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Chinese GM rice
trends in plant science Headlines
Priority for conservation hotspots For twice the cost of a Pathfinder mission to Mars, which has been justified largely on biodiversity grounds (in the search for extraterrestrial life), many of the endangered plant and animal species on Earth could be saved from extinction. By investing $500 million a year over the next five years in conservation hot spots many species at risk could be saved. Hot spots range from the Andes to southwest Australia and from Kenya to Caucasus and contain the habitats of 133 149 plant species (44% of the worldwide total) and 9645 vertebrate species (~35% of the total). They contain exceptional concentrations of native species but are experiencing rapid losses of their natural habitat. Not since the demise of the dinosaurs have so many species been under threat. Declining species numbers will have an impact on food, medicines and materials and will hamper the work of scientists in answering some of the great questions of biology. Nature (2000) 403, 853–858.
Genetic modification is not unnatural Norman Borlaug, 84, Nobel Prize winner for his achievements in breeding high-yielding wheat said, ‘Genetically modified organisms are the result of a natural process that was going on long before humans became involved’. Species barriers are significant in nature, but not inviolate. Primitive farmers selected a wild grass (which came to be known as wheat) that had seven chromosomes and crossed it with another plant to create a new species with 14 chromosomes – descendants are used today for pasta and unleavened bread. Another species later emerged with 21 chromosomes, which is known today as ‘bread wheat’. Almost all crops under cultivation today are the result of shuffled genes. Conventional crosses include many genes that give the plants unwanted traits that need to be outcrossed. Now, plant breeders can isolate precisely the genes they want and insert them directly into plants. Borlaug suggested that the appropriate response to objecting to the use of unrelated genes is not to reject the crops but to make sure that they are thoroughly tested under government regulation.
Veggie with rat gene A rat gene has been introduced in broccolini™ to enhance vitamin C levels. Broccolini is a cross between broccoli and a Chinese kale, and took eight years to develop. The new plants contain up to seven times the quantity of vitamin C, and it is thought that similar experiments would probably be successful with other plants such as rice and tomatoes. Broccolini retains color and stays fresh longer and could eventually help overcome vitamin deficiencies. Mol. Breed. (2000) 6, 73–78.
Ancestor of green plants Mesostigma viride, a unicellular freshwater alga that appeared ~800 million years ago, is a living descendant of the ancestor of all green algae and land plants, and belongs to the earliest diverging green plant lineage discovered to date. Phylogenetic analyses of chloroplast genome sequences show that Mesostigma emerged before the divergence of the Streptophyta (land plants and their closest green algal relatives the charophytes) and the Chlorophyta (the rest of green algae). Nature (2000) 403, 649–652.
Chinese GM rice Chinese scientists have developed a genetically altered strain of rice that is resistant to herbicides, and have claimed it to be China’s first transgenetic rice variety. China reportedly has 300 000 ha of GM crops under cultivation; cotton being the most common. However, some Chinese lawmakers are calling for improved control of GM foods.
Vitamin supplements through GM plants Vitamins A and E are linked by common biosynthetic pathways and functions. Plants make carotenoids and tocopherols (vitamin E) in plastids, including chloroplasts, where they function as pigments and antioxidants in photosynthesis. Extra carotenoids and tocopherols reportedly enhance cardiovascular health, prevent cancer and slow aging processes in humans. An Agrobacteriummediated transformation has been used to introduce the entire b-carotene biosynthetic pathway into the rice endosperm in a single transformation event using genes for a daffodil (Narcissus pseudonarcissus) phytoene synthase, a bacterial desaturase and a daffodil cyclase, to produce golden yellow rice. Just 300 g of rice each day should prevent vitamin A deficiency, and rice breeders in Asia, Africa and Latin America are now busy transferring the trait to common varieties. Science (2000) 287, 303–305.
Cross pollination in corn John Jemison (University of Maine’s Cooperative Extension Farm, USA) found that the highest incidence of cross pollination between Roundup Ready ® corn and nongenetically modified corn was 1% in the first six rows of a field planted 30.5 m downwind. At a distance of 305 m (which is usually allowed to separate GM corn and non-GM corn), cross-pollination could not be shown. Jemison is repeating the study this spring.
Triple-resistant canola weeds Scientists have long said the use of herbicide-tolerant canola (oilseed rape; Brassica napus) would eventually result in multi-resistant plants, and indeed volunteer canola that is resistant to Roundup™, Liberty™ and Pursuit™ chemicals has been found in a field in northern Alberta, Canada. The plants are probably the result of planting a field of Monsanto’s canola Quest™, Aventis’ canola Innovator™ and Cyanamid’s Smart™ canola (not GM) in closely adjacent fields. Double resistance was observed the first year and triple resistance the following year. Researchers now recommend a distance of at least 200 m between genetically modified canola varieties and any other canola field to prevent gene crossing. The first official case of natural gene stacking in canola is not seen as a great problem other than a major production headache for Canadian farmers. Although the volunteers can still be killed by a range of other herbicides, this discovery of triple resistance is potentially a road towards accelerating the ‘arms race’ in weed control, eventually reducing herbicide options. Therefore, valued traits should not be used unless and until genetic isolation can be employed, such as plastid transformation or rehabilitation of the ‘terminator technology’.
1360 - 1385/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.
