Clean-gene technology has promise for safe genetically-modified crops |
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An easy and efficient way to develop genetically-modified crops that are 'biosafe' is now available. People worldwide are reluctant to accept genetically-modified foods. They are afraid that they might contain genes, such as those resistant to antibiotics or herbicides, which could be harmful. The clean-gene technology has great potential for Asian and African research programmes that aim to improve rice by genetic methods. It can also be readily used to improve crops grown by poor farmers in China, India and South Africa. Not only important staples, such as maize and wheat, but also orphan crops, such as millet, cowpea, sorghum and many fruits, nuts and vegetables could be improved by this technology. And laboratories in Asia, Africa, the USA and the UK are already using this process. Project Ref: PSP18:
Research Programmes: Plant Science Research Programme. The Rockefeller Foundation (New York, USA) provided additional matching funds to R7548 in order to support the grant and the University fees of the two PhD students involved in this programme. Dr. Abolade Afolabi (from Nigeria) successfully defended his thesis on the development of clean-gene technology in rice at the University of East Anglia (UK) in 2003. Relevant Research Projects: Projects R7548 and R8031. Lead Institute :
Institutional partners:
The RNSS output is a technology called "clean-gene" that allows the production of genetically modified (GM) plants free of selectable marker gene (such as antibiotic or herbicide resistance genes) therefore improving significantly their biosafety. The clean-gene technology was developed over the 2000-2003 period using rice as a model species with high relevance to the developing world. However, it is a generic approach which can be applied to all sexually propagated plant species when undertaking genetic modification. Its principle is to transform plants using two separate vectors, one carrying the transgene of interest (desired additional trait) and the other carrying the selectable marker gene (useful to select the transgenic plants during the transformation process but unwanted afterwards). When the two vectors are delivered using a bacterium called Agrobacterium tumefaciens they integrate, in roughly half of the cases, at different locations in the plant genomes and therefore can be segregated from each other at the next generation. Around two percents of the rice progeny plants produced by clean-gene technology are free of selectable marker gene at the first generation providing an easy and efficient way to produce GM crop plants with improved biosafety. In the past, the presence of selectable marker or reporter genes in transgenic plants represented an important constrain to the dissemination and acceptance of GM crops in the developing and in the developed world. By removing this constrain the output of this programme greatly facilitates the use of transgenic approaches to meet the needs of the poor.
The main commodity in which the approach is relevant to this cluster is rice, however, clean-gene technology is a generic process that can be used during the genetic modification of all sexually propagated plant species. This includes important crops for subsistence farmers such as maize and wheat but also orphan crops such as millet, cowpea, Sorghum as well as sexually propagated tree crops and vegetables. Production Systems:
The output being a technology and not a product, it should be clustered with other outputs from transgenic research programmes aiming at crop improvement in the developing world. This includes outputs from RNRRS sources described "Genetically engineered resistance to rice nematodes" and "Genetically engineered resistance to potato nematodes" as well as R7415 project "Transgenic resistance to Rice Yellow Mottle Virus in rice". This also includes outputs from non-RNRRS sources focusing on GM crop research in National Research Programmes or CGIAR centres such as IRRI, CIMMYT etc. The clean-gene technology can be used directly by many Asian and African research programmes aiming at improving rice through genetic transformation. Great added value could be obtained by using a clean-gene approach to transform locally adapted Asian and African rice cultivars as well as other crops species important for poor and subsistence farmers. The clean-gene technology can be used readily to improve the type of GM crops (such as insect resistant B.t. cotton and B.t. maize) currently grown by poor farmers in China, India and South Africa and therefore can make a