Effects of cultivating biotech maize GG2 and glyphosate treatment on the rhizospheric microbial community structure.

In environmental biosafety assessments of glyphosate-tolerant crops, it is essential to evaluate the effects of cultivating these crops and applying glyphosate on the microbial community in the rhizosphere soil, which play a critical role in maintaining soil health, plant growth, and crop productivity. Maize (Zea mays) line GG2 was previously generated by transforming wild-type maize with the gat and gr79-epsps genes, endowing GG2 with both active and passive resistance to glyphosate. However, the ecological risk of introducing these two new glyphosate-tolerance genes into maize, as well as glyphosate treatment, to rhizosphere microorganisms remain unclear. In this study, we used high-throughput sequencing to analyze the diversity and composition of the bacterial and fungal communities in the rhizosphere soil around biotech maize GG2, with (GG2-H) and without glyphosate treatment (GG2-N), compared with the near-isogenic, non-biotech maize line ZD958 at seven stages of growth. The structure and diversity of the bacterial and fungal communities of GG2-H were similar to those of ZD958, whereas glyphosate treatment had temporary effects on bacterial and fungal diversity and richness. The differences in the bacterial and fungal communities were associated with changes in soil properties such as pH, available phosphorus and organic matter, and seasonal changes. These factors, rather than maize lines, made the greatest contributions to the shifts in bacterial and fungal community structure. This study provides a comprehensive analysis of the effects of biotech crop cultivation, glyphosate treatment, soil physicochemical properties of soil, and maize growth stages on soil microbial communities, offering valuable insights for the large-scale adoption of biotech crops in China.

Supplementary information: The online version contains supplementary material available at 10.1007/s42994-025-00205-8.