- Email: [email protected]
Wanted: misinterpreted science
trends in plant science Headlines Benefit of Bt corn hybrids Transgenic corn hybrids that express the Bacillus thuringiensis (Bt) toxin to control the European corn borer, usually have reduced Fusarium ear rot, and consequently, lower fumonisin concentrations. In general, mycotoxin build-up is directly related to certain fungal plant diseases, which can be increased by insect damage in crops. Kernel rot caused by the fungus Aspergillus is also associated with insect damage to ears. Several species of this fungus produce the most notorious mycotoxins found in corn, the aflatoxins. ‘Debate surrounding the use of genetically modified crops should be based on risk–benefit assessment, including environmental impacts, live-stock impacts, and potential human health threats…Consumers and regulatory agencies should consider the food safety and environmental implications of Bt corn when making decisions about its use.’ American Phytopathological Society (http://www.scisoc.org).
Saving crop diversity The US Agricultural Research Service (ARS) maintains a network of 26 repositories nationwide that preserve and regenerate germplasm seed and other reproductive tissues of crops and their wild relatives. The system houses .400 000 accessions comprising .10 000 species. An accession is a genetically distinct group of plants, such as a crop variety or a wild subspecies. More than 200 organic seed farmers are growing 800 breeding lines of traditional crop plants provided by the National Plant Germplasm System. The Farmer Cooperative Genome Project, based in Junction City, OR, USA, was started in 1998 with a USDA Fund for Rural America grant. More details on the project appear on the web (http://www.ars.usda.gov/is/AR/archive/ oct99/seed1099.htm).
PTGS in plants Post-transcriptional gene silencing (PTGS) is a nucleotide sequence-specific defense mechanism that can target both cellular and viral mRNAs. A recent study analyzed three types of transgene-induced PTGS and one example of virus-induced PTGS in plants. In each case, antisense RNA complementary to the targeted mRNA was detected. These RNA molecules were of a uniform length, estimated at 25 nucleotides. Their accumulation required either transgene sense transcription or RNA virus replication. Thus, the 25-nucleotide antisense RNA is probably synthesized from an RNA template and might represent the specificity determinant of PTGS. Science (1999) 286, 950–952.
Compromised resistance in saponin-deficient plants Saponins are glycosylated plant secondary metabolites with potent antifungal properties that occur in many major food crops. The isolation of mutants defective in saponin biosynthesis represents a powerful strategy for evaluating the importance of these compounds in plant defense. A recent study has confirmed that saponin-deficient mutants of a diploid oat species, Avena strigosa, are indeed compromised in their resistance to a variety of fungal pathogens. Proc. Natl. Acad. Sci. U. S. A. (1999) 96, 12923–12928.
Health benefits of GM beet A genetically modified (GM) beet developed by Novartis uses genes from Jerusalem artichokes (Helianthus tuberosus) to convert almost all the sucrose in the beet root into fructans. These sweeteners cannot be digested but help to cultivate ‘friendly’ bacteria in the gut and fight cholesterol. ‘We need to show that gene technology can benefit consumers’ (Paul Tenning, Regulatory Affairs manager at Novartis Seeds AB, Sweden). The modified beet requires less spraying with chemical herbicides, so the environmental benefit should also be attractive to the consumers. However, US food and soft drinks exporters are concerned that they might have difficulty selling products in Europe that have been sweetened by GM sugar.
40% more GM crops in 1999 In 1999, the amount of land planted with genetically modified (GM) crops around the world is expected to have increased by .40%. Significant increases were in China, Argentina, Canada and South Africa. Three countries, Portugal, Romania and Ukraine, had commercial plantings for the first time in 1999.
USDA estimate of GM crops According to the US Agriculture Dept more than half of the US soybean crop this year was planted with genetically modified (GM) seeds, and corn and cotton were not far behind. The new USDA data, collected from interviews with farmers during the summer, were in line with seed companies’ estimates of how much land has been planted with bioengineered crops. Thirty percent of US corn and ~27% of US cotton planted in 1999 were of the Bt variety (which express Bacillus thuringiensis toxins), some 57% of US soybeans were planted with herbicide-resistant varieties, most of them Roundup Ready (Monsanto).
Milk as a fungicide The mould, Sphaerotheca fuliginea, appears as a powdery white growth on the leaves of cucumbers and zucchini (Cucurbita pepo). It damages the plants and causes the leaves to shrivel up. To date, only chemical fungicides
1360 - 1385/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.
are available. However, by-products from milk-processing factories have been proven to kill powdery mildew on zucchini. In many cases, milk is both faster and more effective. After two to three weeks of spraying with milk, the area of leaves infected is, in some cases, only a sixth or less of the area affected on plants treated with chemical fungicide. Crop Prot. (1999) 18, 489.
Flavonoid biosynthetic pathway Flavonoids are secondary metabolites derived from phenylalanine and acetate metabolism that play a variety of important roles in higher plants. Recent evidence from Arabidopsis supports the hypothesis that the flavonoid enzymes assemble as a macromolecular complex with contacts between multiple proteins. Evidence has also been found for post-translational modification (via a thioester bond) of chalcone isomerase. The importance of understanding the subcellular organization of elaborate enzyme systems is discussed in the context of metabolic engineering. Proc. Natl. Acad. Sci. U. S. A. (1999) 96, 12929–12934.
Wanted: misinterpreted science John Hodgson (j.hodgson@biotechnology. com) is interested in hearing about dubious statements from politicians, pressure groups and scientists that interpret the science poorly, or exaggerate the claims.
