Overview of Biotechnology-Derived Herbicide Tolerance and Insect Resistance Traits in Plant Agriculture

Safety Assessment of the CP4 EPSPS and NPTII Proteins in Eucalyptus

Glyphosate herbicide treatment is essential to sustainable Eucalyptus plantation management in Brazil. Eucalyptus is highly sensitive to glyphosate, and Suzano/FuturaGene has genetically modified eucalyptus to tolerate glyphosate, with the aim of both protecting eucalyptus trees from glyphosate application damage and improving weed management. This study presents the biosafety results of the glyphosate-tolerant eucalyptus event 751K032, which expresses the selection marker neomycin phosphotransferase II (NPTII) enzyme and CP4-EPSPS, a glyphosate-tolerant variant of plant 5-enolpyruvyl-shikimate-3-phosphate synthase enzyme. The transgenic genetically modified (GM) event 751K032 behaved in the plantations like conventional non-transgenic eucalyptus clone, FGN-K, and had no effects on arthropods and soil microorganisms. The engineered NPTII and CP4 EPSPS proteins were heat-labile, readily digestible, and according to the bioinformatics analyses, unlikely to cause an allergenic or toxic reaction in humans or animals. This assessment of the biosafety of the glyphosate-tolerant eucalyptus event 751K032 concludes that it is safe to be used for wood production.

Triple-transgenic soybean in conjunction with glyphosate drive patterns in the rhizosphere microbial community assembly

Plant roots continuously influence the rhizosphere, which also serves as a recruitment site for microorganisms with desirable functions. The development of genetically engineered (GE) crop varieties has offered unparalleled yield advantages. However, in-depth research on the effects of GE crops on the rhizosphere microbiome is currently insufficient. We used a triple-transgenic soybean cultivar (JD606) that is resistant to insects, glyphosate, and drought, along with its control, ZP661, and JD606 treated with glyphosate (JD606G). Using 16S and ITS rDNA sequencing, their effects on the taxonomy and function of the bacterial and fungal communities in the rhizosphere, surrounding, and bulk soil compartment niches were determined. Alpha diversity demonstrated a strong influence of JD606 and JD606G on bacterial Shannon diversity. Both treatments significantly altered the soil's pH and nitrogen content. Beta diversity identified the soil compartment niche as a key factor with a significant probability of influencing the bacterial and fungal communities associated with soybeans. Further analysis showed that the rhizosphere effect had a considerable impact on bacterial communities in JD606 and JD606G soils but not on fungal communities. Microbacterium, Bradyrhizobium, and Chryseobacterium were found as key rhizobacterial nodes. In addition, the LEfSe analysis identified biomarker taxa with plant-beneficial attributes, demonstrating rhizosphere-driven microbial recruitment. FUNGuild, Bugbase, and FAPROTAX functional predictions showed that ZP661 soils had more plant pathogen-associated microbes, while JD606 and JD606G soils had more stress-tolerance, nitrogen, and carbon cycle-related microbes. Bacterial rhizosphere networks had more intricate topologies than fungal networks. Furthermore, correlation analysis revealed that the bacteria and fungi with higher abundances exhibited varying degrees of positive and negative correlations. Our findings shed new light on the niche partitioning of bacterial and fungal communities in soil. It also indicates that following triple-transgenic soybean cultivation and glyphosate application, plant roots recruit microbes with beneficial taxonomic and functional traits in the rhizosphere.

Genetic modification strategies for enhancing plant resilience to abiotic stresses in the context of climate change

Enhancing the resilience of plants to abiotic stresses, such as drought, salinity, heat, and cold, is crucial for ensuring global food security challenge in the context of climate change. The adverse effects of climate change, characterized by rising temperatures, shifting rainfall patterns, and increased frequency of extreme weather events, pose significant threats to agricultural systems worldwide. Genetic modification strategies offer promising approaches to develop crops with improved abiotic stress tolerance. This review article provides a comprehensive overview of various genetic modification techniques employed to enhance plant resilience. These strategies include the introduction of stress-responsive genes, transcription factors, and regulatory elements to enhance stress signaling pathways. Additionally, the manipulation of hormone signaling pathways, osmoprotectant accumulation, and antioxidant defense mechanisms is discussed. The use of genome editing tools, such as CRISPR-Cas9, for precise modification of target genes related to stress tolerance is also explored. Furthermore, the challenges and future prospects of genetic modification for abiotic stress tolerance are highlighted. Understanding and harnessing the potential of genetic modification strategies can contribute to the development of resilient crop varieties capable of withstanding adverse environmental conditions caused by climate change, thereby ensuring sustainable agricultural productivity and food security.

