Zinc distribution and localization in primed maize seeds and its translocation during early seedling development

Zinc (Zn) priming is a technique used to increase seed Zn reserves for improving seed quality, crop growth, and enhancing stress tolerance in crop plants. The present study demonstrated the effect of water and Zn priming on the distribution and accumulation of endogenous and primed Zn in maize seeds (Zea mays L.). Zn concentration in unprimed, water and Zn primed seeds and germinated seedlings were analyzed by ICP-MS (Inductivity Coupled Plasma Mass Spectroscopy). DTZ (Diphenyle Thio-Carbazone) staining method and LA-ICP-MS (Laser Ablation Inductivity Coupled Plasma Mass Spectroscopy) scanning was used for showing Zn distribution and localization in the seeds. Zn priming significantly increased Zn concentration and content in seeds. Results of ICP-MS analysis showed a substantial increase in the testa and endosperm tissues after Zn priming. DTZ staining and LA-ICP-MS scanning of maize seeds revealed an uneven distribution of Zn in water and Zn primed seeds. Laser ablation data of water primed maize seeds demonstrated a significant (p < 0.05) relocation of endogenous Zn from the aleurone layers towards the inner endosperm. Zn priming increased endosperm Zn content 3-fold compared with water primed seeds, while in the testa this increase was 50-fold. Furthermore, Zn priming significantly (p < 0.05) increased the biomass of 10-d old maize seedlings grown in rolls of filter paper. Translocation of primed Zn towards shoots and roots was double than that of endogenous Zn in unprimed and water primed maize seeds. This is the first report of the distribution and accumulation of primed Zn in maize seeds. Further investigations are needed to understand the binding capacity of the different tissues within maize seeds and the retranslocation of primed Zn during early seedling development and plant growth.