direct contribution across poverty groupings. There is also a potential to combine the clean-gene technology outputs with other plant biotechnology and classical breeding approaches such as (i) marker assisted breeding described in PSP22 (focusing on rice) and (ii) participatory breeding. How the outputs were validated: The output provides biosafe technology to the international scientific community interested in using transgenic approaches for crop improvement. Scientists are the primary users and beneficiaries from the clean-gene technology. GM crops with poverty focus traits and available as public goods could have a strong impact on poverty across social groups, gender and income categories. The evidence for demand and the scope of beneficiaries from GM crops can be cross-referenced in PSP19, PSP20 and PSP21 using transgenic approaches to improve nematode resistance in rice, banana and potato. How were the outputs validated? The efficacy of the clean-gene technology has been validated through peer-reviewed publications in international journals: Afolabi SA, Worland B, Snape JW and Vain P (2005) Novel pGreen/pSoup dual-binary vector system in multiple T-DNA co-cultivation as a method of producing marker-free (clean gene) transgenic rice (Oryza sativa L.) plant. African Journal of Biotechnology 4:531-540. Afolabi SA, Worland B, Snape JW and Vain P (2004) A large-scale study of rice plants transformed with different T-DNAs provides new insights into locus composition and T-DNA linkage configurations. Theoretical and Applied Genetics 109: 815-826. In addition clean-gene binary vectors for plant genetic transformation have been distributed free of charge through material transfer agreements (MTAs) to scientists in developing countries (see paragraph below for details). Who validated them? The John Innes Centre was responsible for the development and initial assessment of the clean-gene technology. The University of Leeds quantified the resistance to nematodes of GM rice plants produced using clean-gene technology (PSP19). The referees from international journals validated the scientific data relative to the clean-gene technology. In addition, the 2004 article of Dr. Abolade Afolabi (Nigerian PhD. Student funded by R7548) in Theoretical and Applied Genetics has already been cited six times during the first 10 months of 2006 indicating impact in the scientific community. The scientist that requested the clean-gene vectors for use in their own research programme further validated the technology. This includes scientists from developing countries (Dr. Changyin Wu, China - Dr. Bharat Chattoo, India) but also scientists from developed countries working on research programmes focusing on the developing world (Dr. Amitabh Mohanty, USA). The clean-gene concept can also be used with other binary vector systems and many articles using modified versions of the clean-gene principle have been published. Additional validation The clean-gene technology would not have been developed without the initial work on transformation technology development (PSRP R6121 and R6148) and the ongoing efforts on understanding transgene integration and behaviour in rice (PSRP R8031). This research has been extensively validated through peer-reviewed publications in international journals:
These 12 articles have been cited 341 times in the international literature up to and including October 2006 (ISI web of science), attesting to their high impact. Where the Outputs were Validated:
Who are the Users? How are the outputs currently being used? Clean-gene technology is being used to produce GM plants free of selectable marker genes following the methodology described in scientific publications (Afolabi et al. 2004, 2005) and using the freely available clean-gene binary vectors for plant transformation that we have developed. The clean-gene technology is being integrated into molecular breeding programmes in order to improve GM crop biosafety. This could rapidly benefit the type of GM crops (such as insect resistant B.t. cotton and B.t. maize) currently grown by poor farmers in China, India and South Africa. PSP19 ("Genetically engineered resistance to rice nematodes") provides an example of how clean-gene technology was used to produce GM rice plant resistant to nematodes and free of selectable marker genes. By whom are the outputs are currently being used? The international scientific community is currently
using the outputs. Laboratories in Asia and Africa have been using the
clean-gene technology as demonstrated directly by binary vector requests and
indirectly by literature citations. For example, Dr. Changyin Wu (China), Dr.
