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Pesticide field filter
trends in plant science Headlines
Crossing rice with its wild cousins works wonders Unlikely crosses between wild species of rice and their commercial relatives are boosting rice yields by a staggering 10–20%. Researchers say that this approach has also produced other unexpected benefits, including protection against a virus. In the early 1990s, Susan McCouch (Cornell University, NY, USA) started crossing wild species with commercial varieties of rice derived from two Oryza sativa subspecies, indica and japonica, a rice species favored in Southeast Asia. Researchers are combing through the DNA of the hybrid plants to identify the genes that gave the improved traits. Using the library of genes available in the wild relatives of crop plants could make crop genetic engineering unnecessary. www.newscientist.com/ns/19991127/newsstory8.html
Licensing problems slow adoption of GM crops in India The Indian government took a conscious decision to promote transgenic plant research at the beginning of 1999, but is in no hurry to make a policy on the commercial introduction of GM foods. Their policy is to continue with research on transgenic crops while simultaneously strengthening their laboratory system to be able to evaluate the safety of GM foods whenever they are ready to be introduced. In the past ten years, India has spent US$15 million on transgenic plant research. Pending an agreement on benefit sharing, India has refused to give Monsanto clearance to introduce its proprietary genes for crops such as rice and sugar cane. In July 1999, the Monsanto Research Centre in Bangalore sought permission to import 33 plasmid DNA constructs from the inventory of its parent company in the USA. The request was turned down on the grounds that it would not be cleared until Monsanto signed an agreement with the government spelling out exactly how commercial benefits would be shared.
Pesticide field filter Regulatory agencies around the world are calling for farmers to use so-called ‘buffer zones’ of unplanted ground or non-crop vegetation around crops to catch droplets of pesticide spray carried by the wind. Currently only The Netherlands has mandated that its farmers use windbreaks. The British and Australian governments are starting to promote the idea. Franklin R. Hall and colleagues (Ohio State University and USDA-NRCS, USA) have performed wind-tunnel experiments and found that trees with needles offer a larger surface area for collecting sprays than broadleaved trees, and also create swirling air patterns that lead to more droplets being deposited. http://www.quad-net.com/archive/ GREEN11-19OSU
Ag-biotechnology for developing countries Iron deficiency, lack of vitamin A and protein malnutrition are common problems in many parts of the world, causing widespread illness. Rice naturally contains only small amounts of iron and no vitamin A. Ingo Potrykus (Swiss Federal Institute of Technology, Zurich, Switzerland) told Nature Biotechnology’s Agbiotech conference in London (UK) how he and his colleagues are engineering rice to provide vitamin A, as well as much more iron. Another team, headed by C.S. Prakash (Tuskeegee University, AB, USA) is trying to pack more and better proteins into sweet potatoes (Ipomoea batatus). Sweet potato is a staple food in sub-Saharan Africa and the south Pacific, where many people are malnourished because sweet potato has low levels of protein and few essential amino acids. If further development and safety trials are satisfactory, both the new rice variety and the protein-rich sweet potato could one day improve the health of people in developing nations around the world.
Modified soya beans are cracking up in the heat Bill Vencill (University of Georgia, Athens, USA) has found that hot climates do not agree with Monsanto’s herbicide-resistant soya beans, causing crop losses of up to 40%. Stems of virtually all the Monsanto beans split open as the first leaves began to emerge, compared with between 50 and 70% of the other test plants. This same phenomenon had occurred on farms, but had been blamed on fungal disease. Vencill suspects that the phenomenon is the result of changes in plant physiology caused by the addition of the genes that make the beans resistant to glyphosate. Plants carrying these genetic alterations have been shown to produce up to 20% more lignin, which might make the plants more brittle. Plants resistant to a different herbicide, gluphosinate, were not affected by the heat.
Bs2 pepper gene confers resistance The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The Bs2 locus has been isolated and the gene identified by co-expression with avrBs2 in an Agrobacterium-mediated transient assay. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species. Proc. Natl. Acad. Sci. U. S. A. 96, 14153–14158
Hypersensitive reaction to pathogen infection
Farmers reduce insecticide use
Reactive oxygen intermediates (ROI) play a critical role in defending plants against invading pathogens. They are thought to activate programmed cell death (PCD) to induce antimicrobial defenses. Expression of ROIdetoxifying enzymes, such as ascorbate peroxidase (APX) and catalase (CAT), are suppressed. Transgenic plants with a reduced capability to detoxify ROI (i.e. antisense APX or CAT) are found to be hypersensitive to pathogen attack. It is thought that the suppression of ROI-scavenging enzymes during the hypersensitive response plays an important role in enhancing pathogen-induced PCD. Proc. Natl. Acad. Sci. U. S. A. 96, 14165–14170
In the USA, a recent Iowa State University study shows that farmers in the Midwest who planted Bt corn between 1996 and 1998 reduced their insecticide use each year. Researchers found that 13% of the farmers who planted Bt corn in 1996 decreased their insecticide use, 19% in 1997 and 26% in 1998. About half of the Bt-corn farmers surveyed said that they do not use insecticides. http://www.yankton.net/stories/112299/ new_1122990012.html
1360 - 1385/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.
Internet news media, edited by Gert E. de Vries.
