Trehalose and the nitrogen fixing nodule symbiosis of legumes : studies on rhizobia deficient in the trehalose-6-phosphate synthase gene "ots"A

The non-reducing disaccharide trehalose (a-D-glucopyranosyl-1,1-a-D-glucopyranoside) is widespread in nature, but is normally not present in higher plants. With respect to plant-microbe interactions, it is interesting that trehalose is regularly found in plant roots interacting with antagonistic fungi, mycorrhizal fungi, and in nitrogen-fixing root nodules, probably as a microbial substance. The impact of trehalose on plant metabolism and its role in nitrogen fixing symbiosis is unclear. This work focuses on the nodule symbiosis. It represents a genetic approach to study the role of trehalose synthesis by the microsymbiont. One pathway for trehalose synthesis is the OtsA/B pathway. Trehalose is synthesized from UDP-glucose and glucose-6-phosphate in a two-step process by the action of trehalose-6-phosphate synthase (OtsA) and trehalose-6-phosphate phosphatase (OtsB). Homologues of the genes coding for these two enzymes in Escherichia coli, otsA and otsB, have been localized on the symbiotic plasmid of Rhizobium sp. NGR234 (pNGR234a). To study the significance of rhizobial trehalose synthesis in free living and symbiotic rhizobia, an Ω-cassette was inserted into the otsA homologue. Phenotypically, the deletion of the rhizobial otsA-homologue strongly reduced trehalose synthesis under microaerobic growth conditions. Thus, there are strong indications that the rhizobial trehalose synthesis induced under hypoxic conditions is directed by the symbiotic plasmid encoded otsA-homologue in conjunction with otsB. The functionality of otsA has therefore indirectly been demonstrated in Rhizobium sp. NGR234, which is the first time in aproteobacteria in general. In addition, the induction of otsA and its homologues by low oxygen conditions has not been previously reported. The natural environment inside nodules is characterized by low oxygen. In contrast, trehalose synthesis under salt stress was not influenced by the mutation of otsA. This indicates that Rhizobium sp. NGR234 exhibits a second trehalose pathway. Activities of maltooligosyltrehalose synthase and maltooligosyl trehalohydrolase (MOS – pathway) had been demonstrated in Rhizobium sp. NGR234 in previous work. To study the role of rhizobial otsA in symbiosis, various host plants were infected with Rhizobium sp. NGRWotsA. In a number of hosts, average nodule size was reduced, nodule number was increased (up to 30 %) and nitrogen fixation was reduced compared to control plants infected with the wildtype strain NGR234. Analysis of the carbohydrate content of these nodules revealed significant increases in the levels of sucrose, hexoses and starch. Thus the deletion of the potential rhizobial otsA-homologue has a severe impact on rhizobium-legume symbiosis, and a signal function of trehalose in carbohydrate partitioning and root nodule development is proposed

Plants Developed by New Genetic Modification Techniques—Comparison of Existing Regulatory Frameworks in the EU and Non-EU Countries

The development of new genetic modification techniques (nGMs), also referred to as “new (breeding) techniques” in other sources, has raised worldwide discussions regarding their regulation. Different existing regulatory frameworks for genetically modified organisms (GMO) cover nGMs to varying degrees. Coverage of nGMs depends mostly on the regulatory trigger. In general two different trigger systems can be distinguished, taking into account either the process applied during development or the characteristics of the resulting product. A key question is whether regulatory frameworks either based on process- or product-oriented triggers are more advantageous for the regulation of nGM applications. We analyzed regulatory frameworks for GMO from different countries covering both trigger systems with a focus on their applicability to plants developed by various nGMs. The study is based on a literature analysis and qualitative interviews with regulatory experts and risk assessors of GMO in the respective countries. The applied principles of risk assessment are very similar in all investigated countries independent of the applied trigger for regulation. Even though the regulatory trigger is either process- or product-oriented, both triggers systems show features of the respective other in practice. In addition our analysis shows that both trigger systems have a number of generic advantages and disadvantages, but neither system can be regarded as superior at a general level. More decisive for the regulation of organisms or products, especially nGM applications, are the variable criteria and exceptions used to implement the triggers in the different regulatory frameworks. There are discussions and consultations in some countries about whether changes in legislation are necessary to establish a desired level of regulation of nGMs. We identified five strategies for countries that desire to regulate nGM applications for biosafety–ranging from applying existing biosafety frameworks without further amendments to establishing new stand-alone legislation. Due to varying degrees of nGM regulation, international harmonization will supposedly not be achieved in the near future. In the context of international trade, transparency of the regulatory status of individual nGM products is a crucial issue. We therefore propose to introduce an international public registry listing all biotechnology products commercially used in agriculture

