Fitness and Ecological Risk of Hybrid Progenies of Wild and Herbicide-Tolerant Soybeans With EPSPS Gene

Subchronic Toxicity Test of Transgenic Herbicide-Tolerant Soybean ZH10-6 in Rats

The herbicide-tolerant soybean ZH10-6 was developed by modifying the Zhonghuang 10 (ZH10) variety with the G2-EPSPS and GAT genes, conferring resistance to glyphosate. This study aimed to assess the potential health effects of ZH10-6 in Sprague-Dawley rats through a 90-day subchronic toxicity test. Seven groups of rats (n = 10/sex/group) were fed a commercial AIN93G diet or diets containing 7.5%, 15%, or 30% ZH10-6 or ZH10 soybeans. General behavior, body weight, and food consumption were monitored weekly. At the end of the study, clinical pathology, including hematology, serum chemistry, urinalysis, and histopathology, were conducted. Throughout the study, all rats remained healthy and showed no abnormal clinical signs. Although some coagulation and serum biochemistry parameters showed statistical differences between groups, all values fell within the historical control ranges and were considered normal biological variability rather than treatment-related effects. The results indicate that ZH10-6 soybean consumption did not cause any adverse health effects in rats. These findings suggest that ZH10-6 is as safe as its nontransgenic parental variety, ZH10, with no evidence of toxicity after 90 days of exposure.

Changes in the Stress Response and Fitness of Hybrids Between Transgenic Soybean and Wild-Type Plants Under Heat Stress

Understanding the ability of hybrids of genetically modified (GM) soybean and wild soybean to survive and reproduce under unfavorable conditions is critical for answering questions regarding risk assessment and the existence of transgenes in the environment. To investigate the effects of high-temperature stress on soybean growth and competitive ability, the GM soybean DBN8002, which expresses the VIP3Aa and PAT proteins, and F2 generations derived from a cross between GM soybean and NJW (wild soybean) were placed in a greenhouse with an elevated temperature (38/32 °C) for 14 days, and the plant agronomic performance and foreign protein levels of hybrid soybean were evaluated to observe their responses to high temperature. The results revealed that the VIP3Aa and PAT protein levels in F2 and GM were not influenced by high-temperature stress. In contrast, the pollen germination, pod number, hundred-seed weight, and seed vigor of the F2 hybrid and parent soybean plants decreased after high-temperature stress. However, except for the number of fully filled seeds per plant, the above parameters of the F2 hybrid were similar to or slightly lower than those of wild soybean, and no significant difference in fitness was observed between the F2 hybrid and wild soybean, indicating that the growth and competitive ability of the hybrid were similar to those of its female parent under heat stress conditions, resulting in the transgenes persisting and spreading within agricultural ecosystems. Our results enhance the understanding of the GM soybean plant's response to heat stress, lay the foundation for breeding heat-resistant soybean varieties, and provide new insights and advanced information on the ecological risks arising from the escape of transgenes.

Insights into the effects of transgenic glyphosate-resistant semiwild soybean on soil microbial diversity

Transgenic soybean [Glycine max(L.) Merrill] currently covers approximately 80% of the global crop area for this species, with the majority of transgenic plants being glyphosate resistant (Roundup Ready, GR or RR). However, there is significant concern regarding the potential effects of GM crops and their byproducts on soil microbial communities. During our research, we discovered a type of semiwild soybean that emerged due to genetic drift at a transgenic test site. Nevertheless, the ecological risk to soil rhizosphere microorganisms associated with planting semiwild soybean following genetic drift remains unclear. Therefore, we conducted a field experiment and collected soil samples at various stages of plant growth. Our results indicate that the species diversity of rhizosphere bacteria in transgenic glyphosate-resistant semiwild soybean was also not significantly different from that observed in other types of soybean. Additionally, Basidiomycota had beneficial effects on rhizosphere fungi during the flowering and maturation stages in transgenic glyphosate-tolerant semiwild soybean. These findings provide valuable insights into how genetic drift in transgenic soybean may impact the soil microenvironment.

