Multicellular living organisms and unmodified parts thereof and – Plant – seedling – plant seed – or plant part – per se – Higher plant – seedling – plant seed – or plant part
Reexamination Certificate
1998-10-19
2001-02-06
Nelson, Amy J. (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Plant, seedling, plant seed, or plant part, per se
Higher plant, seedling, plant seed, or plant part
C435S320100, C435S419000, C536S023200, C536S023600, C800S283000, C800S286000
Reexamination Certificate
active
06184449
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the field of compositions and methods for inhibiting the enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase in rose thereby prolonging the shelf-life of cut flowers as well as reducing leaf yellowing and petal abscission during shipping and storage.
A variety of factors cause wilting and natural abscission in flowers, particularly after a cutting of the plant or when flowers have been removed from the plant. Such factors include increased oxygen levels, wounding, chemical stress, and the plant's own production of ethylene. Of these factors, the plant's production of ethylene, has been shown to play a key role in natural senescence, the degenerative process which generally leads to controlled cell death in plants, but also in the degradation of flowers after they have been cut.
Ethylene, in all higher plants, is important to plant growth and development from seed germination, seedling growth to flowering and senescence (Abeles, F. B. et al. (1992), In:
Ethylene in Plant Biology.
Eds. Abeles, F. B. et al., Academic Press, New York, pp 285-291 and 1-13; Yang, S. F. et al. (1984),
Annu. Rev Plant Physiol:
35, 155-189). Ethylene production in plants can also be associated with trauma induced by mechanical wounding, chemicals, stress (such as produced by temperature and water amount variations), and by disease. Hormones can also stimulate ethylene production. Such ethylene, also sometimes called “stress ethylene”, can be an important factor in storage effectiveness for plants. Moreover, exposure of plant tissue to a small amount of ethylene often may be associated with increased production of ethylene by other adjacent plants. This autocatalytic effect may be often associated with losses in marketability of plant material during storage and transportation (Abeles et al., supra; Yang et al., supra).
The ethylene biosynthetic pathway in plants was established by Adams and Yang (Adams D. O., et al., (1979)
Proc. Nat'l Acad Sci USA
76: 170-174)). The first step involves the formation of S-adenosyl-L-methionine (AdoMet) from methionine by S-adenosyl-L-methionine synthetase. AdoMet is then converted into 1-aminocyclopropane-1-carboxylate (ACC), the direct precursor of ethylene in higher plants. This conversion is catalyzed by ACC synthase (S-adenosyl-L-methionine methyl thioadenosine-lyase, EC4.4.1.14), the rate limiting step in the ethylene biosynthetic pathway. (See also Kionka C., et al., (1984) Planta 162:226-235; Amrhein N. et al., (1981)
Naturwissenschaften
68: 619-620; Hoffman N. E., et al., (1982) Biochem Biophys Res Commun 104:765-770).
Knowledge of the biosynthetic pathway for ethylene formation has been fundamental in developing strategies for inhibiting ethylene production in plants. One approach has been to use chemical inhibitors to inhibit the synthesis or activity of ethylene, two of the most common being aminoethoxyvinylglycine and aminooxyacetic acid (Rando, R. R., 1974, Science, 185, 320-324 and in Ethylene in Plant Biology, (Abeles, F. B., et al., eds. Academic Press, p. 285)). However, chemical methods find limited use because such methods are expensive and the beneficial effect they provide is generally only short-lived.
A second approach has been to over express ACC deaminase, an enzyme which metabolizes ACC, thereby eliminating an intermediate in the biosynthesis of ethylene (Klee, et al., (1991) Cell 3: 1187-1193) (See also Theologis, A., et al. (1993), Cellular and Molecular Aspects of the Plant Hormone Ethylene, p. 19-23). Because ACC deaminase is a bacterial enzyme, it is heterologous, and thus, external to the plant. Thus, it is unlikely that this approach will yield a modification that will be stable from generation to generation.
Yet another approach involves attempts to genetically inhibit the production of the enzymes involved in the biosynthesis of ethylene or to inhibit the biosynthesis of the enzymes directly. This approach has the advantage of not only altering the way the plant itself functions irrespective of external factors but also of presenting a system which reproduces itself, that is, the altered plant's progeny will have the same altered properties for generations to come.
