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.

Canna spp., a plant originating from tropical and subtropical areas, has been widely cultivated as an important ornamental plant in the temperate regions of China. In September 2015 and May 2016, symptoms of streak mosaic and severe streak chlorosis were found in the leaves of more than 90% of canna plants in Mount Peach Blossom Park of Zhangqiu, Ji’nan, Shandong province. Eleven symptomatic plants were tested by DAS-ELISA using antibodies for Cucumber mosaic virus (CMV) and Tomato mosaic virus (ToMV) (Agdia, Elkhart, IN) and by PTA-I-ELISA using monoclonal antibody for potyvirus group (Agdia, Elkhart, IN). ELISA results showed that none of these samples were infected by CMV and ToMV, however, the potyvirus tests were positive for all the samples. In order to determine the species of potyvirus infecting the canna plants, total RNA was extracted using a TaKaRa MiniBEST Plant RNA Extraction Kit (Takara, Dalian, China). Then, the cDNA synthesis was performed using an oligodT derived primer (5’-GGTCGACTGCAGGA...

Transgenic maize 2A-7 expressing mCry1Ab and mCry2Ab has excellent resistance to lepidopteran pests. Previous studies have investigated the effects of several Bacillus thuringiensis (Bt) proteins on the soil. However, the effects of artificially modified Bt proteins on soil ecosystems are still unclear. To evaluate the effects of transgenic maize 2A-7 on soil, the physicochemical properties, enzyme activities and functional diversities of the microbial communities in rhizosphere soils from 2A-7 and its near-isogenic non-transgenic control Dongdan 6531 were analyzed at different developmental stages under field conditions. The alteration of six physicochemical properties (pH, total nitrogen, total phosphorus, organic matter, available phosphorus and alkali-hydrolyzed nitrogen) and six functional enzymes (catalase, alkaline phosphatase, sucrase, acid phosphatase, urease and alkaline protease) activities in the rhizosphere soils between the two maize cultivars were drastically correlated with plant growth stage, but not affected by the artificially modified Bt transgenes. An analysis of time-course Biolog data revealed that the functional diversity of microbial communities in the rhizosphere soil of 2A-7 and its control were similar at each developmental stage. The results suggest that transgenic maize 2A-7 has no significant impact on the soil ecosystem and provide valuable information on scientific safety assessments of 2A-7 and its commercial applications.

Iris tectorum Maxim, an Iridaceae family perennial monocotyledon plant, is a popular ornamental flower all over the world. In July 2015, a large number of iris plants showing virus-like symptoms, such as streak mosaic, severe chlorosis and eventually streak necrotic, were collected from the green belts and gardens of Tai’an, Shandong province, China. Total RNA was extracted from six samples using a plant RNA extraction kit (Takara, Dalian, China). Reverse transcription PCR was performed with a one-Step RT-PCR kit (Takara, Dalian, China) using the degenerate primers designed for amplification regions from NIb to 3’ UTR of potyviruses (NIb-F 5’-GGNAAYAAYAGYGGNCARCC-3’ and M4-T 5’-GTTTTCCCAGTCACGACT15-3’, ~1.7 kb) (Chen et al. 2001), MP to 3’ UTR of tobamoviruses (Tom-F 5’-GTYGTTGATGAGTTCRTGGA-3’ and Tom-R 5’-ATTTAAGTGGASGGAAAAVCACT-3’, ~800 bp) (Letschert et al. 2002) and CP of Cucumber mosaic virus (CMV, CMV CP-F 5’-ATGGACAAATCTGGATCAAC-3’ and CMV CP-R 5’-TCAGACTGGGAGCACCCCAG-3’, ~650 bp). PCR results show...

With the development of commercialized planting of genetically modified crops, their ecological security risks remain a key topic of public concern. Insect-resistant genetically modified maize, Ruifeng125, which expresses a fusion Bt protein (Cry1Ab-Cry2Aj), has obtained the application safety certificate issued by the Chinese government. To determine the effects of Ruifeng125 on the diversity and dynamics of bacterial communities, the accumulation and degradation pattern of the fusion Bt protein in the rhizosphere soil of transgenic maize were detected. Results showed that the contents of Bt protein varied significantly at different developmental stages, but after straw was returned to the field, over 97% of Bt proteins were degraded quickly at the early stages (≤10 d) and then they were degraded at a relatively slow rate. In addition, the variations in bacterial community diversity in the rhizosphere soil were detected by 16S ribosomal RNA (Rrna) high-throughput sequencing technology. A total of 44 phyla, 435 families, and 842 genera were obtained by 16S rRNA sequencing, among which Proteobacteria, Actinobacia, Acidobacter Acidobacterium, and Chloroflexi were the dominant taxa. At the same developmental stage, no significant differences in soil bacterial diversity were detected between Ruifeng125 and its non-transgenic control variety. Further analysis revealed that developmental stage, rather than the transgenic event, made the greatest contribution to the changes in soil microbial diversity. This research provides important information for evaluating the impacts of Bt crops on the soil microbiome and establishes a theoretical foundation for their environmental safety assessment.

The consequences of stacking multiple insect-resistance and herbicide-tolerance genes, particularly across the entire plant life cycle, remain inadequately understood. This study investigated the impact of stacked-trait transgenic soybean (expressing cry1Ac, vip3Aa19, mOsPPO2, and pat genes) on rhizosphere microbial communities across five growth stages (pre-sowing, V3, R3, R5, R8). Using 16S rRNA and ITS sequencing, we compared the rhizosphere microbiome of the transgenic modified soybean (GMO) with its non-transgenic control check (CK). Results showed transient but significant shifts in soil properties (e.g., available nitrogen) and microbial beta-diversity during the V3 stages. However, plant developmental stage was the predominant factor shaping microbial succession, with its effect outweighing that of the transgene. No persistent changes in microbial alpha-diversity were observed. We conclude that the influence of this stacked-trait soybean on the rhizosphere is growth-stage-specific and represents a minor, recoverable perturbation rather than a sustained ecological impact. These findings contribute to the ecological safety assessment of multi-gene transgenic crops.