Proteomic Signatures Uncover Hydrogen Peroxide and Nitric Oxide Cross-Talk Signaling Network in Citrus Plants

Hydrogen peroxide (H2O2) and nitric oxide ((NO)-N-center dot) elicit numerous processes in plants. However, our knowledge of H2O2 and (NO)-N-center dot-responsive proteins is limited. The present study aimed to identify proteins whose accumulation levels were regulated by these signaling molecules in citrus leaves. To address this question, hydroponically grown citrus plants were treated by incubating their roots in the presence of H2O2 or the (NO)-N-center dot donor, sodium nitroprusside (SNP). Both treatments induced H2O2 and (NO)-N-center dot production in leaves, indicating occurrence of oxidative and nitrosative stress conditions. However, treated plants maintained their normal physiological status. The vascular system was shown to be involved in the H2O2 and (NO)-N-center dot systemic signaling as evidenced by real-time labeling of the two molecules. Comparative proteomic analysis identified a number of proteins whose accumulation levels were altered by treatments. They were mainly involved in photosynthesis, defense and energy. More than half of them were commonly modulated by both treatments, indicating a strong overlap between H2O2 and (NO)-N-center dot responses. Using a redox proteomic approach, several proteins were also identified as being carbonylation targets of H2O2 and SNP. The analysis reveals an interlinked H2O2 and (NO)-N-center dot proteins network allowing a deeper understanding of oxidative and nitrosative signaling in plants.