Reasons and riddance of Agrobacterium tumefaciens overgrowth in plant transformation

Agrobacterium-Mediated Transformation for the Development of Transgenic Crops; Present and Future Prospects

Plant transformation based on Agrobacterium-mediated transformation is a technique that mimics the natural agrobacterium system for gene(s) introduction into crops. Through this technique, various crop species have been improved/modified for different trait/s, showing a successful genetic transformation so far. This technique has many advantages over other transformation methods such as stable integration of transgene, cost effective. However, there are many limitations of this technology such as mostly the crops are recalcitrant to agrobacterium, low transformation efficiency, transgene integration as well as off targets. So, it's very important to explore the major limitations and possible solutions for Agrobacterium-mediated transformation in order to increase its genetic transformation efficiency. Therefore, the present review article gives a comprehensive study how the transgenic crops are developed using Agrobacterium-mediated transformation, crops that have already been modified through this method, and risks associated with transgenic plants based on Agrobacterium-mediated transformation. Moreover, the challenges and problems associated with Agrobacterium-mediated transformation and how those problems can be solved in future for a successful genetic transformation of crops using modern biotechnology techniques such as CRISPR/Cas9 systems. The present review article will be really helpful for the audience those working on Genome editing of crops using Agrobacterium-mediated transformation and will opens many ways for future plant genetic transformation.

A comprehensive review of in planta stable transformation strategies

Plant transformation remains a major bottleneck to the improvement of plant science, both on fundamental and practical levels. The recalcitrant nature of most commercial and minor crops to genetic transformation slows scientific progress for a large range of crops that are essential for food security on a global scale. Over the years, novel stable transformation strategies loosely grouped under the term "in planta" have been proposed and validated in a large number of model (e.g. Arabidopsis and rice), major (e.g. wheat and soybean) and minor (e.g. chickpea and lablab bean) species. The in planta approach is revolutionary as it is considered genotype-independent, technically simple (i.e. devoid of or with minimal tissue culture steps), affordable, and easy to implement in a broad range of experimental settings. In this article, we reviewed and categorized over 300 research articles, patents, theses, and videos demonstrating the applicability of different in planta transformation strategies in 105 different genera across 139 plant species. To support this review process, we propose a classification system for the in planta techniques based on five categories and a new nomenclature for more than 30 different in planta techniques. In complement to this, we clarified some grey areas regarding the in planta conceptual framework and provided insights regarding the past, current, and future scientific impacts of these techniques. To support the diffusion of this concept across the community, this review article will serve as an introductory point for an online compendium about in planta transformation strategies that will be available to all scientists. By expanding our knowledge about in planta transformation, we can find innovative approaches to unlock the full potential of plants, support the growth of scientific knowledge, and stimulate an equitable development of plant research in all countries and institutions.

Analysis of Marchantia polymorpha-microorganism interactions: basis for understanding plant-microbe and plant-pathogen interactions

Marchantia polymorpha is a bryophyte gaining significance as a model plant in evolutionary studies in recent years. This is attributed to its small-sequenced genome, standardized transformation methodology, global distribution, and easy and rapid in vitro culturing. As an evolutionary model, M. polymorpha contributes to our understanding of the evolution of plant defensive responses and the associated hormonal signaling pathways. Through its interaction with microorganisms, M. polymorpha serves as a valuable source of knowledge, yielding insights into new microbial species and bioactive compounds. Bibliographic analysis involved collecting, reading, and categorizing documents obtained from the Scopus and Web of Science databases using different search terms. The review was based on 30 articles published between 1995 and 2023, with Japanese and Spanish authors emerging as the most prolific contributors in this field. These articles have been grouped into four main themes: antimicrobial metabolites produced by M. polymorpha; identification and characterization of epiphytic, endophytic, and pathogenic microorganisms; molecular studies of the direct interaction between M. polymorpha and microorganisms; and plant transformation using bacterial vectors. This review highlights the key findings from these articles and identifies potential future research directions.

Establishment of a Rapid and Effective Agrobacterium-Mediated Genetic Transformation System of Oxalis triangularis 'Purpurea'

Oxalis triangularis 'Purpurea' has significant ornamental value in landscaping. There is a critical necessity to elucidate the gene functions of O. triangularis 'Purpurea' and dissect the molecular mechanisms governing key ornamental traits. However, a reliable genetic transformation method remains elusive. In this study, our investigation revealed that various transformation parameters, including recipient material (petioles), pre-culture time (2-5 days), acetosyringone (AS) concentration (100-400 μM), Agrobacterium concentrations (OD600 = 0.4-1.0), infection time (5-20 min), and co-culture time (2-5 days), significantly impacted the stable genetic transformation in O. triangular 'Purpurea'. Notably, the highest genetic transformation rate was achieved from the leaf discs pre-cultured for 3 days, treated with 200 μM AS infected with Agrobacterium for 11 min at OD600 of 0.6, and subsequently co-cultured for 3 days. This treatment resulted in a genetic transformation efficiency of 9.88%, and it only took 79 days to produce transgenic plants. Our transformation protocol offers advantages of speed, efficiency, and simplicity, which will greatly facilitate genetic transformation for O. triangular 'Purpurea' and gene function studies.

An Efficient Transformation System for Fast Production of VcCHS Transgenic Blueberry Callus and Its Expressional Analysis

The Agrobacterium tumefaciens-mediated transformation for blueberries remains less efficient than is desirable. A new leaf callus regeneration and genetic transformation system was investigated in blueberries in this study. The leaf explants of cv. 'Legacy' and 'Northland' were used to establish the stable callus induction system when placed on the woody plant medium (WPM) supplemented with 1.0 mg·L-1 2, 4-D, 0.4 mg·L-1 6-BA for 30 d; then, the callus was sub-cultured in the proliferation medium supplemented with 1.5 mg·L-1 2, 4-D, 0.4 mg·L-1 6-BA in the darkness at 25 °C every 30 days. The co-cultivation of callus with A. tumefaciens was operated on WPM plus 100 μM acetosyringone for 4 days; then, the transferred callus was grown in WPM supplemented with 1.5 mg·L-1 2,4-D, 0.4 mg·L-1 6-BA, 50 mg·L-1 hygromycin, and 200 mg·L-1 cefotaxime. The VcCHS transgenic blueberry callus with both GFP signal and Hyg resistance was obtained from the transformed callus of cv. 'Northland'. The rate of GFP signal detected in the transformed callus was as high as 49.02%, which was consistent with the PCR assay. Collectively, this study provides a highly efficient genetic transformation system in blueberry callus and a powerful approach for the molecular breeding of blueberries.

Research Progress of Nucleic Acid Detection Technology for Genetically Modified Maize

Genetically modified (GM) maize is one of the earliest GM crops to have achieved large-scale commercial cultivation globally, and it is of great significance to excel in the development and implementation of safety policy regarding GM, and in its technical oversight. This article describes the general situation regarding genetically modified maize, including its varieties, applications, relevant laws and regulations, and so on. From a technical point of view, we summarize and critically analyze the existing methods for detecting nucleic acid levels in genetically modified maize. The nucleic acid extraction technology used for maize is explained, and the introduction of traditional detection techniques, which cover variable-temperature and isothermal amplification detection technology and gene chip technology, applications in maize are described. Moreover, new technologies are proposed, with special attention paid to nucleic acid detection methods using sensors. Finally, we review the current limitations and challenges of GM maize nucleic acid testing and share our vision for the future direction of this field.