Progress 11/15/01 to 11/14/04
Outputs
Crown gall disease causes millions of dollars of damage in fruit and nut orchards, vineyards, and nurseries worldwide. Tumors on roots result from excessive production of the phytohormone auxin in plant cells genetically transformed by Agrobacterium tumefaciens. High auxin levels result from expression of two oncogenes transferred stably into the plant genome from A. tumefaciens: iaaM and iaaH. We have generated transgenic apple rootstocks resistant to crown gall. Inactivation of iaaM abolished gall formation on apple tree roots. Transgenes designed to express double-stranded RNA from a portion of iaaM inactivated the wild-type iaaM oncogene and prevented crown gall disease on roots of transgenic apple trees. Silencing A. tumefaciens T-DNA oncogenes is a new and effective method to produce plants resistant to crown gall disease. This technology has the potential to prevent crown gall disease in any crop plant amenable to introduction of transgenes.
Impacts
Issue: Who cares and why? Crown gall disease causes millions of dollars of damage in fruit and nut orchards, vineyards, and nurseries worldwide. Losses in Oregon are ~$400,000 in a typical year. Currently there is no effective means to prevent crown gall (except for our method). What has been done? We used gene-silencing technology to generate transgenic apple rootstocks resistant to crown gall. Impact This technology has the potential to prevent crown gall disease in any crop plant amenable to introduction of transgenes. Once gall-resistant transgenic rootstocks are produced, no additional input is required.
Publications
- Hodges, L.D., Cuperus, J. and W. Ream. Agrobacterium rhizogenes GALLS Protein Substitutes for A. tumefaciens Single-Stranded DNA-Binding Protein VirE2. J. Bacteriol. 186: 3065-3077 (2004).
- Viss, W., Pitrak, J., Humann, J.L., Cook, M., Driver, J. and W. Ream. Crown-gall-resistant transgenic apple trees that silence Agrobacterium tumefaciens oncogenes. Molecular Breeding 12: 283-295 (2003).
- Lee, H., Humann, J., Pitrak, J., Cuperus, J., Parks, T.D., Whistler, C., Mok. M. and W. Ream. Translational Start Sequences Affect the Efficiency of Silencing of Agrobacterium tumefaciens T-DNA Oncogenes. Plant Physiol. 133: 966-977 (2003).
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Progress 01/01/03 to 12/31/03
Outputs
Crown gall disease is an economically significant problem in fruit and nut orchards, vineyards, and nurseries worldwide. Tumors on stems and leaves result from excessive production of the phytohormones auxin and cytokinin in plant cells genetically transformed by Agrobacterium tumefaciens. High phytohormone levels result from expression of three oncogenes transferred stably into the plant genome from A. tumefaciens: iaaM, iaaH, and ipt. The iaaM and iaaH oncogenes direct auxin biosynthesis, and the ipt oncogene causes cytokinin production. In contrast to other tissues, roots do not respond to high cytokinin levels, and auxin overproduction is sufficient to cause tumor growth on roots. Inactivation of iaaM abolished gall formation on apple tree roots. Transgenes designed to express double-stranded RNA from iaaM and ipt sequences prevented crown gall disease on roots of transgenic apple trees. Sequences required for oncogene silencing included a translation start site.
A transgene encoding a translatable sense-strand RNA from the 5' end of iaaM silenced the iaaM oncogene, but deletion of the translation start site abolished the ability of the transgene to silence iaaM. Silencing A. tumefaciens T-DNA oncogenes is a new and effective method to produce plants resistant to crown gall disease.
Impacts
Crown gall disease causes millions of dollars of damage in fruit and nut orchards, vineyards, and nurseries worldwide. We have generated transgenic apple rootstocks resistant to crown gall. This technology has the potential to prevent crown gall disease in any crop plant amenable to introduction of transgenes.
Publications
- Lee, H., Humann, J., Pitrak, J., Cuperus, J., Parks, T.D., Whistler, C., Mok. M. and W. Ream. (2003) Translational Start Sequences Affect the Efficiency of Silencing of Agrobacterium tumefaciens T-DNA Oncogenes. Plant Physiol. 133:966-977.
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Progress 11/15/01 to 11/15/02
Outputs
Crown gall disease is a significant problem in fruit and nut orchards, vineyards, and nurseries. Tumors on roots result from excessive production of the phytohormones auxin and cytokinin in plant cells genetically transformed by Agrobacterium tumefaciens. High phytohormone levels result from expression of three oncogenes transferred stably into the plant genome from A. tumefaciens: iaaM, iaaH, and ipt. Inactivation of iaaM abolished gall formation on apple tree roots. A transgene designed to express double-stranded RNA from a portion of the iaaM oncogene prevented crown gall disease on roots of transgenic apple trees. The goal of our research was to provide a new, more effective method to produce fruit and nut trees, grapevines, and other crop plants resistant to crown gall disease. Using a gene silencing strategy we produced six transgenic apple lines that were completely resistant to crown gall.
Impacts
Crown gall disease is a significant problem in fruit and nut orchards, vineyards, and nurseries. Using a gene silencing strategy we produced six transgenic apple lines that were completely resistant to crown gall. Our oncogene silencing technology can be used to prevent crown gall disease in any crop.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Agrobacterium tumefaciens causes crown gall disease on a wide variety of crops, including fruit and nut trees, grapevines, cane berries, roses, and other nursery crops. Crown gall tumors result from transfer to and expression of three A. tumefaciens oncogenes in plant cells. This leads to overproduction of plant growth hormones auxin and cytokinin, which causes unorganized plant cell growth. We constructed transgenes designed to trigger post-transcriptional gene silencing of these oncogenes. These transgenes blocked production of excess auxin that normally occurs as a result of A. tumefaciens infection. This interferred with crown gall tumor development. These transgenes have been introduced into apple where they protected the roots from crown gall. Patent Application No. US99/26100 entitled "Plants Having Enhanced Gall Resistance" was filed on November 4, 1999, and is still pending.
Impacts
We have proven that our strategy to produce plants resistant to crown gall is effective in a commercially important species (apple). The same approach should protect other fruit trees, nut trees, grapevines, cane berries, roses, chrysanthemum, and ornamental nursery plants. Crown gall is a serious problem worldwide; this disease causes millions of dollars of damage each year in fruit and nut orchards, vineyards, and nurseries. Other than our strategy, no effective means exists to prevent or cure crown gall. Because only rootstocks need protection from crown gall, fruiting wood grafted to gall-resistant rootstock does not need to be genetically engineered. This fact may alleviate cnsumer concerns regarding gentically modified foods because the fruit from these plants will not contain foreign genes. Because only gene fragments are needed to trigger gene silencing, which is responsible for the gall resistance trait, even the rootstocks do not contain intact foreign
genes. Thus, this technology is extremely safe, effective, and inexpensive.
Publications
- No publications reported this period
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