Genetic techniques for plant breeding

Abstract

Food Science and TechnologyVolume 35, Issue 3 p. 52-54 FeaturesFree Access Genetic techniques for plant breeding First published: 16 September 2021 https://doi.org/10.1002/fsat.3503_13.xAboutSectionsPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Wayne Martindale and Craig Duckham explore the barriers to the adoption of new genetic breeding techniques that facilitate the selection of desired traits to improve the quality and quantity of food products. Conventional plant breeding Human societies have been engaged in plant breeding since the beginning of agriculture by selecting plants found to be economically or aesthetically desirable and controlling the mating of selected individuals. Genetic variation has had a major impact on one of the UK's most successful crops, wheat. The straw yield, grain yield and quality of wheat has constantly changed over time to meet the market requirements of consumers as well as to utilise plant nutrients and plant protection applications as efficiently as possible. The Broadbalk Experiment at Rothamsted provides a living lab of these interactions and changes over 150 years. What is striking is that most of these improvements to date have been carried out by observable traits and long-term breeding programmes. We are now on the cusp of a revolution, where observational selection can work with new genetic techniques to provide more targeted outcomes for a 21st century food system1-3. Genetic modification of foods In the 1970s, the development of genetic engineering or genetic modification (GM) methods using recombinant-DNA technology offered the potential to enhance agri-food industry breeding programmes for crops, ornamental plants and animals. The aim was to speed up selection of genetic traits rather than relying on classical breeding programmes that selected from randomised mutations induced using radiation or chemicals, followed by recombination between varieties or breeds. Genetically modified organisms (GMOs) are officially defined in EU legislation as ‘organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating or natural recombination’. We are now on the cusp of a revolution, where observational selection can work with new genetic techniques to provide more targeted outcomes for a 21st century food system. One of the first applications of genetic engineering was the use of transgenic bacteria (Pseudomonas syringae) to reduce ice nucleation on the leaves of frost-susceptible crop plants. This was developed as a product called Frostban but was never marketed because of controversy about its safety4. Since then the most commonly commercialised GMOs have been soybean, maize, cotton and oilseed rape. The greatest commercial impact has been observed for insect resistance and herbicide tolerance, which are single, specific gene transfers that provide plant protection5. The approach can also be used for many other traits, such as enhancing the nutritional value of crops and livestock. These developments have all been achieved by introducing genetic material from unrelated species (transgenics) using Agrobacterium tumefaciens-mediated transformation and biolistic or ‘gene gun’ methods. They require expensive selection programmes, which use herbicide, bioluminescence or antibiotic resistance marker genes to identify the successful transfer of the transgene constructs into new crops or livestock. More recently, new plant breeding techniques, known as gene editing, have been developed, which allow much faster and more precise changes to be made within plant DNA than can be achieved by conventional breeding methods. DNA modifications resulting from gene editing can vary in scale from altering a single base, to inserting or removing one or more genes. Gene editing approaches do not use the marker gene technique, which is the basis of many safety concerns around GMOs, and are being considered for classification as conventional plant breeding techniques that sit outside the current EU GMO legislation. Gene editing uses a group of bacterial enzymes called CRISPR Associated Proteins, one of which (Cas-9) has been demonstrated to identify specific gene sequences in plants and animals that then can be cut, modified or switched on or off (gene silencing) by the Cas-9 enzyme6. There is no transgene construct nor typically a need for a selection marker; the Cas-9 approach uses metabolic means to edit genetic codes, it quite literally provides a metabolic toolbox that can target and modify specific existing genetic sequences. It provides the means to engineer the existing metabolism of crops and livestock with the same precision as that of transgenic methods, without the need to insert foreign DNA. Engaging food stakeholders Opposition to the development of transgenic organisms for use in foods and beverages has created a tortuous path for agricultural R&D pipelines developing new crop varieties, animal breeds and ingredients from microbes. It has also damaged consumer confidence in these GM products, particularly in Europe. Research and development in recent years has led to new crop varieties and livestock breeds using (1) rapid selection technologies and (2) scaling opportunities for market entry for the most beneficial products. However, processors and manufacturers of foods and beverages have often not been fully engaged in exploring the potential of such products within their development programmes. This has resulted in barriers to the adoption of these new breeding techniques in the supply chain and concerns about consumer assurance, which is at the heart of any food supply system. The potential benefits of using genetic techniques for product development are often not widely demonstrated to manufacturers or consumers. As a result, there is a lack of assurance, acceptance and application of ingredients produced by these methods, some of which already have a significant legacy of being used in the brewing and baking