MEETING REPORT
Research paper
GM Crops 2:3, 135-137; July–December 2011; © 2011 Landes Bioscience
Bt rice evaluation and deployment strategies P. Manimaran, G. Ramkumar, M. Mohan, S. K. Mangrauthia, A.P. Padmakumari, P. Muthuraman, J.S. Bentur, B.C. Viraktamath and S.M. Balachandran* Directorate of Rice Research; Rajendranagar, Hyderabad, India
Keywords: Bacillus thuringiensis, insect resistance, transgenic rice, evaluation, GM crops
Bacillus thuringiensis (Bt), a gram positive soil bacteria was first identified and named by Japanese Microbiologist Shigetane Ishiwata in 1901. During sporulation Bt produces proteinaceous parasporal crystal proteins called δ-endotoxins, or Cry proteins, which are insecticidal. Numerous Cry proteins have been isolated and characterized from different Bt strains with activity against insects, mites and nematodes. Sprayable formulations containing these Cry proteins as active ingredients have contributed significantly in the field of insect pest management. Since the first cloning of cry genes from Bt,1 scientists have successively demonstrated that plants could be genetically engineered to express these cry genes for the control of dreadful insect pests. Eventually, the first transgenic crop expressing Bt cry1Ac gene in cotton was approved in 1996 for commercial cultivation in the USA to manage bollworms.
© 2012 Landes Bioscience. Genetically modified crops are one of the most innovative approaches in agriculture and have resulted in the large scale adoption of these crops with accumulated hectare from 1996 to 2010 exceeding 1 billion hectares. In 2010, herbicide tolerance deployed in soybean, maize, canola, cotton, sugarbeet and alfalfa, occupied 61% or 89.3 million hectares of the global biotech area of 148 million hectares. In 2010, the stacked double and triple traits occupied a larger area (32.3 million hectares, or 22% of global biotech crop area) than insect resistant trait alone (26.3 million hectares) at 17%. The insect resistance trait products were the fastest growing trait group between 2009 and 2010 at 21% growth, compared with 13% for stacked traits and 7% for herbicide tolerance. In India more than 95% of the cotton planted (9.4 million hectare) is with Bt cry genes to manage bollworms.2 Bt transgenic rice, brinjal and other crops are in the pipeline to seek approval for commercialization. Concerns raised by NGOs have delayed the process of commercialization of these transgenic events. Stem borer resistance breeding has been a difficult endeavor for breeders since there is not a high level of resistance in the rice gene pool and screening for resistance has always been a problem. A number of laboratories developed different local varieties with Bt genes (cry1Ab, cry1Ac, cry1Aa, cry2A, cry1B or a combination of these genes) for resistance against lepidopteran pests. The first field testing of the Bt rice was conducted in China in 1998. However, no Bt rice has been commercialized legally yet. In late 2009, China’s Ministry of Agriculture released biosafety certificates for Bt rice Huahui No. 1 and Bt Shanyou 63 with possible wide scale planting in 2012. Both lines express a cry1Ab/Ac fusion gene. China is now poised to become the first nation in the world to commercialize transgenic rice, which would likely result in a
positive influence on global acceptance and the speed at which biotech food and feed crops are adopted.3 In this context, creating awareness of Bt transgenic technology, its safety, deployment and regulatory issues among the researchers from various field of agriculture is the need of the hour. Hence, Directorate of Rice Research (DRR), a premier rice research institute under the Indian Council of Agricultural Research (ICAR), organized a specific training program on “Bt rice evaluation and deployment strategies” from September 7-27, 2011 with Dr. S.M. Balachandran as the Course Director. Dr. K. Krishnaiah, former Project Director of DRR inaugurated the training program and addressed the trainees about the importance of Bt transgenic rice to manage the lepidopteran target pests and to sustain the rice yield. Dr. Swapan Kumar Datta, Deputy Director General (Crop Science), ICAR, India stressed the importance of GM technology to increase the food production in developing countries including India. He emphasized that such training programs were the need of the hour. The entire training program was structured into four main themes: Basics of Bt and gene cloning, process of transgenic development, field deployment strategies and regulatory/safety issues. Dr. B.C. Viraktamath, Project Director at DRR gave an overview of the rice production in India, its constraints and opportunities, in his inaugural lecture. He pointed to the progress made by China in terms of rice production and productivity, especially on hybrid rice technology. The historical development of Bt and its use in agriculture in terms of sprayable formulations, as well as transgenic expression of its insecticidal genes in various crops, was reviewed in subsequent lectures. The biology and economic importance of various insect pests of rice such as stem borers, leaf folders, leaf plant hoppers, gall midge, etc., were
