A plant protein used to communicate with friendly soil fungi has been identified by Cambridge University scientists.
Our soil is full of microscopic life including many species of mycorrhizal fungi which form huge networks through the soil.
Many plants team up with these soil fungi which provide minerals in return for sugars produced by the plant. This type of relationship is known as a symbiosis.
Until recently it was unclear how the plant roots and fungus communicated with each other to facilitate this trade.
Research using genetic techniques, published Science, has shown how plants can signal and detect their fungal neighbours.
"What we have found in this paper is a plant protein, actually from rice in this case, that is central for the perception of the these fungi in the soil," explained author Uta Paszkowski from Cambridge University.
The researchers started with a plant that had several genetic mutations and was unable to communicate with fungi. Over several years they were able to narrow down which of these mutations was responsible for the lack of symbiosis and, therefore, identify the gene essential to successfully communicating with soil fungi in normal plants.
"As a surprise, we found a protein that not only is central to this recognition of the fungus, but is actually quite well known already, as a protein that mediates smoke detection." Paszkowski commented.
The protein, known as karrikin, has been studied as a plant growth regulator that also mediates the perception of light and, in fire adapted species, detection of smoke.
Plants have been around on planet Earth for around 450 million years. Early land plants which first colonized terrestrial habitats were rootless. Roots evolved millions and millions of years later but fossil records show these ancestral plants lived in association with beneficial fungi.
It may be that "because of this association, plants could make the transition from water to land," Dr Paszkowski explained.
This important beneficial relationship between plants and soil fungi can still be seen in most plants today, including the majority of crops.
Dr Paszkowski is excited about the potential to use her research to solve the challenges of food production. "Something we are interested in is the potential of this symbiosis to be implemented into sustainable agricultural practices as biofertiliser."
Soil fungi are useful because they provide the plants with essential minerals currently provided by industrially produced fertilisers.
Establishing how plants communicate to initiate this trade of resources is an important step towards optimising the plant-fungus relationship in crop production.