February 2000, Vol. 5, No. 2
55
Crossing rice with its wild cousins works wonders Unlikely crosses between wild species of rice and their commercial relatives are boosting rice yields by a staggering 10–20%. Researchers say that this approach has also produced other unexpected benefits, including protection against a virus. In the early 1990s, Susan McCouch (Cornell University, NY, USA) started crossing wild species with commercial varieties of rice derived from two Oryza sativa subspecies, indica and japonica, a rice species favored in Southeast Asia. Researchers are combing through the DNA of the hybrid plants to identify the genes that gave the improved traits. Using the library of genes available in the wild relatives of crop plants could make crop genetic engineering unnecessary. www.newscientist.com/ns/19991127/newsstory8.html
Licensing problems slow adoption of GM crops in India The Indian government took a conscious decision to promote transgenic plant research at the beginning of 1999, but is in no hurry to make a policy on the commercial introduction of GM foods. Their policy is to continue with research on transgenic crops while simultaneously strengthening their laboratory system to be able to evaluate the safety of GM foods whenever they are ready to be introduced. In the past ten years, India has spent US$15 million on transgenic plant research. Pending an agreement on benefit sharing, India has refused to give Monsanto clearance to introduce its proprietary genes for crops such as rice and sugar cane. In July 1999, the Monsanto Research Centre in Bangalore sought permission to import 33 plasmid DNA constructs from the inventory of its parent company in the USA. The request was turned down on the grounds that it would not be cleared until Monsanto signed an agreement with the government spelling out exactly how commercial benefits would be shared.
Pesticide field filter Regulatory agencies around the world are calling for farmers to use so-called ‘buffer zones’ of unplanted ground or non-crop vegetation around crops to catch droplets of pesticide spray carried by the wind. Currently only The Netherlands has mandated that its farmers use windbreaks. The British and Australian governments are starting to promote the idea. Franklin R. Hall and colleagues (Ohio State University and USDA-NRCS, USA) have performed wind-tunnel experiments and found that trees with needles offer a larger surface area for collecting sprays than broadleaved trees, and also create swirling air patterns that lead to more droplets being deposited. http://www.quad-net.com/archive/ GREEN11-19OSU
Ag-biotechnology for developing countries Iron deficiency, lack of vitamin A and protein malnutrition are common problems in many parts of the world, causing widespread illness. Rice naturally contains only small amounts of iron and no vitamin A. Ingo Potrykus (Swiss Federal Institute of Technology, Zurich, Switzerland) told Nature Biotechnology’s Agbiotech conference in London (UK) how he and his colleagues are engineering rice to provide vitamin A, as well as much more iron. Another team, headed by C.S. Prakash (Tuskeegee University, AB, USA) is trying to pack more and better proteins into sweet potatoes (Ipomoea batatus). Sweet potato is a staple food in sub-Saharan Africa and the south Pacific, where many people are malnourished because sweet potato has low levels of protein and few essential amino acids. If further development and safety trials are satisfactory, both the new rice variety and the protein-rich sweet potato could one day improve the health of people in developing nations around the world.
Modified soya beans are cracking up in the heat Bill Vencill (University of Georgia, Athens, USA) has found that hot climates do not agree with Monsanto’s herbicide-resistant soya beans, causing crop losses of up to 40%. Stems of virtually all the Monsanto beans split open as the first leaves began to emerge, compared with between 50 and 70% of the other test plants. This same phenomenon had occurred on farms, but had been blamed on fungal disease. Vencill suspects that the phenomenon is the result of changes in plant physiology caused by the addition of the genes that make the beans resistant to glyphosate. Plants carrying these genetic alterations have been shown to produce up to 20% more lignin, which might make the plants more brittle. Plants resistant to a different herbicide, gluphosinate, were not affected by the heat.
Bs2 pepper gene confers resistance The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The Bs2 locus has been isolated and the gene identified by co-expression with avrBs2 in an Agrobacterium-mediated transient assay. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species. Proc. Natl. Acad. Sci. U. S. A. 96, 14153–14158
Hypersensitive reaction to pathogen infection
Farmers reduce insecticide use
Reactive oxygen intermediates (ROI) play a critical role in defending plants against invading pathogens. They are thought to activate programmed cell death (PCD) to induce antimicrobial defenses. Expression of ROIdetoxifying enzymes, such as ascorbate peroxidase (APX) and catalase (CAT), are suppressed. Transgenic plants with a reduced capability to detoxify ROI (i.e. antisense APX or CAT) are found to be hypersensitive to pathogen attack. It is thought that the suppression of ROI-scavenging enzymes during the hypersensitive response plays an important role in enhancing pathogen-induced PCD. Proc. Natl. Acad. Sci. U. S. A. 96, 14165–14170
In the USA, a recent Iowa State University study shows that farmers in the Midwest who planted Bt corn between 1996 and 1998 reduced their insecticide use each year. Researchers found that 13% of the farmers who planted Bt corn in 1996 decreased their insecticide use, 19% in 1997 and 26% in 1998. About half of the Bt-corn farmers surveyed said that they do not use insecticides. http://www.yankton.net/stories/112299/ new_1122990012.html
1360 - 1385/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.
Internet news media, edited by Gert E. de Vries.
February 2000, Vol. 5, No. 2
55