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*Correspondence to: Sena M. Balachandran; Email:
[email protected] Submitted: 11/14/11; Revised: 12/16/11; Accepted: 12/23/11 http://dx.doi.org/10.4161/gmcr.2.3.19213 www.landesbioscience.com
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covered by the faculty of entomology at DRR. Apart from the entomological aspects, lectures on basic concepts of Bt gene isolation, cloning strategies, construction of plant transformation vectors, plant genetic engineering methods, an RNAi approach for the development of insect resistant transgenic rice and application of transgenic plants in the pharmaceutical industry and agribusiness were delivered by the biotechnology faculty of DRR. Additionally, a lecture on the ecological risk assessment of Bt transgenic crops to non-target pests and beneficial microorganisms covered the procedures for studying the impact of Bt transgenics under the four categories viz., natural enemies of crop pests including predators and parasitoids, pollinators, soil fauna and impact on biodiversity and ecosystem services. The status of risk assessment in already released Bt crops were used to explain the procedures to be used on rice. With respect to the development of Bt transgenics plants, Dr. P. Anandakumar (Director, National Research Centre for Plant Biotechnology, ICAR, India) explained about different insecticidal proteins, different classes of Bt proteins, their mode of action,4 and the current status of their deployment in crop plants in India. He added that the insertion of the native cry gene in the chloroplast genome could have a higher level of expression. Similarly, a high level of expression could also be achieved using synthetic or modified cry genes. Dr. K.R. Kranthi (Director, Central Institute for Cotton Research, India), gave an overview of Bt cotton research, development and field deployment since it was commercialized in 2002 in India. He pointed out some major concerns such as the availability of spurious Bt cotton seeds in the market, monoculturing of Bt cotton hybrids expressing similar cry genes and non-compliance of regulatory issues by farmers and possible development of resistance in the target pest, Helicoverpa armigera. Proteomic analysis of Cry proteins and its binding characteristics to the insect midgut receptor was another interesting topic, addressed by Dr. Raj Bhatnagar from International Centre for Genetic Engineering and Biotechnology (ICGEB, India). He described the mode of action of insecticidal Bt protein through various experimental studies to confirm that the Bt protein was very target-specific and hence safe for non-targeted organisms.5 He further explained that the Bt protein would be inactive in non-targeted organisms due to many factors such as a change in pH, imprecise protease activity, diverged receptor and non-pore formation.6 Following this, Dr. V. Siva Reddy from ICGEB delivered a lecture about the role of mass spectrometry in proteomic analysis of transgenic plants and Cry toxins. He compared the proteome of a GM plant with its non-transgenic counterpart, to elucidate the degree of modification at the proteome level that could provide information about their substantial equivalence at the protein level. In general, the alteration of the proteome in the transgenic counterpart is very small and falls in the range of natural variation. Apart from the deployment of Bt genes in rice and other crops, an introduction of non-Bt genes for insect pest resistant in rice was delivered by Prof. K.V. Rao (Osmania University, India). He discussed the development of transgenic rice with garlic lectin gene (asal)7 and snowdrop lectin gene (gna) 8 against sap sucking
insects such as the brown planthopper (BPH), green leafhopper (GLH) and whitebacked planthopper (WBPH). He concluded that the protein ASAL is more toxic to BPH and GLH insects while GNA showed higher toxicity to WBPH insects; these transgenic lines could serve as a potential genetic resource in recombination-breeding for insect resistance. Dr. H.C. Sharma (ICRISAT, India) listed the availability of candidate genes like protease and amylase inhibitors, chitinase, neurotoxins from mites, scorpions and spiders for their expression in transgenic crops. He emphasized the pyramiding of non-Bt genes with Bt genes for durable wide-spectrum resistance against a wide array of insect pests. Lectures were also delivered from the private sector by Dr. T.M. Manjunath (Former Director, Monsanto Research Centre, India) and Dr. N.P. Sarma (Research Advisor, Kaveri