Bharat Chattoo (India) and Dr. Amitabh Mohanty (USA) are using our clean-gene
binary vectors for crop transformation. Within the DFID PSRP programmes,
Prof. Howard Atkinson (UK) has used a clean-gene approach to develop biosafe
GM rice with improved resistance to nematodes for the benefit of developing
countries (see PSP19). Where the Outputs have been Used: The principle of the clean-gene approach is being used internationally by the scientific community to develop plant molecular breeding programmes with improved biosafety. The clean-gene vectors are being used the following laboratories:
Scale of current use: The first article on clean-gene technology was published in 2004. The adoption of the technology has taken around one year as demonstrated by the growing number of citations in 2006 and the continuing requests for clean-gene binary vectors for plant transformation since 2005. This dynamic is particularly good for this area of science as it generally takes years to implement changes in crop transformation programmes. Producing GM plants free of selectable marker is likely to become the international standard for both industry and academia and the contribution of the clean-gene technology in this area is likely to greatly increase. PSP0032 research programme has already implemented this strategy to produce clean-gene GM rice plants resistant to nematodes (PSP19). Policy and Institutional Structures, and Key Components for Success: The following factors have contributed to the promotion and adoption of the clean-gene technology:
http://www.research4development.info/caseStudies.asp?ArticleID=176 http://www.dfid-psp.org/Research/CropTrans4.html http://www.jic.ac.uk/staff/philippe-vain/clean-gene.htm
The biotechnological solutions should be answering local needs and have strong biosafety records. This requires an assessment under field conditions in different locations, using different production systems and over several years by National Programmes. Further diffusion to growers via participatory breeding schemes can further contribute to the evaluation and ensure that transgenic plants are fit for purpose. The attitude of local governments towards biotechnologies is also a key factor for success. Lessons Learned and Uptake Pathways Promotion of Outputs: The clean-gene technology is promoted worldwide through peer-reviewed scientific publications and web-based information (see sections B and C of this document). PSP19 ("Genetically engineered resistance to rice nematodes") provides examples of promotion and uptake pathways for GM crops with improved biosafety produced via clean-gene technology. Potential Barriers Preventing Adoption of Outputs: There are no barriers to the adoption of the clean-gene technology as the know-how and transformation vectors are freely available. The clean-gene approach does not bring additional intellectual property right constrains to existing transgenic strategies for crop improvement. However, there are numerous factors that currently prevent the adoption of GM crops into agriculture, particularly regulatory and societal concerns about biosafety. Clean-gene technology aims to improve this situation by better biosefaty. The dissemination and commercialisation on GM crops, food, feed and products in Europe and Africa has been significantly slower than in America and Asia. In many African countries the absence of biosafety regulation and of means to implement them has further prevented the release of GM crops. This also has prevented adequate monitoring of GM plants potentially originating from food aid. Clean-gene technology could help in improving public and regulatory body acceptance by significantly improving the biosafety of GM crops. The end of the DFID PSRP programme in 2006 has stopped the planned testing of nematode resistant GM rice plants produced by clean-gene technology (PSP19 "Genetically engineered resistance to rice nematode") in developing countries. How to Overcome Barriers to Adoption of Outputs: No changes are required for the adoption of the clean-gene technology by the international scientific community. However, many changes are needed to remove or reduce the barriers to the adoption of GM crops in Africa and to a lesser extend in Asia. Helping African countries to develop and implement biosafety regulations is a pre-requisite. Developing transgenic strategies with a strong poverty-focus (i.e. with relevant traits in relevant species) and a public-good approach are also key. Evaluation of the GM crops by participatory breeding after initial testing by National Programmes could help to demonstrate the benefits to poor or subsistence farmers. Maybe more consideration should also be given to the voice of developing world farmers who would like to explore for themselves the potential benefits of biotechnologies to improve their livelihood. The clean-gene technology could promote acceptance of GM crops through the improvement of their biosafety. Lessons Learned: The primary users and beneficiaries of the clean-gene technology are the international scientific community concerned with GM crop improvement. The best ways to optimise use has been through quality and reproducibility of the technology. The