar concentration increased from 10.92 to 26.17 μmol g FW(−1) in roots of Fe-sufficient plants and from 8.75 to 19.89 μmol g FW(−1) of Fe-limited plants after exposure to eCO(2). In leaves, sugar concentration increased from 33.62 to 52.22 μmol g FW(−1) and from 34.80 to 46.70 μmol g FW(−1) in Fe-sufficient and Fe-limited conditions, respectively, under eCO(2). However, Fe-limitation decreases photosynthesis and biomass. Pathway enrichment analysis showed that cell wall organization, glutathione metabolism, photosynthesis, stress-related proteins, and biosynthesis of secondary compounds changed in root tissues to cope with Fe-stress. Moreover, under eCO(2), at sufficient or limited Fe supply, it was shown an increase in the abundance of proteins involved in glycolysis, starch and sucrose metabolism, biosynthesis of plant hormones gibberellins, and decreased levels of protein biosynthesis. Our results revealed that proteins and metabolic pathways related to Fe-limitation changed the effects of eCO(2) and negatively impacted soybean production.