Effects of field-grown transgenic Cry1Ah1 poplar on the rhizosphere microbiome

Abstract Populus is a genus of globally significant plantation trees used widely in industrial and agricultural production. Poplars are easily damaged by Micromelalopha troglodyta and Hyphantria cunea , resulting in decreasing quality. Because of their strong insect resistance, Bt toxin-encoded Cry genes have been widely adopted in poplar breeding. Therefore, the potential adverse effects of Cry1Ah1- modified (CM) poplars on the ecological environment have been concerned. The Illumina novaseq platform was used to perform high-throughput sequencing . Alpha diversity analyses were performed using the Chao1 index to determine community richness, and the Shannon index analyses were used to determine community richness and evenness. Our analysis of rhizosphere soil chemistry patterns revealed that rhizosphere soil available phosphorus, rhizosphere microbial biomass nitrogen, and rhizosphere phosphorus levels were declined. In contrast, rhizosphere microbial biomass carbon level increased in CM poplar rhizosphere samples. We applied metagenomic sequencing of non-transgenic (NT) and CM poplar rhizosphere samples collected from a natural field; the predominant taxa included Proteobacteria, Acidobacteria, and Actinobacteria. Together, these results showed that the Cry1Ah1 expression has no significant influences on the community composition of rhizosphere microbiomes . Also, the Cry1Ah1 expression in poplars has no notable effects on the relative abundances of most rhizosphere bacteria . In addition, there are no significant adverse effects of CM varieties on most rhizosphere fungal abundances. However, only a few rhizosphere fungal abundances differ in NT and CM varieties.