Multicellular living organisms and unmodified parts thereof and – Method of introducing a polynucleotide molecule into or... – The polynucleotide alters carbohydrate production in the plant
Patent
1996-03-08
2000-05-23
Fox, David T.
Multicellular living organisms and unmodified parts thereof and
Method of introducing a polynucleotide molecule into or...
The polynucleotide alters carbohydrate production in the plant
800278, 800286, 800287, 800294, 800298, 8003172, 435101, 435193, 4353201, 435419, 435468, 435469, 536 236, 536 245, C12N 1529, C12N 1584, C12N 1582, C12P 1904, A01H 500
Patent
active
060667826
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a combination of DNA sequences which, in transgenic plant cells and plants, results in a modification of the starch formed in the cells. The invention further relates to a process for the production of genetically modified plants which are modified in respect of the physical and chemical properties of the starch formed in comparison with the naturally formed starch due to the expression of artificially introduced DNA sequences, to the plant cells and plants obtainable by this process and to the modified starch obtainable from these plants.
BACKGROUND OF THE INVENTION
Together with oils, fats and proteins, polysaccharides such as starch are the essential renewable raw materials from plants.
A decisive obstacle to the use of renewable raw materials as industrial raw materials is the lack of materials whose form, structure or other physicochemical parameters precisely meet the requirements of the chemical industry. Two particular requirements of a raw material suitable for industrial use are that it is available in high purity and that it has a uniform chemical structure. The latter is important for ensuring that reactions proceed homogeneously during processing.
Although starch is a polymer made up of chemically uniform basic structural units, namely glucose molecules, it is a complex mixture of very varied molecular forms which differ in their degree of polymerization and the occurrence of branches in the glucose chains. The degree of branching determines inter alia the physicochemical properties of the starch in question and hence also its suitability for a very wide variety of applications. A distinction is made in particular between amylose starch, which is an essentially unbranched polymer made up of .alpha.-1,4-linked glucose molecules, and amylopectin starch, which in turn is a complex mixture of variously branched glucose chains. The branches arise from the occurrence of additional .alpha.-1,6 linkages.
In typical plants for starch production, such as maize or potato for example, the two forms of starch occur in proportions of about 25 parts of amylose to 75 parts of amylopectin.
To adapt the starch raw material to the different industrial applications, i.e. to vary its physicochemical properties, it is necessary inter alia to be able to influence the degree of branching of the starch.
With regard to the suitability of a basic material such as starch for its use in the industrial sector, it therefore seems desirable to provide processes for the production of amylogenic plants synthesizing a starch which is modified in comparison with the naturally occurring starch.
It is especially desirable to modify starch so that it has a modified degree of branching, e.g. a decrease or increase in the degree of branching, thereby forming a more uniform starch with a higher or lower amylose content.
An example of another property of interest for the industrial use of starch is the content of phosphate groups. Phosphate-containing starch has a broad application in a very wide variety of fields, e.g. in paper manufacture, in textile manufacture, as adhesives, in the food sector or in medicine. Furthermore, starch phosphate derivatives are suitable for use as emulsifiers. As the starch which occurs naturally in the majority of amylogenic plants contains only a very small proportion of phosphate groups, a specific exception here being starch formed in underground organs such as e.g. roots or potato tubers, phosphate groups have hitherto usually been introduced by means of chemical processes. To avoid the additional outlay on costs and time associated with such processes for the introduction of phosphate groups into starch, it seems desirable to provide processes which make it possible to modify plants so that they produce a starch which is modified in such a way as to have an increased content of phosphate groups.
As regards the degree of branching of starch, it is already known that for certain plant species, for example maize, varieties containing only amylopectin can be produced
REFERENCES:
Journal Of Biological Chemistry, vol. 268, No.2, Jan. 15, 1993 Baltimore, MD US pp. 1391-1396 Takaha, T., et al. `Disproportionating enzyme (4-alpha-glucanotransferase; EC 2.4.1.25) of potato. Purification, molecular clonging, and potential role in starch metabolism`.
Mol. Gen. Genet., vol.225, 1991 pp. 289-296 Visser, R.G.F., et al. `Inhibition of the expression of the gene for granule-bound starch synthase in potato by antisense constructs`.
Kossmann et al. 1995. pp. 271-278 In: Carbohydrate Bioengineering, Peterson et al. (eds), Elsevier Science B.V.: Amsterdam.
Napoli et al. 1990. Plant Cell 2 : 279-289.
Smith et al. 1988. Nature 334: 724-726.
Kossmann Jens
Virgin Ivar
Fox David T.
Hoechst Schering AgrEvo GmbH
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