Summary

Differences were detected in the type and diversity of microbes in the area around the roots of Australian barley lines that appeared to be regulated by plant genetics. It is likely that plant exudates or hormones are released that actively recruit specific components of the soil microbiome. Wild barley lines recorded markedly different microbial associations compared to cultivated lines. This finding could indicate an opportunity to modify barley lines to optimise recruitment of soil microbes that provide benefits to plants, like resistance to pathogens or improved nutrient uptake.

Background

Identifying differences in the type and abundance of soil microbes in the area around plant roots and determining if they are influenced by the genetics of the variety could enable growers to choose barley varieties that benefit soil biological health. It would also provide breeders with new molecular tools to develop varieties that improve soil biological health.

The project utilised lines from OzBarley, a public resource that captures the diversity and breeding history of Australian barley. The major Australian barley breeding pedigrees are represented in OzBarley as well as historically significant lines that have contributed to current elite varieties. The information in OzBarley enabled researchers to study lines with known genetic backgrounds and phenotypic characteristics to investigate associations with soil microbial populations.

Research Aims

The core objectives of the project were to:

• Determine whether Australian barley varieties differ in their effects on the diversity of potentially beneficial soil microbes in the field.
• Investigate the genetic control of any observed differences.

In The Field

A range of commercial, international and research barley lines were grown in a field trial at Roseworthy. Soil samples were collected from the roots and the soil microbiome composition analysed using next-generation sequencing. The composition and abundance of the microbiome in the soil directly surrounding each plant was identified. Samples were collected at two time points providing repeated measures of microbiome abundance.

The effect of high yielding varieties RGT-Planet, Spartacus, Oxford, Fathom and Laperouse on microbiome diversity was compared to other lines in the OzBarley collection.

Results

Significant differences in the makeup and diversity of bacteria were found between barley lines. The wild barley lines recorded markedly different microbial associations compared to cultivated barley lines.

Preliminary results found that barley plants in the field actively recruited specific species of bacteria and fungi within their rhizosphere, indicating that the type and variety of microbes living in the soil around the plant roots is directly influenced by the genetics of the plant. It is likely a response to plant root exudates or hormones released into the soil that actively recruit specific components of the microbiome.