Zinc homeostasis in ectomycorrhizal symbiosis: nutrition and beyond

Mutualistic associations between tree roots and fungi,
ectomycorrhizas (ECMs), are ubiquitous. Through these
associations, trees can colonize, establish and survive in a wide
range of soils. Underground hyphal networks regulate nutrient access
and limit translocation of pollutants in exchange for plant derived
sugars. Traditionally, transport of macronutrients throughout the
fungal mycelium and towards the plant is well studied. However,
regulation of nutrient exchange and its impact on sustainability of the
mutualism remains unclear. Indeed, including micronutrients in the
current models of symbiotic transport is urgently needed to fully
understand establishment and resilience of ECM mutualism. The aim
of the current project is to unravel the role of micronutrient Zn in ECM
fungi and symbiosis. We will study Zn dynamics and trafficking upon
environmental change to evaluate the contribution of ECM fungi at
plant Zn balances and to explore the potential of Zn to act as a
molecular signal beyond its trophic role. Zn transporters of the CDF
and ZIP family will be characterized, and in-depth analysis of a
putative Zn responsive transcription factor will be performed. The
results of this study will contribute profound knowledge on Zn
homeostasis and gene regulation in ECM, linking cytoplasmic Zn
availability to adaptive growth responses. This will ultimately lead to a
better understanding of the pervasive power of ECM fungi in
terrestrial ecosystems