Real-Time Monitoring of Iron Uptake and Transport in Plants with Optical Nanosensor

Iron deficiency is a major global health concern, and dietary iron from plant consumption is a primary source for most people worldwide. However, the iron content in plants is heavily affected by various environmental and agronomic factors, including climate change such as rising temperature, water scarcity, and elevated atmospheric CO₂ level. Therefire, it is a pressing need to develop effective strategies to combat iron deficiency and ensure food security for the global population. Conventional analytical techniques to investigate the efficacy of foliar iron fertilization are not optimally suited to observe the nuances of foliar absorption, translocation, and iron speciation. This lack of information hampers the optimization of fertilization strategies and the development of more effective nutrient formulations.<br/><br/>In this work, we introduce a highly sensitive fluorescence iron nanosensor for elucidating the biochemistry of iron in plants, thereby enabling the formulation of precise fertilization strategies. This nanosensor can be easily incorporated into living plant species to monitor real-time iron uptake via both foliar and soil-based fertilizations. Our sensor, fabricated by conjugating a synthetic conjugated polymer onto single-walled carbon nanotubes, is designed to exhibit a unique orthogonal optical response that enables differentiation between Fe(II) and Fe(III).<br/><br/>Using hydroponically grown lettuce as a model for iron foliar application study, our sensor provides the means to monitor iron uptake, metabolism, and transport with high spatial and temporal resolution in the leaf tissues in real time. Our findings demonstrate that the plant's mechanistic responses to the source of iron species depend on the chelation state rather than the oxidation state. Under conditions of iron deficiency or simulated abiotic stress, such as drought or salt stress, the diffusion and transport rate of iron species are also affected. We also observe a shared mechanistic response to chelated iron species across various plant species, hinting at the existence of conserved foliar iron homeostatic mechanisms.<br/><br/>With its ability to offer detailed insights into the dynamics of iron uptake and transport in real-time, we believe this sensor technology has the potential to revolutionize the study of iron uptake and distribution in plants. This advancement can lead to improved plant growth and yield through the development of more precise and efficient micronutrient management strategies.