{"type": "FeatureCollection", "features": [{"id": "10.1111/nph.20145", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-26T16:18:57Z", "type": "Journal Article", "created": "2024-10-01", "title": "What determines transfer of carbon from plants to mycorrhizal fungi?", "description": "Summary

Biological Market Models are common evolutionary frameworks to understand the maintenance of mutualism in mycorrhizas. \uffe2\uff80\uff98Surplus C\uffe2\uff80\uff99 hypotheses provide an alternative framework where stoichiometry and source\uffe2\uff80\uff93sink dynamics govern mycorrhizal function. A critical difference between these frameworks is whether carbon transfer from plants is regulated by nutrient transfer from fungi or through source\uffe2\uff80\uff93sink dynamics. In this review, we: provide a historical perspective; summarize studies that asked whether plants transfer more carbon to fungi that transfer more nutrients; conduct a meta\uffe2\uff80\uff90analysis to assess whether mycorrhizal plant growth suppressions are related to carbon transfer; and review literature on cellular mechanisms for carbon transfer. In sum, current knowledge does not indicate that carbon transfer from plants is directly regulated by nutrient delivery from fungi. Further, mycorrhizal plant growth responses were linked to nutrient uptake rather than carbon transfer. These findings are more consistent with \uffe2\uff80\uff98Surplus C\uffe2\uff80\uff99 hypotheses than Biological Market Models. However, we also identify research gaps, and future research may uncover a mechanism directly linking carbon and nutrient transfer. Until then, we urge caution when applying economic terminology to describe mycorrhizas. We present a synthesis of ideas, consider knowledge gaps, and suggest experiments to advance the field.Biological Market Models are common evolutionary frameworks to understand the maintenance of mutualism in mycorrhizas. \uffe2\uff80\uff98Surplus C\uffe2\uff80\uff99 hypotheses provide an alternative framework where stoichiometry and source\uffe2\uff80\uff93sink dynamics govern mycorrhizal function. A critical difference between these frameworks is whether carbon transfer from plants is regulated by nutrient transfer from fungi or through source\uffe2\uff80\uff93sink dynamics. In this review, we: provide a historical perspective; summarize studies that asked whether plants transfer more carbon to fungi that transfer more nutrients; conduct a meta\uffe2\uff80\uff90analysis to assess whether mycorrhizal plant growth suppressions are related to carbon transfer; and review literature on cellular mechanisms for carbon transfer. In sum, current knowledge does not indicate that carbon transfer from plants is directly regulated by nutrient delivery from fungi. Further, mycorrhizal plant growth responses were linked to nutrient uptake rather than carbon transfer. These findings are more consistent with \uffe2\uff80\uff98Surplus C\uffe2\uff80\uff99 hypotheses than Biological Market Models. However, we also identify research gaps, and future research may uncover a mechanism directly linking carbon and nutrient transfer. Until then, we urge caution when applying economic terminology to describe mycorrhizas. We present a synthesis of ideas, consider knowledge gaps, and suggest experiments to advance the field.