Improving T-DNA Transfer to Tamarix hispida by Adding Chemical Compounds During Agrobacterium tumefaciens Culture

Advancements in plant transformation: from traditional methods to cutting-edge techniques and emerging model species

The ability to efficiently genetically modify plant species is crucial, driving the need for innovative technologies in plant biotechnology. Existing plant genetic transformation systems include Agrobacterium-mediated transformation, biolistics, protoplast-based methods, and nanoparticle techniques. Despite these diverse methods, many species exhibit resistance to transformation, limiting the applicability of most published methods to specific species or genotypes. Tissue culture remains a significant barrier for most species, although other barriers exist. These include the infection and regeneration stages in Agrobacterium, cell death and genomic instability in biolistics, the creation and regeneration of protoplasts for protoplast-based methods, and the difficulty of achieving stable transformation with nanoparticles. To develop species-independent transformation methods, it is essential to address these transformation bottlenecks. This review examines recent advancements in plant biotechnology, highlighting both new and existing techniques that have improved the success rates of plant transformations. Additionally, several newly emerged plant model systems that have benefited from these technological advancements are also discussed.

Establishment of a Genetic Transformation and Gene Editing Method by Floral Dipping in Descurainia sophia

Descurainia sophia L. Webb ex Prantl is used in traditional medicine globally. However, the lack of an efficient and reliable genetic transformation system has seriously limited the investigation of gene function and further utilization of D. sophia. In this study, a highly efficient, time-saving, and cost-effective Agrobacterium tumefaciens-mediated genetic transformation system has been developed in D. sophia. In this method, the transformation was accomplished by simply dipping developing D. sophia inflorescences for 45 s into an Agrobacterium suspension (OD600 = 0.6) containing 5% sucrose and 0.03% (v/v) Silwet L-77. Treated plants were allowed to set seeds which were then plated on a selective medium with hygromycin B (HygB) to screen transformants. Additionally, the CRISPR/Cas9 genomic editing system was validated by targeting phytoene desaturase (PDS) gene using this floral dip method, and mutant plants with the expected albino phenotype could be obtained in 2.5 months. This genetic transformation and targeted editing system will be a valuable tool for routine investigation of gene function and further exploitation in D. sophia.

Agrobacterium tumefaciens-Mediated Plant Transformation: A Review

Agrobacterium tumefaciens-mediated plant transformation is the most dominant technique for the transformation of plants. It is used to transform monocotyledonous and dicotyledonous plants. A. tumefaciens apply for stable and transient transformation, random and targeted integration of foreign genes, as well as genome editing of plants. The Advantages of this method include cheapness, uncomplicated operation, high reproducibility, a low copy number of integrated transgenes, and the possibility of transferring larger DNA fragments. Engineered endonucleases such as CRISPR/Cas9 systems, TALENs, and ZFNs can be delivered with this method. Nowadays, Agrobacterium-mediated transformation is used for the Knock in, Knock down, and Knock out of genes. The transformation effectiveness of this method is not always desirable. Researchers applied various strategies to improve the effectiveness of this method. Here, a general overview of the characteristics and mechanism of gene transfer with Agrobacterium is presented. Advantages, updated data on the factors involved in optimizing this method, and other useful materials that lead to maximum exploitation as well as overcoming obstacles of this method are discussed. Moreover, the application of this method in the generation of genetically edited plants is stated. This review can help researchers to establish a rapid and highly effective Agrobacterium-mediated transformation protocol for any plant species.

Aztreonam is a novel chemical inducer that promotes Agrobacteium transformation and lateral root development in soybean

Agrobacterium-mediated soybean transformation is the simplest method of gene transfer. However, the low transformation due to the intractable nature of soybean genotypes hinders this process. The use of biochemicals (acetosyringone, cinnamic acid, flavonoids, etc.) plays an important role in increasing soybean transformation. These biochemicals induce chemotaxis and virulence gene activation during the infection process. Here we identified a biochemical, aztreonam (a monobactam), for high agrobacterium-mediated transformation in soybean. The soybean explants from three genotypes were inoculated with A. tumefaciens (GV3101) harboring the pMDC32 vector containing hpt or the GmUbi-35S-GUS vector containing the GUS gene during two separate events. High transient GUS expression was obtained during cotyledon explant culture on MS media supplemented with 2.5 mg/L aztreonam. The aztreonam-treated explants showed high efficiency in transient and stable transformation as compared to the untreated control. The transformation of aztreonam-treated explants during seed imbibition resulted in an average of 21.1% as compared to 13.2% in control by using the pMDC32 vector and 28.5 and 20.7% while using the GUS gene cassette, respectively. Based on these findings, the metabolic analysis of the explant after aztreonam treatment was assessed. The high accumulation of flavonoids was identified during an untargeted metabolic analysis. The quantification results showed a significantly high accumulation of the four compounds, i.e., genistein, apigenin, naringenin, and genistin, in cotyledon explants after 18 hours of aztreonam treatment. Alongside this, aztreonam also had some surprising effects on root elongation and lateral root formation when compared to indole-3-butyric acid (IBA). Our findings were limited to soybeans. However, the discovery of aztreonam and its effect on triggering flavonoids could lead to the potential role of aztreonam in the agrobacterium-mediated transformation of different crops.

Genome Editing for Sustainable Crop Improvement and Mitigation of Biotic and Abiotic Stresses

Climate change poses a serious threat to global agricultural activity and food production. Plant genome editing technologies have been widely used to develop crop varieties with superior qualities or can tolerate adverse environmental conditions. Unlike conventional breeding techniques (e.g., selective breeding and mutation breeding), modern genome editing tools offer more targeted and specific alterations of the plant genome and could significantly speed up the progress of developing crops with desired traits, such as higher yield and/or stronger resilience to the changing environment. In this review, we discuss the current development and future applications of genome editing technologies in mitigating the impacts of biotic and abiotic stresses on agriculture. We focus specifically on the CRISPR/Cas system, which has been the center of attention in the last few years as a revolutionary genome-editing tool in various species. We also conducted a bibliographic analysis on CRISPR-related papers published from 2012 to 2021 (10 years) to identify trends and potential in the CRISPR/Cas-related plant research. In addition, this review article outlines the current shortcomings and challenges of employing genome editing technologies in agriculture with notes on future prospective. We believe combining conventional and more innovative technologies in agriculture would be the key to optimizing crop improvement beyond the limitations of traditional agricultural practices.

Genome Editing for Sustainable Crop Improvement and Mitigation of Biotic and Abiotic Stresses

Climate change poses a serious threat to global agricultural activity and food production. Plant genome editing technologies have been widely used to develop crop varieties with superior qualities or can tolerate adverse environmental conditions. Unlike conventional breeding techniques (e.g., selective breeding and mutation breeding), modern genome editing tools offer more targeted and specific alterations of the plant genome and could significantly speed up the progress of developing crops with desired traits, such as higher yield and/or stronger resilience to the changing environment. In this review, we discuss the current development and future applications of genome editing technologies in mitigating the impacts of biotic and abiotic stresses on agriculture. We focus specifically on the CRISPR/Cas system, which has been the center of attention in the last few years as a revolutionary genome-editing tool in various species. We also conducted a bibliographic analysis on CRISPR-related papers published from 2012 to 2021 (10 years) to identify trends and potential in the CRISPR/Cas-related plant research. In addition, this review article outlines the current shortcomings and challenges of employing genome editing technologies in agriculture with notes on future prospective. We believe combining conventional and more innovative technologies in agriculture would be the key to optimizing crop improvement beyond the limitations of traditional agricultural practices.