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
1997-04-25
1999-11-09
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
800288, 800298, 435 691, 435101, 435193, 4353201, 435468, 536 237, C12N 1582, C12N 1554, C12N 1531, C12P 1904, C12P 1918
Patent
active
059818387
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to plants genetically modified to increase the level of stored carbohydrates in the plant, particularly during periods of high sink activity and low source activity. The invention also relates to the genetic constructs used to produce the engineered plants and the method of producing the engineered plants.
BACKGROUND ART
The soluble storage carbohydrate found in plants, including sucrose, glucans, starch and fructans, are an important source of feed for animals, particularly grazing ruminants. These carbohydrates are stored non-structurally which makes them readily available for digestion by animals and therefore an important source of digestible energy.
During periods of high sink activity and low source activity, such as during a drought, the level of stored carbohydrates falls as the non-structural storage carbohydrates are mobilised for use in seed filling. The result of this mobilisation, particularly in relation to pasture grasses, is a significant loss of feed value to grazing ruminants due to the reduction in the levels of the stored carbohydrates. This reduction is caused by the enzymatic degradation of the stored carbohydrates. This enzymatic degradation is assisted by the fact that the stored carbohydrates generally have a low degree of polymerization. For example, as noted by Radojevic et al 1994, during the period from late spring to early autumn in southern Australia, the declining feed quality of the grasses causes a corresponding reduction in the lactation by dairy herds and necessitates the use of supplementary feeds. This decline in digestibility is associated with a decline in the level of soluble carbohydrates.
Perennial rye grass lines which accumulate high concentrations of soluble carbohydrates from late spring to early autumn do not suffer as large a decline in digestibility (Radojevic et al 1994). The result of this increased digestibility is a corresponding increase in milk production by dairy herds.
In addition to this, there are many pasture plants, such as white clever which do not possess any significant levels of stored carbohydrate.
There has, therefore, been a desire to develop methods for preventing the degradation of the stored carbohydrates during plant senescence and to increase the level of stored carbohydrates in pasture plants with low levels.
Glucosyltransferases of Streptococcus salivarius
It is known that many strains of Streptococcus salivarius and Streptococcus mutans, produce extracellular .alpha.-D-glucosyltransferase (Gtfs), an enzyme which catalyses the formation of glucan from sucrose. These Gtfs are also found in many other species of oral streptococci.
The Gtfs utilise the high free energy of the glycosidic bond of sucrose to synthesise glucans (Jacques N A, Giffard P M, 1991). Gtfs produce either soluble or insoluble products by transferring a glucose residue from sucrose to a growing glucan chain.
Gtfs which produce an insoluble product are generally considered to be primer-dependent (Walker G J, Jacques N A, 1987). These primer-dependent Gtfs require a dextran (.alpha.-(1.fwdarw.6)-linked glucan) as a receptor for polymerisation to proceed at an appreciable rate. In contrast, Gtfs that produce soluble products may be either primer-dependent or primer-independent. The genetic sequences for 10 gtf genes from a number of Streptococcus species have been ascertained (Gilmore K S, Russell R R B, Ferretti J J). All the Gtfs coded by these genes possess highly conserved putative signal sequences that lead to the secretion of these enzymes. The remainder of each protein is arbitrarily divided into two domains--the N-terminal two-thirds "catalytic domain" and the C-terminal one-third "glucan-binding domain".
S. salivarius ATCC 25975 has been shown to possess at least four different gtf genes (Giffard et al (1991); Giffard et al (1993)). Each of these genes codes for a highly hydrophilic monomeric glucosyltransferase that possesses unique enzymic properties. These Gtfs synthesize structurally different glucans fro
REFERENCES:
Streptococcus salivarius ATCC 25975 Possesses at Least Two Genes Coding for Primer-Independent Glucosyltransferases, Christine L. Simpson, et al., Infection and Immunity, Feb. 1995, pp. 609-621, Vo. . 63, No. 2.
Sequence of the gtfK gene of Streptococcus salivarius ATCC 25975 and evolution of the gtf genes of orgal streptococci, Philip M. Giffard, et al., Journal of General Microbiology (1993), 139, pp. 1511-1522.
Chemical Composition and in vitro Digestibility of Lines of Lolium perenne Selected for High Concentrations of Water-soluble Carbohydrate, I. Radojevic, et al., Aust. J. Agric. Res., (1994), 45, pp. 901-912.
Glucosyltransferases of Oral Streptococci, Nick Jacques, et al., Today's Life Science, Mar. 1991, 40-46.
Reprints from Reizer & Peterkofsky: Sugar Transport and Metabolism in Gram-Positive Bacteria, Published in 1987 by Ellis Horwood Ltd., Chichester, England, ISBN 0-7458-0024-6, Walker et al, pp. 39-68, Chapter 2.
Analysis of the Streptococcus downei gtfS Gene, Which Specifies a Glucosyltransferase That Synthesizes Soluble Glucans, N. A. Jacques, Keeta S. Gilmore, et al., Infection and Immunity, Aug. 1990, pp. 2452-2458, vol. 58, No. 8.
Molecular characterization of a cluster of at least two glucosyltransferase genes in Streptococcus salivarius ATCC 25975, Philip M. Giffard, et al., Journal of General Microbiology (1991), 137, pp. 2577-2593.
Cloning and Expression of Glycosyltransferase Activities from Streptococcus salivarius, L.J. Pitty, et al., Journal of Dental Research, Special Issue, 1989, vol. 68 : 1681-1682, Nov.
Membrane Perturbation by Cerulenin Modulates Glucosyltransferase Secretion and Acetate Uptake by Streptococcus salivarius, Nicholas A. Jacques, Institute of Dental Research, Journal of Microbiology (1983), 129, pp.3293-3302.
The glucosyltransferases of Streptococcus salivarius, Nicholas A. Jacques, Australian Dental Journal 1994; 39(2):111-114.
Sequence Analysis of the gtfB Gene from Streptococcus mutans, T. Shiroza, et al., Journal of Bacteriology, Sep. 1987, pp. 4262-4270, vol. 169, No. 9.
Extracellular Sucrose Metabolism by Streptococcus salivarius, N. A. Jacques, Institute of Dental Research, 1995, vol. 85, pp. 315-322, Dev. Biol. Stand.
Nucleotide Sequence of a Glucosyltransferase Gene from Streptococcus sobrinus MFe28, Joseph J. Ferretti, et al., Journal of Bacteriology, Sep. 1987, pp. 4271-4278, vol. 169, No. 9.
Fructan as a New Carbohydrate Sink in Transgenic Potato Plants, Ingrid M. van der Meer, at al., Gene Plant Cell, vol. 6, pp.561-570, Apr. 1994, American Society of Plant Physiologists.
Accumulation of Fructose Polymers in Transgenic Tobacco, Michael J. M. Ebskamp, et al., Biotechnology, vol. 12, pp. 272-275, Mar. 1994.
Table 1 -- Properties of the GTFs of Streptococcus salivarius ATCC 25975 May 1994.
Definition of a Fundamental Repeating Unit in Streptococcal Glucosyltransferase Glucan-binding Regions and Related Sequences, P. M. Giffard, et al., Journal of Dental Research, vol. 73, No. 6, pp. 1133-1141, 1994.
Kossmann et al. Progress Biotechnol. 10:271-278, 1995.
Simpson et al., Microbiology, vol. 141, pp. 1451-1460 (1995).
Giffard Philip Morrison
Jacques Nicholas Anthony
Simpson Christine Lynn
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