Initial efforts to better understand the enzymes which catalyze the reactions in the biosynthesis of ethylene have involved the identification and characterization of the genes encoding for AdoMet synthetase, ACC synthase, and ACC oxidase (See also Kende H., 1993, Annu Rev Plant Physiol Mol Biol 44:283-307). Some of the genes encoding for ACC synthase have been identified for a number of plants. For instance, ACC synthase sequences have been identified for zucchini (Sato T., et al., (1989)
Proc. Natl Acad Sci USA
86:6621-6625), winter squash (Nakajima, N., et al., (1990)
Plant Cell Physiol
31:1021-1029), tomato (Van Der Straeten, D., et al., (1990)
Proc Natl Acad Sci USA
87:4859-4863); (Rottmann, W. H., et al., (1991)
J Mol Biol
222:937-961), apple (Dong, J. G., et al., (1991)
Planta
185:38-45), mung bean (Botella, J. R., et al., (1992a)
Plant Mol Biol
20:425-436; Botella, J. R., et al., (1993) Gene 123: 249-253; Botella, J. R., et al., (1992b)
Plant Mol Biol
18: 793-797); Kim, W. T., et al., (1992)
Plant Physiol
98:465-471), carnation (Park, K. Y., et al., (1992)
Plant Mol. Biol.,
18, 377-386),
Arabidopsis thaliana
(Liang, X., et al., (1992)
Proc Natl Acad Sci USA
89:11046-11050; Van Der Staeten, D., et al., (1992) Proc Natl Acad Sci USA 89:9969-9973), tobacco (Bailey, B. A., et al., (1992)
Plant Physiol
100: 1615-1616), rice (Zarembinski, T. I., et al., (1993)
Mol Biol Cell
4: 363-373), mustard (Wen, C. M., et al., (1993)
Plant Physiol
103:1019-1020), orchid (O'Neill, S. D., et al., (1993) Plant Cell 5: 419-432), broccoli (Pogson, B. J., et al., (1995)
Plant Physiol
108:651-657), and potato (Schlagnhaufer, C. D., et al.. (1995)
Plant Mol. Biol.
28:93-103).
That ACC synthase is involved in the ethylene pathway is confirmed by the fact that increased levels of ACC synthase mRNA correlate with an increased activity of ACC synthase in plants during fruit ripening and flower senescence. Similar correlation is also observed in response to exogenous signals caused either by wounding or due to treatment with hormones such as auxin, cytokinin and ethylene. Interestingly, the expression of different classes of ACC synthase occurs from a variety of signals in many plants, e.g. four different ACC synthase genes have been shown to be differentially expressed in tomato fruit, cell cultures, and hypocotyls during ripening, wounding, and auxin treatment (Olson, D. C., et al (1991) Proc. Natl. Acad. Sci. USA 88:5340-5344; and Yip, W. K., (1992) Proc. Natl. Acad. Sci. USA 89:2475-2479). Differential expression of two ACC synthase genes has also been observed in winter squash during wounding or by auxin (Nakajima, et al. (1990) Plant Cell Physiol, 31; 1021-29 and (1991) Plant Cell Physiol, 32; 1153-63). Similar differential regulation of expression ACC synthase genes takes place in carnation flowers by wounding or during senescence (Park, K. Y., et al., (1992)
Plant Mol. Biol.,
18, 377-386). The evolution of ACC synthase genes into a multigene family that responds differentially during plant development or in response to stimuli external to the plant (Rottmann, W. H., et al., (1991)
J Mol Biol
222:937-961) may be a reflection of the importance of ethylene in plants. (See also Slater, A., et al., (1985) Plant Mol Biol 5:137-147). (Smith, C. J. S., et al., (1986) Planta 168; 94-100 and Smith, C. J. S., et al. (1988) Nature 334;724-26). (Hamilton, A. J., et al., (1990) Nature 346:284-286; Köck, M., et al., (1991) Plant Mol Biol 17:141-142).
The discovery of the foregoing and of other properties has lead to an understanding that it may be desirable to attempt to genetically alter the production of ethylene in plants. This approach, however, may be considered in some ways delicate. Elimination of ethylene is not a desired result as in many instances it will kill the plan
Nelson Amy J.
Santangelo Law Offices P.C.
Tagawa Greenhouses, Inc.
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