Background

Phosphorus is an essential element for crop development that plays a vital role in biological processes such as photosynthesis, nutrient transportation, and energy transfer. In the realm of modern agriculture, the global demand for food production has experienced an incessant upward trajectory, driven by population growth and evolving dietary preferences. You see, the plant itself cannot directly use the insoluble phosphate salts from the rocks. That's why these phosphate minerals need to be processed into fertilizers, by coupling with potassium and ammonium ions, to make them more acquirable for our Crops.

However, one of the pivotal issues that plagues phosphate utilization in agriculture is the highly inefficient uptake of this essential nutrient by plants. Since phosphate is very reactive, and most of the phosphate in the fertilizers went back to insoluble forms when they meet calcium and other earth elements in the soil before they are absorbed in plant. Although the phosphorus content in the soil is large, most of the phosphorus cannot be absorbed by plants and uses ineffective phosphorus. Only 10-25% of the phosphorus applied to soil in the current season can be absorbed and utilized by plants. That is, about 80% of the phosphorus applied to the soil each year is wasted. As a result, to enhance the crop production, we continue to dig out and extract resources from our planet, at a rate that the known mineral phosphate reserves are estimated to deplete within the next 50 to 100 years.

This inefficiency not only results in substantial resource wastage but also contributes to a plethora of environmental problems. Phosphate runoff from agricultural fields often leads to eutrophication in water bodies, causing harmful algal blooms, dead zones, and severe damage to aquatic ecosystems. Excessive accumulation of phosphorus in soil is a potential threat to the water environment. Some studies have shown that the water-soluble phosphorus content of vegetable fields in facilities is high, the adsorption saturation of phosphorus is high, and the risk of leaching is high.

Our design

In response to these multifaceted challenges, our project introduces a comprehensive and multifaceted approach. At its core, our groundbreaking "phytosensor" revolutionizes the way we monitor phosphate levels within plants. This ingenious gene circuit comprises a low-phosphate-responsive promoter, an advanced low-noise expression amplifier part, and a highly luminous GFP as a reporter. The incorporation of this technology enables real-time monitoring of a plant's phosphorus status, thus providing valuable insights into its nutrient health. The utilization of a bright GFP protein as a reporter allows plant caretakers to visually assess the plant's phosphate status with ease, as it fluoresces brightly under UV light. Therefore, empowers farmers and plant scientists to make informed decisions about phosphate supplementation, ensuring that plants receive precisely what they need without the risk of overapplying fertilizers, without those expensive analytical devices. When entering the plant cells, the sensor detects the low-phosphate stress with its low-phosphate-responsive promoter. This signal then enters the amplifier system, through an artificial pathway with super-cool artificial transcription factors, that eventually yields a large quantity of super bright GFP protein that can be seen under UV light with the naked eye!

Moreover, the whole gene circuit was delivered into plants by the carbon nano bots developed by Soochow University and our team. This kind of patent material can deliver our gene circuit into plants' leaves in 3-5 days after spaying the material onto the leaves!

Complementing the phytosensor is our intelligent phosphorus fertilizer system. Our inspiration came from the team Nanjing_high_school 2020. In our design, the system harnesses the power of specially engineered bacteria that respond to low-phosphate stress signals emanating from plant roots. When activated, these bacteria produce and secrete gluconic acid, a naturally occurring compound renowned for its ability to enhance the solubility of calcium salts in the soil. This ingenious mechanism effectively mobilizes otherwise insoluble phosphate salts, rendering them accessible to plants in a form they can readily absorb. By dramatically enhancing phosphate utilization in the soil, this system serves as a game-changer, not only significantly boosting crop productivity but also mitigating the environmental repercussions associated with excessive fertilizer application.

Sustainable development goals

The environmental benefits of this system are substantial and align with several Sustainable Development Goals (SDGs). By reducing phosphate runoff from agricultural fields, we can mitigate the adverse effects of eutrophication in water bodies, including harmful algal blooms, which have far-reaching ecological and economic consequences. These blooms disrupt aquatic ecosystems, endanger aquatic life, and pose health risks to humans through the consumption of contaminated water and seafood. Moreover, by enhancing phosphate utilization in the soil, our system contributes to reducing the ecological footprint of agriculture, minimizing the need for resource-intensive processes like mining, processing, and transporting phosphate rock. This not only conserves finite resources but also lowers the carbon footprint of agricultural practices, supporting SDG 12: Responsible Consumption and Production by promoting sustainable use of phosphate fertilizers and responsible production and consumption patterns. Additionally, phosphate fertilizers can contribute to greenhouse gas emissions, such as nitrous oxide, which impacts climate change. Sustainable agricultural practices, including responsible fertilizer use, are crucial for mitigating climate change and reducing carbon emissions, aligning with SDG 13: Climate Action. Furthermore, phosphate mining and fertilizer runoff can negatively impact both aquatic ecosystems (SDG 14: Life Below Water) and terrestrial biodiversity (SDG 15: Life on Land). Sustainable practices in the production and use of phosphate fertilizers can help protect these ecosystems. In summary, our system's reduced need for excessive fertilizer application addresses multiple SDGs, resulting in less environmental impact on land and water.

Conclusion

Our project's impact extends beyond the confines of individual fields or farms. The global implications are profound. By improving phosphate management and reducing waste, we can extend the lifespan of known phosphate reserves. This, in turn, mitigates the looming risk of phosphate scarcity, which could have far-reaching geopolitical consequences. Countries heavily reliant on phosphate imports for their agricultural productivity may face increased economic vulnerabilities, potentially leading to food security challenges.

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