# Mechanisms of Differential Resource Uptake and Translocation in Agaricus bisporus

## TL;DR

This study explores how Agaricus bisporus fungi transport nutrients like water, carbon, and nitrogen within their network to feed mushrooms, revealing that the top compost layer is a key source and specialized cells aid transport.

## Contribution

The study identifies specialized cell types in fungal cords and highlights the top compost layer as a primary nutrient source for mushrooms.

## Key findings

- Ammonium-derived 15N is transported from the center to the periphery of colonies, but glucose-derived 13C is not.
- The top compost layer contributes most to feeding mushrooms, regardless of mycelium network structure.
- Specialized cell types within cords likely facilitate nutrient transport.

## Abstract

Mushroom‐forming fungi form interconnected networks of hyphae and cords that cooperate to colonise their environment and feed developing mushrooms. To fully enable this cooperation, transport across the network is essential for the collection and delivery of resources when and where needed. It is not known to what extent, and with which resources, specific parts of the network contribute to feeding the developing mycelium and mushrooms. In this study, we investigated the translocation patterns of water, carbon and nitrogen in Agaricus bisporus, using stable isotope tracers. Ammonium‐derived 15N, but not glucose‐derived 13C, was consistently transported from the centre to the periphery of colonies in axenic culturing conditions. External wicking along the hyphae is likely a major translocation mechanism. Throughout the compost bed, there was 13C and 15N transport towards the mycelium colonising the casing and the developing mushrooms. Moreover, the top compost layer contributed most to feeding the growing mushrooms, irrespective of the mycelium network architecture. Within cords, we found five cell types of which one is likely specialised for nutrient transport. Overall, these findings provide new insights into nutrient uptake and translocation mechanisms in A. bisporus. This knowledge may ultimately enable enhanced feeding of mushrooms to improve production efficiency.

Tracer translocation happens to growing mycelium and mushrooms, but less so within the substrate. Mushrooms take tracers predominantly from the top layer of compost. Cords facilitate nutrient transport via specialized vessel hyphae.