Bio-Inspired Proline Sensors for Diagnosis and Surveillance of Plant Stress

In response to environmental stresses such as drought, excessive salt, high temperatures, heavy metals, and pathogens, plants accumulate amino acids and other metabolites resulting from protective homeostatic processes. Specifically, the amino acid proline can counteract the effects of osmotic stress, chelate metals, and act as an antioxidant, resulting in increased concentrations of proline within plant tissue in response to environmental stimuli. While proline can serve as a general diagnostic indicator of plant or crop health, there are limited field-deployable options for measuring the proline content of plant tissue on-location without requirements for secondary equipment. We have developed bio-inspired proline sensors based on the coloration mechanism of <i>Nesocodon mauritianus</i>. The color of the nectar in this flowering plant, ranging from pale yellow to blood red, is directly dependent on both internal pH and proline concentration. By leveraging the chemistry of this natural system, we have developed colorimetric, paper-based proline sensors that provide quantifiable visible signals in response to increasing proline concentrations. We are integrating these sensors into biodegradable, user-friendly form factors that enable a plant-based, eco-friendly approach to monitoring plant health.