Comparative Proteomics Analysis Provides New Candidates for Zinc Homeostasis Regulation in Arabidopsis

Zinc (Zn) is an essential micronutrient for plants and around two billion people are depending on grains and legumes as their main Zn source. On the other hand, this transition metal is toxic for plants at high concentrations in soils. This calls for a better unravelling of Zn homeostasis regulation mechanisms, including sensing and signaling in plants. In order to fulfill this aim, we are testing for novel proteins involved in Zn homeostasis in the model plant Arabidopsis thaliana. First, quantitative proteomics was performed on root and shoot samples obtained upon Zn starvation and re-supply in different spatio-temporal conditions. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was also performed for those treatments to measure the Zn concentration in tissues. It showed very rapid Zn uptake in root upon re-supply. Moreover, quantitative expression studies of known players of Zn homeostasis confirmed our large-scale proteomic results, although for a few genes lack of correlation between transcript and protein regulation was observed. Using clustering, statistical and gene ontology analyses, we selected candidate genes for further studies. Among more than 5000 detected proteins in roots by shotgun proteomics, 75 genes were selected for targeted analyses. In general, our results show that comparative proteomics study can be useful to reveal new players in the Zn regulatory network in plants, which can lead to new Zn biofortification and phytoremediation strategies.