Chemistry: molecular biology and microbiology – Treatment of micro-organisms or enzymes with electrical or... – Modification of viruses
Patent
1993-11-24
1996-05-14
Robinson, Douglas W.
Chemistry: molecular biology and microbiology
Treatment of micro-organisms or enzymes with electrical or...
Modification of viruses
800255, 800DIG57, 4352404, C12N 1500, A01H 104
Patent
active
055166687
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD
This invention relates to a method for decreasing a seed storage protein, thereby obtaining seeds with reduced amount of the protein. This invention also relates to a method for transforming plants.
PRIOR ART
In seeds of higher plants, proteins are contained in an amount of 20-30% by weight in case of beans, and in an amount of about 10% by weight in case of cereals, based on dry weight. Among the proteins in seeds, 70-80% by weight are storage proteins. Particularly, in rice seeds, about 80% by weight of the seed storage proteins is glutelin which is only soluble in dilute acids and dilute alkalis. The remainders are prolamin (10-15% by weight) soluble in organic solvents and globulin (5-10% by weight) solublilized by salts.
Seed storage proteins are important as a protein source in foods, so that they have been well studied from the view points of nutrition and protein chemistry. As a result, in cereals, storage protein genes of maize, wheat, barley and the like have been cloned, amino acid sequences of the proteins have been deduced from the nucleotide sequence, and regulatory regions of the genes have been analyzed.
The cDNA of glutelin which is a seed storage protein in rice has been cloned and complete primary structure of the protein has been determined by sequencing the cDNA. The gene of this protein has been isolated by using the cDNA as a probe (Japanese Laid-open Patent Application (Kokai) No. 63-91085).
In order to clarify the function of the 5' region (glutelin promoter region) of the gene fragment originated from nucleus, a fused gene comprising the glutelin promoter and chloramphenicol acetyltransferase (CAT) gene as a reporter gene was introduced to tobacco plants using Agrobacterium. CAT assay of these transformed tobacco plants revealed that rice glutelin promoter is expressed specifically in endosperm in seeds and is expressed specifically in maturation phase of seeds (Okita et al., Plant Molecular Biology, 14, 41-50 (1989).
For rice grains to be processed, it is demanded that protein content be small. In case of rice used for preparing fermented alcoholic beverage, this is attained by well refining the rice, thereby removing the proteins in the peripheral portion of endosperm which contains proteins in large amounts. In producing rice starch, in order to promote the purity, proteins are removed by treatments with alkalis, surfactants and ultrasonication.
Protein contents in rice grains also influence the taste of the rice. Rice grains with good taste have low contents of proteins. Rice varieties with low contents of proteins have been developed by the conventional cross-breeding or by mutation-breeding.
By virtue of the developments of plant tissue culture techniques and of techniques for introduction of genes, production of transformed plants have been reported. As for plants belonging to the family Gramineae, introduction of a foreign gene by treating protoplasts isolated from cultured cells with polyethylene glycol (Japanese Laid-open Patent Application (Kokai) No. 63-287485; and introduction of a foreign gene by applying electric pulses (Japanese Laid-open Patent Application (Kokai) No. 1-181791) have been reported.
As the promoter for expressing a foreign gene in transformed rice plants, in many cases, 35S promoter of cauliflower mosaic virus (CaMV) is used.
It is known that the function of an RNA such as a mRNA carrying the information of protein synthesis is suppressed by an RNA which has a nucleotide sequence complementary to the aforementioned RNA. Such an RNA is collectively referred to as antisense RNA. Researches for artificially producing antisense RNAs by employing gene recombination techniques are now being made.
For example, a petunia having a color different from that of wild type petunia has been provided by preparing a transformed petunia which produces an antisense RNA of chalcone synthetase concerning the synthesis of flower pigments (European Patent Publication No. 341,885). Further, tomato fruits having longer shelf life than wild type tomatoe
REFERENCES:
Larkins et al. (1985) J Cell Biochem Suppl. O (9 part C):264.
Smith et al. (1988) Nature 324: 724-726.
Leisy et al. (1989) Plant Mol Biol 14:41-50.
van der Krol et al. (1988) Nature 333:866-869.
Okita et al. (1989) J Biol Chem 264(21):12573-12581.
Okamura et al. (1986) Proc Natl Acad Sci USA 83:8240-8244.
Shimamoto et al. (1989) Nature 338: 274-276.
Japan Tobacco Inc.
McElwain Elizabeth F.
Rice Breeding Research Laboratories
Robinson Douglas W.
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