Molecular exchange at the plant-fungal interface in arbuscular mycorrhiza symbiosis

Nutrient acquisition is the basis of life.

Arbuscular mycorrhiza (AM) symbiosis of plants with nutrient-delivering fungi is detected in the oldest land plant fossils and considered a prerequisite for plant life on land. It is wide-spread in the plant kingdom and its secondary loss is the exception. AM improves plant nutrition, stress resistance and general plant performance.

Breeding AM-optimized crops has significant potential for improving food security and sustainable agriculture. Understanding the molecular underpinnings of AM function is thus imperative.

The hallmark of the symbiosis are the arbuscules, highly branched hyphal structures, which develop in root cortex cells. They build a large membrane interface with the plant derived peri-arbuscular membrane (PAM) that surrounds them.

Most mineral nutrients are delivered from the arbuscules and taken up via the PAM into plant cells through transporter proteins. In return, the fungi receive up to 20% of the photosynthetically-fixed carbon. The balance in mineral-nutrient-gain-for-carbon-loss influences the effect of the symbiosis in plant growth and yield.

However, the full range of transported nutrients, any mechanisms regulating transport and the balance in molecular exchange are unknown. ‘SymbioticExchange’ strategically integrates transcriptomics, phosphoproteomics, metabolomics and protein-protein interaction analysis, with reverse genetics, cell biology and transport physiology to identify novel plant and fungal transporters involved in symbiotic nutrient and metabolite exchange, and to understand the molecular mechanisms of their regulation. ‘SymbioticExchange’ will thus deliver major advances on the range of transporters at the plant-fungal interface, the exchanged goods and the regulation of exchange.

This important knowledge-base will provide crucial clues on how nutrient exchange can be tuned for profitable agricultural application of one of the most important symbioses on earth.