Excellence in Research: Antibiotics in the rhizosphere and resistance mechanisms in plants

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The goal of this project is to investigate the relationship between metal uptake and antibiotic resistance in plants. Plants mine the soil to extract minerals and in so doing, may take up antibiotics produced by soil microorganisms that adversely affect normal plant function. How plants maintain adequate nutrition while limiting the uptake of antibiotics is unknown. We specifically investigate metal uptake in the model plant Arabidopsis thaliana and its resistance to the antibiotic kanamycin. We propose a model in which the interplay among various transporters explains the trade-offs between metal uptake and antibiotic resistance. Our approach that combines mathematical modeling and experimental validation would allow us to examine these otherwise complex interactions that are not intuitive. Moreover the project provides an excellent opportunity for interdisciplinary training of undergraduate students at Spelman College, a Historically Black College for women. Overall, the project will contribute to enhancing the educational environment through research, curriculum and student development opportunities.Fe and Zn are among the most abundant micronutrients found in plants. Their uptake and movement in the plant is highly regulated. Our preliminary results showed a link between metal uptake in plants and antibiotic resistance. Most notably, Fe uptake declined in plants exposed to kanamycin. We propose a model that integrates what is known about Fe and Zn homeostasis with the effects of the antibiotic kanamycin. Besides Fe, Zn and kanamycin, other factors taken into consideration are the main chelators of Fe and Zn, citrate and nicotianamine (NA), and their known or assumed transporters. The model is centered on xylem loading, a critical step prior for the long distance transport of nutrients. A corresponding dynamic mathematical model based on a Generalized Mass Action system will be formulated and tested both computationally and biochemically. It is expected that this model will offer a new paradigm for understanding the link between metal nutrition and antibiotics in Arabidopsis and possibly crop species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.