PSP19 ("Genetically engineered resistance to rice nematodes") provides examples of the lessons learnt in the most efficient ways to get GM rice produced via clean-gene technology used by the largest number of poor people. Poverty Impact Studies: The output provides enabling technology to the scientific community using genetic modification for crop improvement. Clean-gene transgenic rice plants have been trailed in containment for many years (see PSP19 "Genetically engineered resistance to rice nematodes") but dissemination to developing countries has been stopped at the end of the DFID PSRP programmes in 2006. To date, no GM rice has been released / commercialized worldwide. The impact of GM rice (clean-gene or not) on poverty is therefore difficult to assess post-release. However, insect resistant GM rice is at a pre-commercialisation stage in both Iran (500-1000 farmers) and China (C. James, 2005, Global status of commercialized biotech/GM crop, ISAAA brief 34). The golden rice fortified with pro-vitamin A is also in the pipeline for release in Asia (http://www.goldenrice.org/). Many studies have also analysed in more general terms issues of plant biotechnology and its benefits to the poor:
How the Poor have Benefited (including gender and other poverty groups): To date, no GM rice has been released / commercialized worldwide, therefore only pre-commercialisation data are available for rice. In China, large scale pre-production trials of GM hybrid rice, staring in 2001, showed yield increases of approximately 4 to 8%, plus a saving of 17 kg per hectare in pesticides along with a labour saving of 8 days per hectare resulting in an overall increase in net income per hectare of $80 to $100 (C. James 2005). The socio-economical and environmental impact of other GM crops - such as insect resistant B.t. cotton and B.t. maize - currently commercialised in developing countries - such as China, India or South Africa - has been the subject of many studies (Carl E. Pray et al. 2002 The Plant Journal 31:423-430 ; http://www.isaaa.org/). It is estimated that China has enhanced its farm income from biotech cotton by $4.2 billion in the 1997-2004 period. In 2005, 6.4 million small farmers were growing B.t. cotton in China. However benefits of a different type of B.t. cotton in India have been less clear, highlighting that GM approaches should be tailored to local environments (such as high pest and pathogen pressures), agronomic practices and needs. Direct and Indirect Environmental Benefits: Clean-gene technology significantly improves the biosafety of GM crops by avoiding the presence of selectable marker genes - such as antibiotic or herbicide resistant genes - in genetically engineered plants. The absence of antibiotic resistance genes (coding for kanamycin or hygromycin resistance) eliminates the risk of horizontal gene transfer to bacteria and therefore the risk of building up resistance to antibiotics (with therapeutic value) in micro-organisms. The absence of herbicide resistant genes (when used as a selectable marker gene) eliminates the risk of gene transfer to wild plant relatives and therefore prevents the development of "super-weeds". Producing GM plants free of selectable markers is likely to become the international standard for both industry and academia and the contribution of the clean-gene technology in this area is important. PSP0032 research programme has already implemented this strategy to produce GM rice plants resistant to nematodes and free of antibiotic or herbicide resistant gene (PSP19). Adverse Environmental Impacts: The clean-gene technology has no adverse environmental impact. By avoiding the presence of selectable marker genes in GM crops the clean-gene technology considerably reduces the potential impact of GM crops on the environment and limits the risk assessment to the gene of interest present in the plant. An example of environmental impact of GM rice plants resistant to nematodes and produced by clean-gene technology can be found in PSP19. Coping with the Effects of Climate Change, or Risk from Natural Disasters: The output is an enabling technology to produce GM crops with improved biosafety and therefore, it does not have a direct effect on issues related to climate change. However, GM crops produced by clean-gene technology can make a significant contribution to increase the adaptability of plants to their environment, including climate change. Resistance to biotic (pests and pathogens) and abiotic (environmental) stresses are important avenues for biotechnology research. Insect resistance (using the cry genes from B.t.) is an example of GM trait deployed in Asia and Africa that provides lasting and significant help to cope with pest pressure. PSP19 details how nematode resistant GM rice produced by clean-gene technology can contribute to the capacity of poor people to cope with the effects of climate changes. The ever increasing reliance on plants for food, feed, fibre and fuel in the developing world makes a compelling case to use all the available approaches - conventional or biotechnological - to improve sustainable crop production. Relevant Research Projects,
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