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Agro-a-go-go
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News & Comment
TRENDS in Plant Science Vol.6 No.11 November 2001
In Brief
Transplastomic: the new transgenic An international group of scientists has developed a method to introduce transgenes into the chloroplast genomes of tomato (Lycopersicon esculentum) [Nat. Biotechnol. (2001) 19, 870–875]. The transgene system depends on a chloroplast target sequence that undergoes homologous recombination, thereby introducing the transgene into the chloroplast genome. The group generated ‘transplastomic’ plants that harbored the aadA gene, which confers antibiotic resistance. The researchers found the aadA protein accumulated in leaves and also in young and ripened fruits. Because the target sequence is highly conserved in dicot plants, the vector system could be useful in a variety of untested plant species. The transplastomic system should be useful for overcoming gene silencing, a problem with current transgenics. TS
Two achenes are better than one
Catnip gets buggy
Catnip (Nepeta cataria) not only excites cats, it also repels mosquitoes. Joel Coats and Chris Peterson at Iowa State University (Ames, IA, USA) found that oils from catnip are ten times more effective at repelling mosquitoes than DEET is, a chemical used in current repellents. The results were reported at the American Chemical Society’s meeting in Chicago. Catnip contains two forms of nepetalacetone that when smeared on one-half of a glass tube repel ~80% of the insects away from the volatile substances. Catnip is also effective in repelling cockroaches. When asked whether the compounds would attract cats, Coats told reporters, ‘If you sat near a cat, you might generate more interest than usual. They might want to play.’ [Collins, V. (2001) The Herald (Glasgow), 28 August, p. 3] TS
Sometimes the simplest questions reveal the most surprising insights. For example, the composite Leontodon longirrostris produces two kinds of achenes (seeds): why? Emilio Ruiz de Clavijo (University of Cordoba, Spain) has examined that question and discovered that the strategy helps to ensure both the in situ persistence and spread of this annual weed [Weed Res. 41 (2001) 275–286]. The fewer, heavier, achenes with no pappus, which are peripherally situated on the seed head, fall near the plant and contribute to the soil-borne seed bank; the more numerous, centrally located, lighter, pappate achenes blow away on the wind and colonize new areas. NC
Damage control Many people fear that flora in the Antarctic will suffer damage from ultra-violet (UV) light because of the loss of the protective ozone over the South Pole, which would normally filter out UV. A team of scientists now reports that Antarctic plants might be more resilient to UV damage than was http://plants.trends.com
thought originally. Led by Daniela Lud from The Netherlands Institute of Ecology (Yerseke, The Netherlands), the group has found that mosses, liverworts and other Antarctic species produce large amounts of pigments and carotenoids in response to high levels of UV exposure. The pigments act as sunscreens by blocking UV light and reducing oxygen radicals from UV damage. (Agence France Presse, 5 September 2001) TS
Internet-counselling for stressed plants? In our own frantic lives, it is easy to forget that other organisms suffer stress too. Indeed, plants are subjected to so many environmental stresses that a website (http://www.plantstress.com/) is devoted
to the topic. And given the impact that abiotic insults – such as stresses caused by drought, cold, heat, salinity and mineral deficiency – can have on plant health and agricultural production, these are major problems on a global scale. Successfully tackling these issues will involve the pooling of research and expertise from many different disciplines. Thus, an important aim of the website is to facilitate the exchange of information in this area. NC
GM elm Over a 30-year span, Dutch elm disease in the UK destroyed more than 25 million of the 30 million English elm trees (Ulmus procera), thus altering the UK countryside. To overcome this disease, a group of scientists has created the first genetically modified elm trees to combat the disease, to bring the English elm back to the countryside. Kevan Gartland, who heads the research at the University of Abertay (Dundee, UK) has been working on transgenic elms for a decade. Details of the transgenic modification have not been disclosed but the GM elms contain a gene that confers resistance to the fungus that causes Dutch elm disease. Tests are now under way to test levels of fungal resistance in the transgenics. Gartland told reporters, ‘Any potential release of the GM trees to the environment will be subject to rigorous risk assessment.’ [Meek, J. (2001) The Guardian (London), 28 August, p. 3] TS
Agro-a-go-go Agrobacterium tumefaciens is a bacterium that normally produces crown gall in infected plants but has currently found use as a delivery system of transgenes. Researchers now report how the infection changes a plant’s gene expression [Proc. Natl. Acad. Sci. U. S. A. (2001) 98, 10954–10959]. The group, headed by Luca Comai, infected Ageratum conyzoides cells with Agrobacterium, and detected which genes had altered levels of transcript. Agrobacterium normally changes plant hormone levels, but the group used a strain that lacked that capability. Four of the affected genes are regulated in a similar fashion in nonpathogenic bacteria. Surprisingly, Agrobacterium affected a
