Taxonomic and functional changes in wheat rhizosphere microbiome caused by imidazoline-based herbicide and genetic modification

Abstract

Genetically modified (GM) crop cultivation has received a lot of attention in recent years due to the substantial public debate. Consequently, an in-depth investigation of excessively used GM herbicide-tolerant crops is a vital step for the biosafety of genetically modified plants. Several studies have been conducted to study the impact of transgenic GM crops on soil microbial composition; however, research into the effects of non-transgenic GM crops is inadequate. In the current work, high-throughput sequencing was used to evaluate the impact of the acetolactate synthase (ALS)-mutant (WK170B), its control (YN19B), and the imazamox (IM) herbicide on the wheat rhizobiome. Under normal growth conditions, our work revealed a minimal impact of ALS-mutant WK170B on the rhizosphere microbiome compared to the control YN10B, except for some cyanobacterial microorganisms that showed a significant increase in abundance. This suggests that the gene mutation could potentially have a beneficial impact on the bacterial communities present in the rhizosphere. Following IM exposure, taxonomic analysis revealed a significant reduction in the relative abundance of Ralstonia pickettii and an unidentified member of the genus Ancylothrix 8 PC. Analyses of both alpha and beta diversity revealed a statistically significant increase in both microbial richness and species diversity. IM-induced relative abundance modulation was also evident through Linear discriminant analysis Effect Size (LEfSe), MetaStat, and heatmap analyses. The SIMPER analysis revealed that the microbial taxa Massilia, Limnobacter, Hydrogenophaga, Ralstonia, Nitrospira, and Ramlibacter exhibited the highest vulnerability to IM exposure. The functional attributes analysis revealed that the relative abundance of genes associated with the extracellular matrix-receptor interaction, which is responsible for structural support and stress response, increased significantly following IM exposure. Collectively, our study identifies key microbial taxa in the wheat rhizobiome that are sensitive to IM herbicides and provides a foundation for assessing the environmental risks associated with IM herbicide use.