Genetically modified (GM) crops have brought various economic benefits but may also have adversely affected soil microorganisms. To examine whether transgenic high-methionine soybean ZD91 alters the bacterial community structure in the rhizosphere, we performed a 2-year follow-up study using the transgenic high-methionine soybean cultivar ZD91 and wild type cultivar ZD. The community composition and the relative abundance of bacteria in rhizosphere soil were determined by sequencing of the 16S rRNA amplicon. Our results indicated that transgenic soybean ZD91 had no significantly effects on rhizosphere bacterial communities. Instead, the plant growth stage and year appeared to have a stronger effect on bacterial communities. Our findings therefore provided reliable scientific evidence for potential commercial cultivation of cultivar ZD91.

The release of genetically modified (GM) crops has potential to alter the bacterial population within rhizosphere. Here, the potential effect of GM maize cv. IE09S034 containing the Cry1Ie toxin gene from Bacillus thuringiensis (Bt) was investigated under the field conditions. The community composition and the relative abundance of the bacteria in rhizosphere soil were estimated by analysing 16S rRNA PCR amplicons. Our results indicated that Bt maize IE09S034 has no significant effects on the rhizosphere bacterial community. Instead, it was found that factors such as plant growth stage and year have a stronger effect on the bacterial population dynamics. Our findings therefore provide reliable evidence supporting the potential commercial cultivation of the cv. IE09S034.

Artificial modification of Bacillus thuringiensis (Bt) proteins can effectively improve their resistance to target pests, but the effect of such modification on the diversity of rhizosphere microorganisms remains unclear. Transgenic maize 2A-7 contains two artificially modified Bt proteins, mCry1Ab and mCry2Ab. These proteins can enter soil and pose a potential threat to soil microbial diversity. To assess their impacts on rhizosphere bacteria communities, the contents of the two Bt proteins and changes in bacterial community diversity in the rhizosphere soils of transgenic maize 2A-7 and its control variety were analyzed at different growth stages in 2020. The results showed that the two Bt proteins were detected at low levels in the rhizosphere soils of 2A-7 plants. No significant differences in soil bacterial diversity were detected between 2A-7 and its control variety at any of the growth stages. Bioinformatics analysis indicated that the growth stage, rather than the cultivar, was the main factor causing changes in bacterial communities. This research provides valuable data for understanding the impact of Bt crops on the soil microbiome, and establishes a theoretical basis for evaluation of their safety.

Transgenic plants may induce shifts in the microbial community composition that in turn alter microbially-mediated nutrient cycling in soil. Studies of how specific microbial groups respond to genetically modified (GM) planting help predict potential impacts upon processes performed by these groups. This study investigated the effect of transgenic high-methionine soybean cv. ZD91 on nitrogen-fixing and ammonia-oxidizing bacterial populations. A difference in nitrogen-fixing or ammonia-oxidizing bacteria community composition was not found, suggesting that cv. ZD91 does not alter the bacterial populations in rhizosphere soil. This study increases our understanding of the potential effect of transgenic soybean on microbial functional groups within soil by suggesting that nitrogen-transforming bacteria may be useful for future investigations on the GM crops impact in the soil ecosystem.