industries7. Even so, there are some excellent examples of customer engagement by enzyme and ingredient companies. An important demonstrator has been Novozymes’ use of Life Cycle Assessment to measure the benefits of using biotechnology across several products including nutrients and detergents, where standardised validation is in place for GM products8. However, these initiatives to date have been limited and have not had sufficient traction in research or policy arenas. Golden Rice An example of a missed opportunity to communicate the potential benefits of GM technology to consumers is provided by Golden Rice, which accumulates Provitamin A in the grain as a result of genetic transformation9 and has enormous humanitarian potential in reducing blindness (500,000 children per year) and infant mortality (2-3m deaths per year)10. Although the prototype for Golden Rice was developed some 20 years ago, regulatory requirements and associated costs are still standing in the way of its deployment by farmers. Scientific progress in the public sector has thus become detached from product development and the population at large is not benefiting from that progress9. GM in the food chain An example, which demonstrates the potential extent of the issue, is the presence of GM feed in animal production food chains, even though all livestock products are classed as GM free in Europe. This is because the modified genetic attribute (e.g. for herbicide resistance) is not present in the final food product despite it benefitting significantly from other GM materials in the supply chain. This is an important emergent issue in the food industry with respect to custody of responsible data use associated with products. In the case of herbicide resistance, there have been a number of recent cases at the level of State legislature in the USA that have tested this supply chain custody for GM use in foods11. The custody of supply chain data is now more robust than ever and it has been tested with respect to allergen management, financial irregularities, food fraud and so on. The feed example shows the operating environment has moved on regarding use of GM in foods – without a wider discussion of the potential to realise other opportunities and to consider ongoing challenges related to the use of GM in the food system. We can take this chain of custody further, of course, and for example include assays that utilise GM enzyme technology to measure speciation for authenticity and food fraud analysis. Food production would be seriously disrupted if GM free is a requirement for the whole supply chain. These circumstances could be counterproductive to the point of stifling innovation in the food and beverage industries. GM vs gene editing In the UK and the EU, organisms produced using gene editing techniques are classed as GMOs because the precautionary principle is applied, irrespective of the assessment of safety considerations and measurable impacts on the environment and food safety. In the EU, this position is currently under review because other countries, e.g. Japan12, base their food safety legislation on the safety of the end products of breeding programmes and not by the means the genetic changes are brought about. This is all highly controversial because food producers do not want to arouse the same suspicions about gene edited products as have been associated with transgenic products. It is important to consider CRISPR as a suite of gene editing tools that are relevant for tackling the problems of our future food system. Globalisation has seen the rise of agricultural economies in low and middle income countries that have transformed our worldview of agriculture and food. Climate change, coupled with changes in food production methods and a growing population have brought new issues that necessitate a more circular food economy and net carbon neutral outcomes. The 17 UN Sustainable Development Goals clearly build on eradicating hunger and poverty by aligning to fairness and equity in the use of global resources. They will not be achievable without the successful integration of accessible and assured technologies, such as gene editing, to deliver the necessary advances in food production and processing. Conclusions Food and beverage manufacturers are the ‘missing middle’ between agricultural production and retail/consumers; if they are not engaged in attempts to launch new products or ingredients using new genetic technologies, the opportunities will often be limited in scope. A constructive dialogue is needed to engage food manufacturers and consumers with the potential benefits from these technologies, which can help us to address some of the major challenges for the future food system. Gene editing, in particular, offers a fast, precise technique for making changes to the genome. Changes to European legislation governing gene editing could facilitate the introduction of this technology on a much wider basis, provided that consumers are involved and engaged with the potential benefits. Dr Wayne Martindale, Associate Professor in Food Insights and Sustainability at the National Centre for Food Manufacturing, University of Lincoln. Wayne leads the Food Insights and Sustainability Research agenda at NCFM, working with food and beverage manufacturers to deliver a carbon neutral or carbon zero food system. He's a Fellow of IFST and a science champion for nutrition for the STFC Food+ Network, which supports Early Career Researchers. Email wmartindale@lincoln.ac.uk Craig Duckham, Director of CD R&D Consultancy Services Ltd. Craig provides independent advice to businesses on food ingredients’ technologies. He obtained a PhD in Plant Physiology from the University of Nottingham and is a Fellow of IFST. Craig has over 20 years of technical development experience and has published on topics including plant metabolism, microencapsulation and the alternative uses of Brewer's yeast. 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