Seeds Pvt Ltd., India). They reiterated the safety issues of Bt to non-target organisms and also addressed insect resistance management (IRM), IPM strategies and the breeding perspectives of transgenic crops and its prospects. After the completion of lectures about development of Bt/non-Bt transgenic crops by various eminent faculties, field evaluation of transgenic rice against yellow stem borer (YSB) and bacterial leaf blight disease was illustrated by Dr. S.M. Balachandran. Intellectual properties right (IPR) issues in biotechnology, protection of rights of farmers and breeders on new plant varieties, trade secrets and patenting biotechnological inventions have were clearly discussed by Dr. R. Kalpana Sastry (National Academy of Agricultural Research Management, India). Finally, to commercialize the transgenic crops, guidelines, rules and regulations framed by various competent authorities including the Institutional Biosafety committee (IBSC), Review Committee on Genetic Manipulation (RCGM), Monitoring cum Evaluation Committee (MEC) and GEAC and their role was explained by Dr. T.V. Ramanaiah (PHI Seeds Ltd, India) and Dr. Balachandran. More than the lectures of theory by these experts, the trainees were provided hands-on experience on isolation of Bt from environment and their identification, separation of crystal proteins, their analysis by SDS-PAGE, PCR analysis of cry genes, cry gene cloning, vector construction, plant tissue culture, genetic transformation, plant genomic DNA isolation, confirmation of transgenic plants by PCR and Southern hybridization, quantification of Cry protein by ELISA, evaluation of Bt transgenics against YSB, leaf folder, pink stem borer and, finally, techniques for evaluation of Bt transgenics/Bt Cry toxins to non-target pests like BPH and natural enemies of rice insect pests. The trainees also visited ICRISAT for exposure to the laboratory facilities and high-end research activities. They visited the platform for translational research on transgenic crops (PTCC, ICRISAT) to gain knowledge on regulatory procedures and mandatory experiments for GM crop approval. PTCC was devised to create a partnership between the public and private sectors to support the conceptualization, development and delivery of agri-biotechnological research products that would ultimately benefit the incomes of Indian farmers. In the context of decreasing arable land and climate change it is quite challenging to feed the burgeoning population of India.
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Concerns regarding the safety of transgenics have been the topic of heated discussion in India and China. However, experience shows that the Indian farmers will adopt Bt products when they perceive the advantages for themselves. The production potential and cost-effectiveness of Bt cotton is the best exemplification. The suicide rate has decreased among cotton farmers and most of the cotton growing areas are occupied with more than 95% with Bt cotton. This will be the case with Bt brinjal and Bt rice in the years to come. When transgenic varieties are ready for release, the pace of their adoption will depend on the advantages conferred by the trait in combination with all others. The bigger the advantage to farmers, the faster and more complete the adoption, all other things being equal. Former Vice-Chancellor, ANGR Agricultural University, Prof. P. Raghava Reddy chaired the valedictory session on the last day of the training. He addressed the advantages of Bt transgenic crops, especially rice, and the environmental benefits derived from the insecticidal specificity of these crops—which unlike synthetic chemical insecticides—kill only target species and reduce chemical insecticide usage. He suggested a possible means for convincing the anti-GMO activists in transgenic food crop deployment, especially of Bt rice in India.
The panel discussion on the last day of the training course suggested the following points for the successful commercialization of Bt transgenic food crops in the future: • improvements in transformation technology; • rigorous biosafety testing at reputed government research laboratories; • multi-location testing of the transgenic lines by ICAR under All India Coordinated Research Project (AICRP); • education of farmers and NGO’s on science and benefits behind GM crops; • simplified approval of GM crops under single umbrella system; • collection and preservation of indigenous germplasm before commercialization of its Bt counterpart; • strict implementation of insect resistance management strategies; • stringent laws to tackle the problems of illegal and spurious Bt seeds in the market; • standardized and rapid detection procedures to monitor GM products; and • stacking of multiple traits for increasing crop production
© 2012 Landes Bioscience. References
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