New light shed on battleground between soil and roots

The soil around roots of plants such as barley – one of our most important crops - is a battleground where only certain bacteria can survive, suggests evidence gathered by a Scottish and German research team.

Researchers from the University of Dundee, the Helmholtz Centre for Infection Research and the Max Planck Institute for Plant Breeding Research used a massive sequencing approach called metagenomics to identify the major groups of bacteria that flourish in and around the roots of barley plants.

Their results suggest that the soil surrounding plant roots is a battleground where only certain bacteria can survive, including ‘friendly’ ones that help plants to extract nutrients from soil.

Interactions between soil, soil microbes and plants form a developing and vitally important area of research as the world looks to solve the problems of managing sustainable agricultural productivity to feed an ever growing global population.

“Despite the complexity of organisms in the soil, only a few bacterial families dominate in and around barley roots, and many soil bacteria are excluded,” said Dr Davide Bulgarelli, Royal Society of Edinburgh Research Fellow at the University of Dundee and based at The James Hutton Institute.

“Those groups that do survive are enriched in genes that bacteria use when invading a plant host, when interacting with other microbes, or when defending themselves against viruses, suggesting very active struggles for dominance.

“These new results are an important step towards understanding how we might rationally exploit soil interactions for sustainable intensification of agriculture in the future to ensure food security.”

The results of the study are contained in a manuscript published in the journal Cell Host and Microbe.

Co-author Ruben Garrido-Oter, CEPLAS PhD student from the Max Planck Institute for Plant Breeding Research, said, “Bacterial genes involved in iron mobilisation and sugar transport are also prominent among the groups that survive, hinting at beneficial exchanges of nutrients between plant and microbes.”

The researchers’ hypothesis is that plant-bacterium, bacterium-bacterium and virus-bacterium interactions cooperatively shape the barley microbiota, the microbial population associated with barley roots.

“Several aspects of the plant microbiota remain unknown but our research has uncovered molecular mechanisms which can now be investigated in greater detail,” concluded senior authors Prof Alice McHardy from the Helmholtz Centre for Infection Research and Prof Paul Schulze-Lefert from the Max Planck Institute for Plant Breeding Research.

Useful interactions with soil microbes can bring benefits to crops by increasing yield and protecting them from disease.

Barley is Scotland's most important crop. The barley genome is in the process of being sequenced by a global consortium led by researchers in Dundee, Germany, Australia and the USA and its availability will provide further opportunities for the  Scottish/German group to provide ever greater research possibilities to benefit sustainable crop production.

Roddy Isles
Head of Press
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