May 2000, Vol. 5, No. 5
189
Priority for conservation hotspots For twice the cost of a Pathfinder mission to Mars, which has been justified largely on biodiversity grounds (in the search for extraterrestrial life), many of the endangered plant and animal species on Earth could be saved from extinction. By investing $500 million a year over the next five years in conservation hot spots many species at risk could be saved. Hot spots range from the Andes to southwest Australia and from Kenya to Caucasus and contain the habitats of 133 149 plant species (44% of the worldwide total) and 9645 vertebrate species (~35% of the total). They contain exceptional concentrations of native species but are experiencing rapid losses of their natural habitat. Not since the demise of the dinosaurs have so many species been under threat. Declining species numbers will have an impact on food, medicines and materials and will hamper the work of scientists in answering some of the great questions of biology. Nature (2000) 403, 853–858.
Genetic modification is not unnatural Norman Borlaug, 84, Nobel Prize winner for his achievements in breeding high-yielding wheat said, ‘Genetically modified organisms are the result of a natural process that was going on long before humans became involved’. Species barriers are significant in nature, but not inviolate. Primitive farmers selected a wild grass (which came to be known as wheat) that had seven chromosomes and crossed it with another plant to create a new species with 14 chromosomes – descendants are used today for pasta and unleavened bread. Another species later emerged with 21 chromosomes, which is known today as ‘bread wheat’. Almost all crops under cultivation today are the result of shuffled genes. Conventional crosses include many genes that give the plants unwanted traits that need to be outcrossed. Now, plant breeders can isolate precisely the genes they want and insert them directly into plants. Borlaug suggested that the appropriate response to objecting to the use of unrelated genes is not to reject the crops but to make sure that they are thoroughly tested under government regulation.
Veggie with rat gene A rat gene has been introduced in broccolini™ to enhance vitamin C levels. Broccolini is a cross between broccoli and a Chinese kale, and took eight years to develop. The new plants contain up to seven times the quantity of vitamin C, and it is thought that similar experiments would probably be successful with other plants such as rice and tomatoes. Broccolini retains color and stays fresh longer and could eventually help overcome vitamin deficiencies. Mol. Breed. (2000) 6, 73–78.
Ancestor of green plants Mesostigma viride, a unicellular freshwater alga that appeared ~800 million years ago, is a living descendant of the ancestor of all green algae and land plants, and belongs to the earliest diverging green plant lineage discovered to date. Phylogenetic analyses of chloroplast genome sequences show that Mesostigma emerged before the divergence of the Streptophyta (land plants and their closest green algal relatives the charophytes) and the Chlorophyta (the rest of green algae). Nature (2000) 403, 649–652.
Chinese GM rice Chinese scientists have developed a genetically altered strain of rice that is resistant to herbicides, and have claimed it to be China’s first transgenetic rice variety. China reportedly has 300 000 ha of GM crops under cultivation; cotton being the most common. However, some Chinese lawmakers are calling for improved control of GM foods.
Vitamin supplements through GM plants Vitamins A and E are linked by common biosynthetic pathways and functions. Plants make carotenoids and tocopherols (vitamin E) in plastids, including chloroplasts, where they function as pigments and antioxidants in photosynthesis. Extra carotenoids and tocopherols reportedly enhance cardiovascular health, prevent cancer and slow aging processes in humans. An Agrobacteriummediated transformation has been used to introduce the entire b-carotene biosynthetic pathway into the rice endosperm in a single transformation event using genes for a daffodil (Narcissus pseudonarcissus) phytoene synthase, a bacterial desaturase and a daffodil cyclase, to produce golden yellow rice. Just 300 g of rice each day should prevent vitamin A deficiency, and rice breeders in Asia, Africa and Latin America are now busy transferring the trait to common varieties. Science (2000) 287, 303–305.
Cross pollination in corn John Jemison (University of Maine’s Cooperative Extension Farm, USA) found that the highest incidence of cross pollination between Roundup Ready ® corn and nongenetically modified corn was 1% in the first six rows of a field planted 30.5 m downwind. At a distance of 305 m (which is usually allowed to separate GM corn and non-GM corn), cross-pollination could not be shown. Jemison is repeating the study this spring.
Triple-resistant canola weeds Scientists have long said the use of herbicide-tolerant canola (oilseed rape; Brassica napus) would eventually result in multi-resistant plants, and indeed volunteer canola that is resistant to Roundup™, Liberty™ and Pursuit™ chemicals has been found in a field in northern Alberta, Canada. The plants are probably the result of planting a field of Monsanto’s canola Quest™, Aventis’ canola Innovator™ and Cyanamid’s Smart™ canola (not GM) in closely adjacent fields. Double resistance was observed the first year and triple resistance the following year. Researchers now recommend a distance of at least 200 m between genetically modified canola varieties and any other canola field to prevent gene crossing. The first official case of natural gene stacking in canola is not seen as a great problem other than a major production headache for Canadian farmers. Although the volunteers can still be killed by a range of other herbicides, this discovery of triple resistance is potentially a road towards accelerating the ‘arms race’ in weed control, eventually reducing herbicide options. Therefore, valued traits should not be used unless and until genetic isolation can be employed, such as plastid transformation or rehabilitation of the ‘terminator technology’.
1360 - 1385/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved.
May 2000, Vol. 5, No. 5
189