Structured analysis of broader GMO impacts inspired by technology assessment to inform policy decisions.

If genetically modified organisms (GMOs) are approved in the EU for experimental release or marketing authorization (placing on the market), a risk assessment (RA) is carried out beforehand to determine whether this may be associated with negative effects on human health, nature or the environment. Applications are reviewed by the European Food Safety Authority (EFSA) and the national Competent Authorities of the Member States. However, the potential ramifications of the GMOs that are systematically addressed in the current RA context are limited. Broader consideration can include environmental and health aspects beyond the scope of the statutory RA, as well as societal, ethical and cultural impacts. These other levels of impact may be considered during the comitology process of authorisation, but how this is done is typically not made explicit in a systematic way. However, with the dynamic developments of new kinds of GMOs, these considerations as well as transparency regarding the role of broader considerations in political decision-making become more and more relevant. Against this backdrop, we identified the requirements and suggest the main elements for such a broader assessment. We use insights from the field of Technology Assessment (TA) to explore the requirements for operationalising a rapid but still systematic, transparent and broad case-by-case GMO assessment compatible with the existing legislative framework.publishedVersio

Contribution

Margret Engelhard, Contribution to the discussion Synthetic Biology: Concepts, Values, and Politics, ICI Berlin, 19 September 2014, video recording, mp4, 06:32 <https://doi.org/10.25620/e140919_4

Synthetic biology analysed: tools for discussion and evaluation

Synthetic biology is a dynamic, young, ambitious, attractive, and heterogeneous scientific discipline. It is constantly developing and changing, which makes societal evaluation of this emerging new science a challenging task, prone to misunderstandings. Synthetic biology is difficult to capture, and confusion arises not only regarding which part of synthetic biology the discussion is about, but also with respect to the underlying concepts in use. This book offers a useful toolbox to approach this complex and fragmented field. It provides a biological access to the discussion using a 'layer' model that describes the connectivity of synthetic or semisynthetic organisms and cells to the realm of natural organisms derived by evolution. Instead of directly reviewing the field as a whole, firstly our book addresses the characteristic features of synthetic biology that are relevant to the societal discussion. Some of these features apply only to parts of synthetic biology, whereas others are relevant to synthetic biology as a whole. In the next step, these new features are evaluated with respect to the different areas of synthetic biology. Do we have the right words and categories to talk about these new features? In the third step, traditional concepts like “life” and “artificiality” are scrutinized with regard to their discriminatory power. This approach may help to differentiate the discussion on synthetic biology. Lastly our refined view is utilized for societal evaluation. We have investigated the public views and attitudes to synthetic biology. It also includes the analysis of ethical, risk and legal questions, posed by present and future practices of synthetic biology. This book contains the results of an interdisciplinary research project and presents the authors’ main findings and recommendations. They are addressed to science, industry, politics and the general public interested in this upcoming field of biotechnology

