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Nutrient exchange in arbuscular mycorrhizal symbiosis from a thermodynamic point of view.

Research paper by Ingo I Dreyer, Olivia O Spitz, Kerstin K Kanonenberg, Karolin K Montag, Maria M Handrich, Sabahuddin S Ahmad, Stephan S Schott-Verdugo, Carlos C Navarro-Retamal, María E ME Rubio-Meléndez, Judith L JL Gomez-Porras, Janin J Riedelsberger, Marco A MA Molina-Montenegro, Antonella A Succurro, Alga A Zuccaro, Sven B SB Gould, et al.

Indexed on: 20 Dec '18Published on: 20 Dec '18Published in: New Phytologist



Abstract

To get insights into the dynamics of nutrient exchange in arbuscular mycorrhizal (AM) symbiosis, we modelled mathematically the two-membrane system at the plant-fungus interface and simulated its dynamics. In computational cell biology experiments, the full range of nutrient transport pathways was tested for their ability to exchange phosphorus (P) / carbon (C) / nitrogen (N) sources. As a result, we obtained a thermodynamically justified, independent, and comprehensive model of the dynamics of the nutrient exchange at the plant-fungus contact zone. The predicted optimal transporter network coincides with the transporter set independently confirmed in wet-lab experiments previously, indicating that all essential transporter types have been discovered. The thermodynamic analyses suggest that phosphate is released from the fungus via proton-coupled phosphate transporters rather than anion channels. Optimal transport pathways, such as cation channels or proton-coupled symporters, shuttle nutrients along with a positive charge across the membranes. Only in exceptional cases, also the electroneutral transport via diffusion facilitators appears plausible. The thermodynamic models presented here can be generalised and adapted to other forms of mycorrhiza and open the door for future studies combining wet-lab experiments with computational simulations to obtain a deeper understanding of the investigated phenomena. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.