By Janet Kanters

A new UK study suggests crops consistently select beneficial root microbes based on the functions they provide rather than the type of soil they grow in, a finding researchers say could help shape future crop breeding and microbial product development.

Researchers from Rothamsted Research, CABI, The John Innes Centre, The James Hutton Institute and Scotland’s Rural Agricultural College examined how six major arable crops interact with soil bacteria across different growing environments. The work used soil collected from nine locations across the UK and included wheat, barley, oats, fava beans, oilseed rape and sugar beet.

Using the UK Crop Microbiome Cryobank (UKCMCB), described as the world’s first open crop and soil microbiome resource, the team analyzed more than 24,000 bacterial cultures and 315 soil microbiome libraries.

The researchers found that soil type largely determined which bacterial species were present, but the crops themselves determined what beneficial functions those microbes performed.

“What really stood out was that the soil environment dictates which bacteria are present, but the crop selects bacteria based on what beneficial functions they provide,” said lead author Dr. Rodrigo Taketani of Rothamsted Research. “This tells us that plants are actively selecting microbes for their functional properties – for example, to help with nutrient acquisition or stress tolerance – drawing on locally available bacteria to provide these services.”

The study identified consistent crop-specific patterns across widely different soils and regions.

Sugar beet and oilseed rape attracted microbes linked to drought tolerance, which researchers said may relate to the drier conditions created by the crops’ large tap roots.

Barley attracted microbes that help release zinc from the soil, an important nutrient for plant growth.

Fava beans, meanwhile, attracted fewer microbes involved in breaking down organic nitrogen sources, potentially because the crop already receives nitrogen through its partnership with Rhizobium bacteria.

“These functional differences between crops are remarkably consistent across very different soils and locations,” said co-author Ian Clark of Rothamsted Research. “The fact that we see the same crop-specific patterns whether the soil came from Scotland or Hertfordshire tells us this is a genuine biological selection driven by the plant, not a quirk of any particular soil type.”

The findings could influence how microbial inoculants are developed for agriculture. Rather than relying on a universal product designed to work in all environments, researchers suggest future approaches may need to focus more closely on crop-specific interactions with native soil microbes.

“Due to the high microbial diversity and competition in soil a ‘one size fits all’ approach to microbial inoculation is unlikely to be optimal,” said senior author Dr. Tim Mauchline, also of Rothamsted Research. “A more effective long-term approach may be to breed crops that are better at selecting beneficial native soil microbes, rather than relying on introduced strains that often fail to establish.”

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