Plant protecting and regulating compositions – Compositions for preservation or maintenance of cut flowers
Reexamination Certificate
1999-08-20
2001-11-06
Lambkin, Deborah C. (Department: 1626)
Plant protecting and regulating compositions
Compositions for preservation or maintenance of cut flowers
C504S115000, C504S320000, C504S326000, C504S353000, C504S356000, C585S023000, C585S365000, C585S379000, C585S380000
Reexamination Certificate
active
06313068
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the regulation of plant physiology, in particular to methods for inhibiting the ethylene response in plants or plant products, in order to prolong their shelf life. The invention relates to prolonging the shelf life of cut flowers and ornamentals, potted plants (edible and non-edible), transplants, and plant foods including fruits, vegetables and root crops.
The present invention has three embodiments. The first embodiment relates to methods of minimizing impurities capable of reversibly binding to plant ethylene receptor sites during the synthesis of cyclopropene and its derivatives, in particular methylcyclopropene. Certain impurities produced during the manufacture of cyclopropene and its derivatives, in particular methylcyclopropene, have negative effects on treated plants. Therefore, when plants are treated with cyclopropene and its derivatives, in particular methylcyclopropene, made by using the methods of synthesis of the present invention, the negative effects of these impurities are avoided.
The second embodiment of the present invention relates to complexes formed from molecular encapsulation agents, such as cyclodextrin, and cyclopropene or its derivatives, such as methylcyclopropene, in addition to complexes formed from molecular encapsulation agents and cyclopentadiene or diazocyclopentadiene or their derivatives. These molecular encapsulation agent complexes provide a convenient and safe means for storing and transporting the compounds capable of inhibiting the ethylene response in plants. These molecular encapsulation agent complexes are important because the compounds capable of inhibiting the ethylene response in plants are reactive gases and therefore highly unstable because of oxidation and other potential reactions.
The third embodiment relates to convenient methods of delivering to plants the compounds capable of inhibiting their ethylene responses in order to extend shelf life. These methods involve contacting the molecular encapsulation agent complex with a solvent capable of dissolving the molecular encapsulation agent, thereby liberating the compound capable of inhibiting the ethylene response so it can contact the plant.
BACKGROUND OF THE INVENTION
The present invention generally relates to the regulation of plant growth and to methods of inhibiting ethylene responses in plants by application of cyclopropene, cyclopentadiene, diazocyclopentadiene or their derivatives, in particular methylcyclopropene. The present invention specifically relates to methods of synthesis and molecular encapsulation agent complexes, in addition to storage, transport and application of these gases that inhibit ethylene responses in plants.
Plant growth responses are affected by both internal and external factors. Internal control of plant processes are under the influence of genetic expression of the biological clocks of the plant. These processes influence both the extent and timing of growth processes. Such responses are mediated by signals of various types which are transmitted within and between cells. Intracellular communication in plants typically occurs via hormones (or chemical messengers) as well as other less understood processes.
Because communications in a plant are typically mediated by plant hormones, both the presence and levels of such hormones are important to specific plant cell reactions. The plant hormone that is most relevant to the present invention is ethylene, which has the capacity to affect many important aspects of plant growth, development and senescence. The most important effects of ethylene include processes normally associated with senescence, particularly fruit ripening, flower fading and leaf abscission.
It is well known that ethylene can cause the premature death of plants including flowers, leaves, fruits and vegetables. It can also promote leaf yellowing and stunted growth as well as premature fruit, flower and leaf drop.
Because of these ethylene-induced problems, very active and intense research presently concerns the investigation of ways to prevent or reduce the deleterious effects of ethylene on plants.
One major type of treatment used to mitigate the effects of ethylene employs ethylene synthesis inhibitors. These ethylene synthesis inhibitors reduce the quantity of ethylene that a plant can produce. Specifically, these ethylene synthesis inhibitors inhibit pyridoxal phosphate-mediated reactions and thereby prevent the transformation of S-adenosynimethione to 1-amino cyclopropane-1-carboxylic acid, the precursor to ethylene. Staby et al. (“Efficacies of Commercial Anti-ethylene Products for Fresh Cut Flowers”, Hort Technology, pp. 199-202, 1993) discuss the limitations of these ethylene synthesis inhibitors. Because ethylene synthesis inhibitors only inhibit a treated plant's production of ethylene, they do not suppress the negative effects of ethylene from environmental sources. These environment sources of ethylene exist because ethylene is also produced by other crops, truck exhaust, ethylene gashing units and other sources, all of which can affect a plant during production, shipment, distribution and end use. Because of this, ethylene synthesis inhibitors are less effective than products that thwart a plant's ethylene responses. For a discussion of the ethylene response in plants, see U.S. Pat. No. 3,879,188.
The other major type of treatment used to mitigate the effects of ethylene employs blocking the receptor site that signals ethylene action. One of the best known compounds for inhibiting the ethylene response in plants, as well as preventing the deleterious effects from environmental sources of ethylene, is silver thiosulfate (“STS”). An example of a commercial STS product is SILFLOR solution, available from Floralife, Inc., Burr Ridge, Ill. STS is very effective in inhibiting the ethylene response in plants and has been used because it moves easily in the plant and is not toxic to plants in its effective concentration range. STS can be used by growers, retailers and wholesalers as a liquid that is absorbed into the stems of the flowers. While STS is highly effective, it has a serious waste disposal problem. It is illegal to dispose of the silver component of STS by conventional means, such as by using a laboratory sink, without first pretreating the STS to remove the silver. It is also illegal to spray STS on potted plants. Consequently because of this disposal problem which is typically ignored by growers, STS is now almost exclusively utilized only by growers. Therefore, there is a great desire among postharvest physiologists to find alternatives to STS. To the knowledge of the present inventors, the only commercially acceptable replacements for STS are cyclopropene, cyclopentadiene, diazocyclopentadiene and their derivatives.
Many compounds such as carbon dioxide which block the action of ethylene diffuse from the ethylene receptor or binding site over a period of a few hours. Sisler & Wood, Plant Growth Reg. 7, 181-191, 1988. While these compounds may be used to inhibit the action of ethylene, their effect is reversible and therefore they must be exposed to the plant in a continuous manner if the ethylene inhibition effect is to last for more than a few hours. Therefore, an effective agent for inhibiting the ethylene response in plants should provide an irreversible blocking of the ethylene binding sites and thereby allow treatments to be of short duration.
An example of an irreversible ethylene inhibiting agent is disclosed in U.S. Pat. No. 5,100,462. However, the diazocyclopentadiene described in that patent is unstable and has a strong odor. Sisler et al., Plant Growth Reg. 9, 157-164, 1990, showed in a preliminary study that cyclopentadiene was an effective blocking agent for ethylene binding. However, the cyclopentadiene described in that reference is also unstable and has a strong odor.
U.S. Pat. No. 5,518,988 discloses the use of cyclopropene and its derivatives, including methylcyclopropene, as effective blocking agents for ethylene b
Daly James
Kourelis Bob
AgroFresh, Inc.
Lambkin Deborah C.
Sonnenschein Nath & Rosenthal
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