Field Crop 2024, Vol.7, No.2, 45-57 http://cropscipublisher.com/index.php/fc 49 year 2000 alone, with significant reductions in the use of herbicides and insecticides for crops like soybean, oilseed rape, cotton, and maize (Phipps and Park, 2002). In China, the introduction of Bt maize has mitigated pest pressure without the need for synthetic insecticides, reducing mycotoxin contamination by 85.5%~95.5% and avoiding yield loss by 16.4%~21.3% (Yang et al., 2022). 5.2 Impact on biodiversity and ecosystem health The impact of GM maize on biodiversity and ecosystem health is complex and multifaceted. Studies have shown that the environmental impact of herbicide regimes used with GM herbicide-resistant (GMHR) maize is generally lower than that of non-GMHR maize, primarily due to the lower potential of herbicides like glyphosate and glufosinate-ammonium to contaminate groundwater and their lower acute toxicity to aquatic organisms (Devos et al., 2008). However, the long-term effects on farmland biodiversity, such as shifts in weed communities and losses in food resources and shelter for non-target organisms, remain uncertain (Devos et al., 2008). Additionally, the introduction of GM crops can alter soil microbial communities, although these effects are often variable and transient. For example, while some studies have shown changes in soil metabolomes, the overall impact on rhizosphere bacterial communities appears to be minimal (Figure 2) (Chen et al., 2022). The adoption of GM crops has also been associated with changes in soil food web properties and crop litter decomposition, although these effects are inconsistent and often influenced by environmental factors such as precipitation (Powell et al., 2009). Figure 2 The composition of the rhizosphere bacterial community of insecticidal transgenic and control maize cultivars is estimated by amplicon sequencing (Adopted from Chen et al., 2022) Image caption: (a) Rarefaction curves of the number of OTUs at the 97% sequence similarity of two cultivars at different growth stages. (b) Box plots showing the Good’s coverage for the bacterial community in two cultivars. The relative contribution of top ten bacterial phyla (c) and classes (d) in two cultivars at different growth stages. (e) Differentially altered bacterial genera (relative abundance of 0.1% in at least one treatment) in the transgenic rhizosphere as compared to control maize at different growth stages based on student t-test (* denotes P< .05; and ** denotes P< .01). However, the FDR value for all the genera tested was more than 0.05, indicating that the bacterial composition was not different in transgenic maize and control (Adopted from Chen et al., 2022)
RkJQdWJsaXNoZXIy MjQ4ODY0NQ==