1360-1385/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
News & Comment
TRENDS in Plant Science Vol.6 No.11 November 2001
In Brief
Transplastomic: the new transgenic An international group of scientists has developed a method to introduce transgenes into the chloroplast genomes of tomato (Lycopersicon esculentum) [Nat. Biotechnol. (2001) 19, 870–875]. The transgene system depends on a chloroplast target sequence that undergoes homologous recombination, thereby introducing the transgene into the chloroplast genome. The group generated ‘transplastomic’ plants that harbored the aadA gene, which confers antibiotic resistance. The researchers found the aadA protein accumulated in leaves and also in young and ripened fruits. Because the target sequence is highly conserved in dicot plants, the vector system could be useful in a variety of untested plant species. The transplastomic system should be useful for overcoming gene silencing, a problem with current transgenics. TS
Two achenes are better than one
Catnip gets buggy
Catnip (Nepeta cataria) not only excites cats, it also repels mosquitoes. Joel Coats and Chris Peterson at Iowa State University (Ames, IA, USA) found that oils from catnip are ten times more effective at repelling mosquitoes than DEET is, a chemical used in current repellents. The results were reported at the American Chemical Society’s meeting in Chicago. Catnip contains two forms of nepetalacetone that when smeared on one-half of a glass tube repel ~80% of the insects away from the volatile substances. Catnip is also effective in repelling cockroaches. When asked whether the compounds would attract cats, Coats told reporters, ‘If you sat near a cat, you might generate more interest than usual. They might want to play.’ [Collins, V. (2001) The Herald (Glasgow), 28 August, p. 3] TS
Sometimes the simplest questions reveal the most surprising insights. For example, the composite Leontodon longirrostris produces two kinds of achenes (seeds): why? Emilio Ruiz de Clavijo (University of Cordoba, Spain) has examined that question and discovered that the strategy helps to ensure both the in situ persistence and spread of this annual weed [Weed Res. 41 (2001) 275–286]. The fewer, heavier, achenes with no pappus, which are peripherally situated on the seed head, fall near the plant and contribute to the soil-borne seed bank; the more numerous, centrally located, lighter, pappate achenes blow away on the wind and colonize new areas. NC
Damage control Many people fear that flora in the Antarctic will suffer damage from ultra-violet (UV) light because of the loss of the protective ozone over the South Pole, which would normally filter out UV. A team of scientists now reports that Antarctic plants might be more resilient to UV damage than was http://plants.trends.com
thought originally. Led by Daniela Lud from The Netherlands Institute of Ecology (Yerseke, The Netherlands), the group has found that mosses, liverworts and other Antarctic species produce large amounts of pigments and carotenoids in response to high levels of UV exposure. The pigments act as sunscreens by blocking UV light and reducing oxygen radicals from UV damage. (Agence France Presse, 5 September 2001) TS
Internet-counselling for stressed plants? In our own frantic lives, it is easy to forget that other organisms suffer stress too. Indeed, plants are subjected to so many environmental stresses that a website (http://www.plantstress.com/) is devoted
to the topic. And given the impact that abiotic insults – such as stresses caused by drought, cold, heat, salinity and mineral deficiency – can have on plant health and agricultural production, these are major problems on a global scale. Successfully tackling these issues will involve the pooling of research and expertise from many different disciplines. Thus, an important aim of the website is to facilitate the exchange of information in this area. NC
GM elm Over a 30-year span, Dutch elm disease in the UK destroyed more than 25 million of the 30 million English elm trees (Ulmus procera), thus altering the UK countryside. To overcome this disease, a group of scientists has created the first genetically modified elm trees to combat the disease, to bring the English elm back to the countryside. Kevan Gartland, who heads the research at the University of Abertay (Dundee, UK) has been working on transgenic elms for a decade. Details of the transgenic modification have not been disclosed but the GM elms contain a gene that confers resistance to the fungus that causes Dutch elm disease. Tests are now under way to test levels of fungal resistance in the transgenics. Gartland told reporters, ‘Any potential release of the GM trees to the environment will be subject to rigorous risk assessment.’ [Meek, J. (2001) The Guardian (London), 28 August, p. 3] TS
Agro-a-go-go Agrobacterium tumefaciens is a bacterium that normally produces crown gall in infected plants but has currently found use as a delivery system of transgenes. Researchers now report how the infection changes a plant’s gene expression [Proc. Natl. Acad. Sci. U. S. A. (2001) 98, 10954–10959]. The group, headed by Luca Comai, infected Ageratum conyzoides cells with Agrobacterium, and detected which genes had altered levels of transcript. Agrobacterium normally changes plant hormone levels, but the group used a strain that lacked that capability. Four of the affected genes are regulated in a similar fashion in nonpathogenic bacteria. Surprisingly, Agrobacterium affected a
1360-1385/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.