Granted patent and applications filed by Syngenta (formerly Novartis)
According to the applicants the necrosis seen in some plants, i.e. Gramineae, upon Agrobacterium exposure is a programmed cell death that is different from the passive death experienced during oxidative browning and exposure to toxins. It is an active process in which the cells undergo morphological changes in part as a result of de novo gene expression and DNA cleavage.
The patents and patent applications disclose the use of physical and chemical methods for inhibiting Agrobacterium-induced necrosis (AIN). Heat shock treatment is one of the physical methods and among the chemical methods;chemical compounds are used as inhibiting agents of AIN. Nucleotide sequences such as p35 and iap (see below) stably or transiently expressed in the cell to be transformed also inhibit AIN. In addition, the applicants teach the use of Agrobacterium strains that are less likely to induce necrosis in the transformed tissue.
Specific Patent Information
Patent Number | Title, Independent Claims and Summary of Claims | Assignee | ||||||||||||||||||
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US 6162965
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Title – Plant transformation methods
United States patent US 6162965 claims several methods to inhibit AIN in plants:
The patent also claims methods for inhibiting AIN in Gramineae in general and in maize in particular. Besides the methods mentioned above, gramineaceous plants and maize may be cultured in a necrosis inhibiting medium containing an inhibitor of ethylene or ethylene biosynthesis. |
Syngenta | ||||||||||||||||||
US 2002/88029 AA
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Title – Plant transformation methods
United States application US 2002/88029 is a continuation of application No. 09/089,111, which is now patent US 6162965 described above. The additional elements in this application include a method to select an Agrobacterium strain with reduced necrosis-inducing capacity from a population of regenerable plant cells from the family Gramineae. Further, the application also claims the Agrobacterium strain with reduced or eliminated production of the necrosis factor, obtained through the selection process or through genetic manipulation. Finally, a method is claimed to transform regenerable cells from the family Gramineae using such strains. The “Agrobacterium necrosis factor” is disclosed as “the heat labile factor observed in concentrated supernatant capable of inducing necrosis, e.g., programmed cell death, in maize embryos.” The application discloses sequences cloned into three BAC vectors associated with affects on cell death. The sequences are reported to have homology with virB1, xylA-xylB and acvB respectively. It’s not clear if the Agrobacterium strain referred to in claim 13 is required to reduce or eliminate the expression of one or all of these sequences since none of these sequences are clearly identified as “the” factor. The genetic structure of a strain having the properties recited in the claims is not disclosed nor is a way of identifying such a strain disclosed. |
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AU 735472 B
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Title – Plant transformation methods
The methods for inhibiting AIN claimed in the granted Australian patent are similar to the ones claimed in the United States patent. However, the group of chemical inhibitors additionally includes gibberellin antagonists and phosphatase inhibitors. Also, the nucleotide sequences whose products inhibit AIN are not limited to specific genes, but encode any mRNA or protein inhibiting AIN. Furthermore, unlike the United States patent, the Australian patent does not claim transformation of Gramineae or maize in particular. |
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WO 1998/54961 A2
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Title – Plant transformation methods
The claims as filed in the PCT application are broader in scope than the granted claims of both the Australian and the US patents. For example, one claim broadly recites “conditions which inhibit AIN” without specifying details of suitable conditions. In another claim the culture medium for the plant cell or tissue contains a chemical inhibitor without defining what sort of chemical. A couple of claims of the European application make reference to the use of an Agrobacterium strain that does not induce significant levels of necrosis. The Agrobacterium strain has been modified to reduce or eliminate expression of a necrosis factor. This strain of Agrobacterium may be used for transforming a totipotent Gramineae cell. |
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Remarks |
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Note: Patent information on this page was last updated on 3 March 2006.