Anouk Van't Padje1,2, Gijsbert D A Werner3,4, E Toby Kiers2. 1. Laboratory of Genetics, Wageningen University & Research, Droevendaalsesteeg 1, Wageningen, 6708 PB, the Netherlands. 2. Department of Ecological Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit, de Boelelaan 1085, Amsterdam, 1081 HV, the Netherlands. 3. Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK. 4. Netherlands Scientific Council for Government Policy, Buitenhof 34, The Hague, 2513 AH, the Netherlands.
Abstract
Biological market theory provides a conceptual framework to analyse trade strategies in symbiotic partnerships. A key prediction of biological market theory is that individuals can influence resource value - meaning the amount a partner is willing to pay for it - by mediating where and when it is traded. The arbuscular mycorrhizal symbiosis, characterised by roots and fungi trading phosphorus and carbon, shows many features of a biological market. However, it is unknown if or how fungi can control phosphorus value when exposed to abrupt changes in their trade environment. We mimicked an economic 'crash', manually severing part of the fungal network (Rhizophagus irregularis) to restrict resource access, and an economic 'boom' through phosphorus additions. We quantified trading strategies over a 3-wk period using a recently developed technique that allowed us to tag rock phosphate with fluorescing quantum dots of three different colours. We found that the fungus: compensated for resource loss in the 'crash' treatment by transferring phosphorus from alternative pools closer to the host root (Daucus carota); and stored the surplus nutrients in the 'boom' treatment until root demand increased. By mediating from where, when and how much phosphorus was transferred to the host, the fungus successfully controlled resource value.
Biological market theory provides a conceptual framework to analyse trade strategies in symbiotic partnerships. A key prediction of biological market theory is that individuals can influence resource value - meaning the amount a partner is willing to pay for it - by mediating where and when it is traded. The arbuscular mycorrhizal symbiosis, characterised by roots and fungi trading class="Chemical">phosphorus aclass="Chemical">nd class="Chemical">n class="Chemical">carbon, shows many features of a biological market. However, it is unknown if or how fungi can control phosphorus value when exposed to abrupt changes in their trade environment. We mimicked an economic 'crash', manually severing part of the fungal network (Rhizophagus irregularis) to restrict resource access, and an economic 'boom' through phosphorus additions. We quantified trading strategies over a 3-wk period using a recently developed technique that allowed us to tag rock phosphate with fluorescing quantum dots of three different colours. We found that the fungus: compensated for resource loss in the 'crash' treatment by transferring phosphorus from alternative pools closer to the host root (Daucus carota); and stored the surplus nutrients in the 'boom' treatment until root demand increased. By mediating from where, when and how much phosphorus was transferred to the host, the fungus successfully controlled resource value.
Authors: Anouk van 't Padje; Malin Klein; Victor Caldas; Loreto Oyarte Galvez; Cathleen Broersma; Nicky Hoebe; Ian R Sanders; Thomas Shimizu; E Toby Kiers Journal: Ecol Lett Date: 2021-12-31 Impact factor: 11.274