Sensibility, multiple tolerance and degradation capacity of forest species to sequential contamination of herbicides in groundwaters

Herbicides have already reported environmental contamination in several countries with intense agricultural activity. The transport of these molecules due to leaching and surface runoff has frequently caused contamination of rivers, groundwater and soil in non-agricultural areas. Thereby, we propose to investigate the sensitivity and phytoremediation capacity of 5 native Cerrado species to sequential exposure to 2,4-D, atrazine, diuron and hexazinone. We hypothesized that species have different sensitivity levels to sequential exposure to these herbicides absorbed from contaminated simulated groundwater model. The objectives of this work were: i) to determine the sensitivity of native cerrado species by sequential exposure to 2,4-D, atrazine, diuron and hexazinone via contaminated simulated groundwater model; ii) to evaluate the presence and degradation capacity of these herbicides in the soil and water leached by tolerant species. Some species showed high phytoremediation potential for groundwater already contaminated with 2,4-D, atrazine, diuron and hexazinone. S. macranthera and C. antiphilitica are tolerant and reduce the concentration of herbicides in simulated groundwater model. Among these species, C. antiphilitica reduces the concentration of all herbicides, suggesting greater adaptability to compose decontamination strategies in areas close to agricultural systems that use 2,4-D herbicides, atrazine, diuron and hexazinone. Also, our results show that herbicides can act as a selection factor for Cerrado forest species, however, two species can mitigate the effects of contamination due to their ability to degrade herbicides.

Comparison of in Vitro and in Planta Toxicity of Vip3A for Lepidopteran Herbivores

Agricultural pest infestation is as old as domestication of food crops and contributes a major share to the cost of crop production. In a transgenic pest control approach, plant production of Vip3A, an insecticidal protein from Bacillus thuringiensis, is effective against lepidopteran pests. A synthetic Vip3A gene was evaluated for efficacy against Spodoptera litura Fabricius (Lepidoptera: Noctuidae; cotton leafworm), Spodoptera exigua Hübner (Lepidoptera: Noctuidae; beet armyworm), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae; fall armyworm), Helicoverpa armigera Hübner (Lepidoptera: Noctuidae; cotton bollworm), Helicoverpa zea Boddie (Lepidoptera: Noctuidae; corn earworm), Heliothis virescens Fabricius (Lepidoptera: Noctuidae; tobacco budworm), and Manduca sexta L. (Lepidoptera: Sphingidae; tobacco hornworm) in tobacco. In artificial diet assays, the concentration required to achieve 50% mortality was highest for H. zea followed by H. virescens > S. exigua > H. armigera > M. sexta > S. frugiperda > S. litura. By contrast, in bioassays with detached leaves from Vip3A transgenic tobacco, the time until 50% lethality was M. sexta > H. virescens > S. litura > H. zea > H. armigera > S. exigua. There was no significant correlation between the artificial diet and transgenic plant bioassay results. Notably, the two insect species that are best-adapted for growth on tobacco, M. sexta and H. virescens, showed the greatest time to 50% mortality on Vip3A-transgenic tobacco. Together, our results suggest that artificial diet assays may be a poor predictor of Vip3A efficacy in transgenic plants, lepidopteran species vary in their sensitivity to Vip3A in diet-dependent manner, and host plant adaptation of the targeted herbivores should be considered when designing transgenic plants for pest control.

The bacterial potassium transporter gene MbtrkH improves K+ uptake in yeast and tobacco

K+ is an essential nutrient for plant growth and is responsible for many important physiological processes. K+ deficiency leads to crop yield losses, and overexpression of K+ transporter genes has been proven to be an effective way to resolve this problem. However, current research on the overexpression of K+ transporter genes is limited to plant sources. TrkH is a bacterial K+ transporter whose function generally depends on the regulation of TrkA. To date, whether TrkH can improve K+ uptake in eukaryotic organisms is still unknown. In this study, a novel MbtrkH gene was cloned from marine microbial metagenomic DNA. Functional complementation and K+-depletion analyses revealed that MbTrkH functions in K+ uptake in the K+-deficient yeast strain CY162. Moreover, K+-depletion assays revealed that MbtrkH overexpression improves plant K+ uptake. K+ hydroponic culture experiments showed that, compared with WT tobacco lines, MbtrkH transgenic tobacco lines had significantly greater fresh weights, dry weights and K+ contents. These results indicate that MbTrkH promotes K+ uptake independently of TrkA in eukaryotes and provide a new strategy for improving K+-use efficiency in plants.