Glyphosate resistance and no fitness cost in backcross offspring of wild soybean and transgenic soybean with epsps gene

BACKGROUND

The commercial utilization of genetically modified soybeans has yielded substantial economic advantages. Nevertheless, the genetic drift towards wild soybeans is one of the main ecological risks that needs to be addressed. Previous experiments demonstrated the absence of fitness cost or florescence overlap in hybrid offspring resulting from the crossbreeding of transgenic soybean GTS40-3-2 and Zhengzhou wild soybeans. In this study, hybrid progeny was systematically crossed with wild soybeans to establish a backcross progeny system. This system was employed to evaluate the ecological risk associated with the backcross progeny of transgenic and wild soybeans.

RESULTS

The findings indicated that the offspring from the backcross exhibited glyphosate tolerance. Furthermore, the expression of foreign proteins in the backcross offspring was notably lower than in the transgenic soybean, and there was no significant difference when compared to the hybrid progeny. Parameters such as germination rate, aboveground biomass, pods per plant, full seeds per plant, and 100-grain weight exhibited no significant differences between the negative and positive lines of the backcross progenies, and no fitness cost was identified in comparison to wild soybeans. These results underscore the potential for foreign genes to propagate within other wild soybeans, which requires continuous attention.

CONCLUSIONS

The widespread adoption of genetically modified soybeans has undeniably led to substantial economic gains. However, the research findings emphasize the critical importance of addressing the ecological risks posed by genetic drift towards wild soybeans. The backcross progeny system established in this study indicates that the potential for foreign gene dissemination to wild soybean populations warrants continued attention and mitigation strategies.

In Situ Proteomic Analysis of Herbicide-Resistant Soybean and Hybrid Seeds via Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging

Transgenic soybean is the commercial crop with the largest cultivation area worldwide. During transgenic soybean cultivation, exogenous genes may be transferred to wild relatives through gene flow, posing unpredictable ecological risks. Accordingly, an environmental risk assessment should focus on fitness changes and underlying mechanisms in hybrids between transgenic and wild soybeans (Glycine soja). Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) was used for in situ detection and imaging of protein changes in the seeds of transgenic herbicide-resistant soybean harboring epsps and pat genes, non-transgenic soybean, wild soybean, and their F₂ hybrid. Protein data clearly distinguished wild soybeans, while the F₂ seeds had protein characteristics of both parents and were distinguished from wild soybean seeds. Using UPLC-Q-TOF-MS, 22 differentially expressed proteins (DEPs) were identified, including 13 specific to wild soybean. Sucrose synthase and stress response-related DEPs were differentially expressed in parental and offspring. Differences in these may underpin the greater adaptability of the latter. MSI revealed DEP distribution in transgenic, wild, and F₂ seeds. Identifying DEPs related to fitness may elucidate mechanisms underlying fitness differences among the studied varieties. Our study shows that MALDI-MSI has the potential to become a visual method for transgenic soybean analysis.

Fitness and Rhizobacteria of F2, F3 Hybrids of Herbicide-Tolerant Transgenic Soybean and Wild Soybean

The introduction of herbicide-tolerant (HT) transgenic soybeans (Glycine max (L.) Merr.) into farming systems raises great concern that transgenes may flow to endemic wild soybeans (Glycine soja Sieb. et Zucc.) via pollen, which may increase the ecological risks by increasing the fitness of hybrids under certain conditions and threaten the genetic diversity of wild soybean populations. In order to demonstrate the potential risk of gene flow from the HT soybean to the wild soybean, the fitness of F2 and F3 hybrids obtained from two wild soybean populations (HLJHRB-1, JSCZ) collected from China and the HT soybean was measured under farmland and wasteland soil conditions, as well as with or without weed competition. Compared with their wild progenitors, the F2 and F3 hybrids of HLJHRB-1 displayed a higher emergence rate, higher aboveground dry biomass, more pods and filled-seed plants, as well as better composite fitness under four planting conditions. The F2 and F3 hybrids of JSCZ also displayed a higher emergence rate, higher aboveground dry biomass, more pods, and more filled seeds per plant under mixed planting, whereas these characteristics were lower under pure planting conditions in wasteland and farmland soil. Therefore, the composite fitness of JSCZ hybrids was higher or lower depending on the planting conditions. Furthermore, the soil microbial communities of the F3 of HLJHRB-1, JSCZ, and the wild soybean were investigated with 16S rDNA sequencing, which showed that low alpha diversity of rhizobacteria was relative to high fitness, and Rhizobium played an important role in promoting F3 plant growth.