| BEN |
| BOTANICAL ELECTRONIC NEWS |
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| ISSN 1188-603X |
| No. 262 December 23, 2000 | aceska@freenet.victoria.tc.ca | Victoria, B.C. |
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The first BOTANY BC in the new decade, century and millennium will take place in Smithers, BC (54 deg. 45' N, 127 deg. 10' W). The activities will start on Thursday, July 26 (late afternoon) and end on Sunday, July 29, 2001. We will explore a wide variety of habitats from the valley bottom to alpine areas, from open dry scrub-steppe to wetlands and old moist forests. Illustrated talks will include: "Natural history of Bulkley Valley" (R. Pojar); "Wetlands of British Columbia" (W. Mackenzie); "Moonworts by daylight" (P. Williston); and "The all-embracing web: mycorrhizae, mushrooms, and you" (M. Kranabetter). Look for details and registration forms in an upcoming issue of BEN, and mark those days in your calendar!
Scientists announced in Nature that the first plant genome, that of Arabidopsis thaliana (aka Mouse-ear cress, Brassicaceae), has been entirely sequenced as part of a monumental five country project that has involved hundreds of scientists, marking the culmination of research that was initiated in 1994. This was completed under budget and ahead of schedule by four years. Completion of chromosomes 2 and 4 was reported at the end of last year, and with the release of sequences for chromosomes 1, 3 and 5, the Arabidopsis genome is completed. The announcement was made in the December 14 issue of Nature (released at 6 pm EST December 13 in North America).
The Arabidopsis genome contains 130 Megabases, encoding approximately 25,500 nuclear genes, 80 chloroplast genes and 60 mitochondrial genes. About 70 percent of the nuclear genes are duplicated within the code, so there are about 15,000 unique genes. The genome meets the same standard as the human genome of having no more than one mistake per 10,000 base pairs. The entire genomic sequence is completed, annotated, released and available in the public domain, on the Internet. As with the human genome, no one has any proprietary right on the sequence.
The significance of these data is that the Arabidopsis genome includes all of the information needed to construct an Arabidopsis plant. No matter that the plant is simple, inconspicuous and has never had economic impact outside of its role as a genetic model, it still is representative of all of the flowering plants, including crop plants. The major difference is that the size and quick generational time of Arabidopsis allows a lot of plants to be grown and the results of any cross to be available within less than two months. Further, the genome size is among the smallest of flowering plants. The small genome size also makes this plant among the easiest to transform, since there are fewer redundant genes than a lot of organisms have. The most important genes in crop plants are expected to have homologues in Arabidopsis and vice versa.
Of course to all botanists and plant biologists, the importance is obvious: oxygen-breathing animals owe their existence to photosynthetic organisms. We now know how plants are made in the barest (ACGT basepair) sense, but this is just the beginning of understanding plant complexity and variability. As with all science, what we do not know is more than what we do know (don't tell legislators, they don't want to know this). The next initiative in this, now, post-genomic period is NSF's so-called "2010 Project" to determine the function of all 25,500 Arabidopsis genes over the next decade. This project is also part of a worldwide effort and will be coordinated in a similar manner to the genome sequencing project, with results similarly publicly available.
Groups are currently working to establish Arabidopsis microarrays -- glass slides with representatives of thousands of genes that can be tested against mRNA of different tissue types to decipher the genes that are active at a given developmental stage or in a given tissue. Another group is establishing a collection of "gene knock-out" plants in which a single gene is genetically silenced in each of 25,500 plant lines so that there is a knock-out line for each plant gene. Each promoter and enhancer will also be identified and characterized. Another obvious part of this project is proteomics -- the categorization, identification and characterization of each polypeptide product produced by Arabidopsis. The current annual research output on Arabidopsis is nearly 2000 papers per year and is likely to accelerate. I presume that cryptographers are also investigating genome sequences for hidden information as well, as is underway for the human genome (a code is a code is a code?).
Although this could be compared to Gray's "Human Anatomy," as the genome will be the starting point for many future genetics projects, it could also be rightly compared to a Rosetta Stone, which will require a lot of translation to reach its full potential. Even once we understand of the genes, how they are controlled will be as important as what the genes do. Elements of how plants control their genes will be held in common with crop plants, other model animal systems (like nematodes and fruit flies) and humans as well.
In the future, are possibilities of using plants to produce crops that have not yet been dreamed of. These could include for instance higher yield crops for energy or amino acids essential to animals, crops with inborn disease and insect resistance that will reduce the need for pesticides and fungicides, plants that can (perhaps in combination with microbes) metabolize toxic compounds, and there are many other possibilities. Animal genes could be introduced into plants, for example, to cause bananas to produce vaccines for the third world, or to produce animal products (insulin?, human growth hormone?) in plant laticifers for mass harvest without sacrificing animals. Genetically-modified organisms will likely replace the chance experiments of plant breeders that used to produce hybrid seeds in the past through crosses of entire genomes, but can be more tightly focussed to specific plant characteristics.
Some news stories and original press releases are as follows:
For considerably more data on the project, see "Deciphering a Weed. Genomic Sequencing of Arabidopsis" by Nancy Federspiel in Plant Physiology (Plant Physiol, December 2000, Vol. 124, pp. 1456-1459), online at URL: http://www.plantphysiol.org/cgi/content/full/124/4/1456 Her account provides a strategic view and provides information about the molecular strategies used at each point in time.
The entire current issue of Plant Physiology is on Arabidopsis and is currently available for free at URL: http://www.plantphysiol.org/content/vol124/issue4/
Bubbia perrieri was described in 1963 based on a herbarium specimen collected in Madagascar in 1909. Later examination of the type specimen led to the description of a new genus Takhtajania and the transfer of Bubbia perrieri into this new genus in 1978. All we knew about Takhtajania perrieri was based on the 1909 herbarium collection. Since 1909 nobody saw one living plant of this species, until in 1994, the Malagasy plant collector Fanja Rasoavimbahoaka collected a flowering tree in the Anjahanaribe-Sud Special Reserve southwest of Andapa. The specimens were identified as Takhtajania in late May of 1997 by Missouri Botanical Garden botanist George E. Schatz. The new locality is 150 km from the original type locality.
Takhtajania perrieri is the only member of the family Winteraceae in the Afro-Madagascan flora. The rediscovery of living plants of Takhtajania started a multidisciplinary study of this genus and its relatives from the family Winteraceae. The results of these studies were published in a special issue of the Annals of Missouri Botanical Garden 87(3) with eleven articles on various aspects of Takhtajania and the Winteraceae family.
This single issue of the Annals of the Missouri Botanical Garden 87(3) is available from the MO Botanical Garden Press is US$35.00 (plus US$6.00 to customers in Canada). All orders must be prepaid, please contact Brian Gardner with a credit card number or send a check.
I would like to thank all of you who submitted notes and articles to BEN in 2000. My thanks also go to all BEN readers for their patience, to all BEN subscribers for remaining faithful to BEN, and to all those, who know how and when to use the delete button (although they may be gone by now). I have to thank to my ghost writers whose English is better than mine. The Victoria Freenet Association has provided the Internet services that keep BEN alive, and Dr. Scott Russell has faithfully served as the Chief Web Master. Poor man, he has to read every BEN issue from the beginning to the end. Many thanks to all of you and all the best in the coming year.
- Adolf Ceska