Plant neighbour type distinctively alters barley root-associated microbiomes under contrasting water stress conditions

Abstract

It is well acknowledged that diversified cropping systems provide ecosystem benefits that promote sustainable crop production. Focal plants growing in diverse communities acquire resilient traits including distinct microbiomes that facilitate nutrient acquisition, disease suppression and resilience against abiotic stresses. Yet, we still have limited knowledge of individual plant neighbour effect on focal host root-associated microbiomes. Here, we examined the effect of plant neighbour on focal barley root microbiome assembly and 16 potential microbial functions under different drought stress scenarios, using bacterial 16S rRNA and fungal ITS amplicon sequencing analysis. We found neighbour type have distinct effects on focal barley microbial diversity and composition under contrasting water stress conditions. Distinct microbial taxa were differentially enriched between barley monocrop and intercrop systems. Distinct plant neighbours promote the enrichment of specific beneficial bacterial genera such as Variovorax, Massilia, Bacillus, Devovsia and Acidovorax in highly water limited than non-limited conditions. Additionally, we found potential microbial functions characterized different intercrop systems under contrasting water stress conditions. Specifically, barley roots from rye neighbour were significantly enriched with several functions associated with the nitrogen cycle, suggesting that rye root traits such as secreted benzoxazinoids could potentially interact with the N-cycling in the soil. These findings deepen our understanding into crop type selection for intercropping systems to promote sustainable crop production