Policy briefs A collection of policy briefs on Biotechnology for Developing-Country Agriculture: Problems and Opportunities, (edited by Gabrielle J. Persley) is available from the International Food Policy Research Institute. The briefs include Biotechnology and Food and Nutrition Needs, Biotechnology and Animal Vaccines, The Role of the Private Sector, Disentangling Risks Safe Use of Biotechnology, Intellectual Property Protection, Research Policy and Management and Developing Appropriate Policies (www.cgiar.org/ifpri/2020/welcome.htm). January 2000, Vol. 5, No. 1
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Saving crop diversity The US Agricultural Research Service (ARS) maintains a network of 26 repositories nationwide that preserve and regenerate germplasm seed and other reproductive tissues of crops and their wild relatives. The system houses .400 000 accessions comprising .10 000 species. An accession is a genetically distinct group of plants, such as a crop variety or a wild subspecies. More than 200 organic seed farmers are growing 800 breeding lines of traditional crop plants provided by the National Plant Germplasm System. The Farmer Cooperative Genome Project, based in Junction City, OR, USA, was started in 1998 with a USDA Fund for Rural America grant. More details on the project appear on the web (http://www.ars.usda.gov/is/AR/archive/ oct99/seed1099.htm).
PTGS in plants Post-transcriptional gene silencing (PTGS) is a nucleotide sequence-specific defense mechanism that can target both cellular and viral mRNAs. A recent study analyzed three types of transgene-induced PTGS and one example of virus-induced PTGS in plants. In each case, antisense RNA complementary to the targeted mRNA was detected. These RNA molecules were of a uniform length, estimated at 25 nucleotides. Their accumulation required either transgene sense transcription or RNA virus replication. Thus, the 25-nucleotide antisense RNA is probably synthesized from an RNA template and might represent the specificity determinant of PTGS. Science (1999) 286, 950–952.
Compromised resistance in saponin-deficient plants Saponins are glycosylated plant secondary metabolites with potent antifungal properties that occur in many major food crops. The isolation of mutants defective in saponin biosynthesis represents a powerful strategy for evaluating the importance of these compounds in plant defense. A recent study has confirmed that saponin-deficient mutants of a diploid oat species, Avena strigosa, are indeed compromised in their resistance to a variety of fungal pathogens. Proc. Natl. Acad. Sci. U. S. A. (1999) 96, 12923–12928.
Health benefits of GM beet A genetically modified (GM) beet developed by Novartis uses genes from Jerusalem artichokes (Helianthus tuberosus) to convert almost all the sucrose in the beet root into fructans. These sweeteners cannot be digested but help to cultivate ‘friendly’ bacteria in the gut and fight cholesterol. ‘We need to show that gene technology can benefit consumers’ (Paul Tenning, Regulatory Affairs manager at Novartis Seeds AB, Sweden). The modified beet requires less spraying with chemical herbicides, so the environmental benefit should also be attractive to the consumers. However, US food and soft drinks exporters are concerned that they might have difficulty selling products in Europe that have been sweetened by GM sugar.
40% more GM crops in 1999 In 1999, the amount of land planted with genetically modified (GM) crops around the world is expected to have increased by .40%. Significant increases were in China, Argentina, Canada and South Africa. Three countries, Portugal, Romania and Ukraine, had commercial plantings for the first time in 1999.
USDA estimate of GM crops According to the US Agriculture Dept more than half of the US soybean crop this year was planted with genetically modified (GM) seeds, and corn and cotton were not far behind. The new USDA data, collected from interviews with farmers during the summer, were in line with seed companies’ estimates of how much land has been planted with bioengineered crops. Thirty percent of US corn and ~27% of US cotton planted in 1999 were of the Bt variety (which express Bacillus thuringiensis toxins), some 57% of US soybeans were planted with herbicide-resistant varieties, most of them Roundup Ready (Monsanto).
Milk as a fungicide The mould, Sphaerotheca fuliginea, appears as a powdery white growth on the leaves of cucumbers and zucchini (Cucurbita pepo). It damages the plants and causes the leaves to shrivel up. To date, only chemical fungicides
1360 - 1385/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.
are available. However, by-products from milk-processing factories have been proven to kill powdery mildew on zucchini. In many cases, milk is both faster and more effective. After two to three weeks of spraying with milk, the area of leaves infected is, in some cases, only a sixth or less of the area affected on plants treated with chemical fungicide. Crop Prot. (1999) 18, 489.
Flavonoid biosynthetic pathway Flavonoids are secondary metabolites derived from phenylalanine and acetate metabolism that play a variety of important roles in higher plants. Recent evidence from Arabidopsis supports the hypothesis that the flavonoid enzymes assemble as a macromolecular complex with contacts between multiple proteins. Evidence has also been found for post-translational modification (via a thioester bond) of chalcone isomerase. The importance of understanding the subcellular organization of elaborate enzyme systems is discussed in the context of metabolic engineering. Proc. Natl. Acad. Sci. U. S. A. (1999) 96, 12929–12934.
Wanted: misinterpreted science John Hodgson (j.hodgson@biotechnology. com) is interested in hearing about dubious statements from politicians, pressure groups and scientists that interpret the science poorly, or exaggerate the claims.
Policy briefs A collection of policy briefs on Biotechnology for Developing-Country Agriculture: Problems and Opportunities, (edited by Gabrielle J. Persley) is available from the International Food Policy Research Institute. The briefs include Biotechnology and Food and Nutrition Needs, Biotechnology and Animal Vaccines, The Role of the Private Sector, Disentangling Risks Safe Use of Biotechnology, Intellectual Property Protection, Research Policy and Management and Developing Appropriate Policies (www.cgiar.org/ifpri/2020/welcome.htm). January 2000, Vol. 5, No. 1
7