Modulation of Phosphate Deficiency-Induced Metabolic Changes by Iron Availability in Arabidopsis thaliana

Concurrent suboptimal supply of several nutrients requires the coordination of nutrient-specific transcriptional, phenotypic, and metabolic changes in plants in order to optimize growth and development in most agricultural and natural ecosystems. Phosphate (P(i)) and iron (Fe) deficiency induce overlapping but mostly opposing transcriptional and root growth responses in Arabidopsis thaliana. On the metabolite level, P(i) deficiency negatively modulates Fe deficiency-induced coumarin accumulation, which is controlled by Fe as well as P(i) deficiency response regulators. Here, we report the impact of Fe availability on seedling growth under P(i) limiting conditions and on P(i) deficiency-induced accumulation of amino acids and organic acids, which play important roles in P(i) use efficiency. Fe deficiency in P(i) replete conditions hardly changed growth and metabolite profiles in roots and shoots of Arabidopsis thaliana, but partially rescued growth under conditions of P(i) starvation and severely modulated P(i) deficiency-induced metabolic adjustments. Analysis of T-DNA insertion lines revealed the concerted coordination of metabolic profiles by regulators of Fe (FIT, bHLH104, BRUTUS, PYE) as well as of P(i) (SPX1, PHR1, PHL1, bHLH32) starvation responses. The results show the interdependency of P(i) and Fe availability and the interplay between P(i) and Fe starvation signaling on the generation of plant metabolite profiles.