Synthetic Biology:Concepts, Values, and Politics

Synthetic biology employs design and engineering principles to create novel organisms in a much more effective way than earlier biotechnology. One branch of synthetic biology – xenobiology – even develops chemically altered genetic codes and amino acids, which are supposed to effectively isolate the new life from the naturally existing. The synthetic biology research agenda also includes the use of non-living materials to build novel life-forms from scratch. Which concepts of life, which values and worldviews underlie the design and engineering of novel life-forms? What could be the conceptual, ethical, and social implications of a widespread use of synthetic biology? To what ends should synthetic biology be deployed? Consequences and implications of synthetic biology have been researched by philosophers and social scientists alike – often at the request of biologists sensitive to the political and economical need for the public acceptance of their research. Yet, how can research policies help to maintain a plurality of evaluative positions? Join the discussion of what synthetic biology is all about, of its metaphors of creating life, its visions of saving lives, and of the question how social consequences of new techno-scientific fields can or should be evaluated. Arnold Sauter (Deputy Head of the Office of Technology Assessment (TAB) at the German Bundestag and Leader of the TAB project &#8216;Synthetic Biology&#8217;)Inna Kouper (research scientist at Indiana University, Pervasive Technology Institute) Sheref S. Mansy (assistant professor of biochemistry at the Centre for Integrative Biology, University of Trento, working on artificial chemical systems that mimic cellular life) Röbbe Wünschiers (professor of biotechnology at the University of Applied Sciences Mittweida, applying a synthetic biology approach to utilize solar energy for hydrogen gas production with cyanobacteria)Synthetic Biology: Concepts, Values, and Politics, discussion, ICI Berlin, 19 September 2014 <https://doi.org/10.25620/e140919

Am Scheideweg

Der Ökolandbauforscher Urs Niggli verlangt, neue Gentechnikmethoden nicht zu verteufeln, und provoziert damit die eigene Zunft. Auch Techniken wie CRISPR brächten Risiken für Umwelt und Gesundheit, erwidert die Biologin Margret Engelhard und fordert die Prüfung alternativer Wege

Ambivalences of creating life: societal and philosophical dimensions of synthetic biology

"Synthetic biology" is the label of a new technoscientific field with many different facets and agendas. One common aim is to "create life", primarily by using engineering principles to design and modify biological systems for human use. In a wider context, the topic has become one of the big cases in the legitimization processes associated with the political agenda to solve global problems with the aid of (bio-)technological innovation. Conceptual-level and meta-level analyses are needed: we should sort out conceptual ambiguities to agree on what we talk about, and we need to spell out agendas to see the disagreements clearly. The book is based on the interdisciplinary summer school "Analyzing the societal dimensions of synthetic biology", which took place in Berlin in September 2014. The contributions address controversial discussions around the philosophical examination, public perception, moral evaluation and governance of synthetic biology

Where does the EU-path on new genomic techniques lead us?

Recently, the European Commission (EC) published a regulatory proposal on plants generated with new genomic techniques (NGTs) (5 July 2023). According to this proposal, NGT plant applications are categorized into category 1 NGT (NGT1) and category 2 NGT (NGT2) based on their molecular characteristics, which diverges from the current legislation centered around Directive 2001/18/EC. To demonstrate where the path of the proposal leads to in practice, we applied the proposed criteria for categorization to a list of NGT plant applications currently in the commercialization pipeline. Combining literature research and a descriptive statistical approach, we can show that 94% of the plant applications affected by the EC proposal, would be classified as NGT1 and thus would receive market approval without risk assessment, monitoring, and sufficient labeling provisions. The remaining 6% of applications would be classified as NGT2 plants, for which, in deviation from the current regulation, an adapted risk assessment is proposed. Screening of the intended traits in the pipeline highlights that certain NGT1 plants can pose similar environmental risks (e.g., invasiveness) to other genetically modified organisms (GMOs), as defined in Directive 2001/18/EC. For example, NGT1 applications based on RNA interference technology can exhibit insecticidal effects with potential side effects on non-target organisms (i.e., other insects). Our quantitative and case-specific elaboration of how the current EC regulatory proposal would affect the environment, health, and consumer protection will be informative for decision-makers and politicians