Plant protecting and regulating compositions – Compositions for preservation or maintenance of cut flowers
Reexamination Certificate
2001-02-20
2002-04-02
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Compositions for preservation or maintenance of cut flowers
C504S357000
Reexamination Certificate
active
06365549
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to methods of blocking ethylene responses in plants and plant materials, and particularly relates to methods of inhibiting various ethylene responses including plant maturation and degradation by applying cyclopropene derivatives and compositions thereof to plants.
BACKGROUND OF THE INVENTION
Ethylene is known to mediate a variety of growth phenomena in plants. See generally Fritz et al. U.S. Pat. No. 3,879,188. This activity is understood to be achieved through a specific ethylene receptor in plants. Many compounds other than ethylene interact with this receptor: some mimic the action of ethylene; others prevent ethylene from binding and thereby counteract its action.
Many compounds that block the action of ethylene do so by binding to the ethylene binding site. Unfortunately, they often diffuse from the binding site over a period of several hours. See E. Sisler and C. Wood,
Plant Growth Reg.
7, 181-191 (1988). These compounds may be used to counteract ethylene action. A problem with such compounds, however, is that exposure must be continuous if the effect is to last for more than a few hours.
Photoaffinity labeling has been used in biological studies to label binding sites in a permanent manner: usually by generating a carbene or nitrene intermediate. Such intermediates are very reactive and react rapidly and indiscriminately with many things. A compound already bound, however, would react mostly with the binding site. In a preliminary study, it was shown that transcyclooctene was an effective blocking agent for ethylene binding. See E. Sisler et al.,
Plant Growth Reg.
9, 157-164 (1990). Methods of combating the ethylene response in plants with diazocyclopentadiene and derivatives thereof are disclosed in U.S. Pat. No. 5,100,462 to Sisler et al. U.S. Pat. No. 5,518,988 to Sisler et al. describes the use of cyclopropenes having a C
1
to C
4
alkyl group to block the action of ethylene.
Notwithstanding these efforts, there remains a need in the art for improved plant maturation and degradation regulation.
SUMMARY OF THE INVENTION
Methods of inhibiting an ethylene response in a plant are disclosed herein. According to the present invention, one such method comprises applying to the plant an effective ethylene response-inhibiting amount of a cyclopropene derivative or a composition thereof described further in detail herein. Long-chain cyclopropene derivatives are particularly preferred as described below.
Another aspect of the present invention is a method of blocking ethylene receptors in plants by applying to the plants an effective ethylene receptor-blocking amount of a cyclopropene derivative or a composition thereof.
Also disclosed is a method of inhibiting abscission in a plant, comprising applying to the plant an effective abscission-inhibiting amount of a cyclopropene derivative or a composition thereof.
Also disclosed is a method of prolonging the life of a cut flower, comprising applying to the cut flower an effective life-prolonging amount of a cyclopropene derivative or a composition thereof.
Also disclosed is a method of inhibiting the ripening of a harvested fruit, comprising applying to the harvested fruit an effective inhibiting amount of a cyclopropene derivative or a composition thereof.
Also disclosed is a method of inhibiting the ripening of a harvested vegetable, comprising applying to the harvested vegetable an effective inhibiting amount of a cyclopropene derivative or a composition thereof.
The methods described herein may be carried out in a number of suitable manners, such as by contacting the plant with a cyclopropene derivative or a composition thereof, whether in solid, liquid, or gaseous form, or by introducing the plant, cut flower, picked fruit or picked vegetable into an atmosphere infused with the cyclopropene derivative or a composition thereof. These and other suitable methods of application are discussed in detail below.
Also disclosed is the use of a cyclopropene derivative as described herein for the preparation of an agricultural composition for carrying out any of the methods described above.
DETAILED DESCRIPTION OF THE INVENTION
Cyclopropene derivatives which may be used to carry out the present invention are defined by Formula I:
wherein:
n is a number from 1 to 4. Preferably n is 1 or 2, and most preferably n is 1.
R is a saturated or unsaturated, linear or branched-chain, unsubstituted or substituted, C
5
to C
20
alkyl, alkenyl, or alkynyl.
The terms “alkyl”, “alkenyl”, and “alkynyl”, as used herein, refer to linear or branched alkyl, alkenyl or alkynyl substituents. The terms should be interpreted broadly and may include compounds in which one or more of the carbons in one or more of the R groups is replaced by a group such as ester groups, nitriles, amines, amine salts, acids, acid salts, esters of acids, hydroxyl groups, halogen groups, and heteroatoms selected from the group consisting of oxygen and nitrogen or where such chains include halogen, amino, alkoxy, carboxy, alkoxycarbonyl, oxycarbonylalkyl, or hydroxy substituents. Thus, the resulting R groups can contain, for example, hydroxyl, ether, ketone, aldehyde, ester, acid, acid salt, amine, amine salt, amide, oxime, nitrile, and halogen groups.
Cyclopropene derivatives which may be used to carry out the present invention may be prepared by various methods known to those skilled in the art. For example, the reaction of a bromo-olefin with dibromocarbene gives a tribromocyclopropane, which can be converted to the cyclopropene with methyllithium or other organolithium compounds as shown. (see Baird, M. S.;
Hussain, H. H.; Nethercott, W;
J. Chem. Soc. Perkin Trans.
1, 1986, 1845-1854 and Baird, M. S.; Fitton, H. L.; Clegg, W; McCamley, A.;
J. Chem. Soc. Perkin Trans.
1, 1993, 321-326).
The bromo-olefins can be prepared by standard methods.
Additionally, 3,3-disubstituted cyclopropenes can be prepared using methods described by N. I. Yakushkina and I. G. Bolesov in
Dehydrohalogenation of Monohalogenocyclopropanes as a Method for the Synthesis of Sterically Screened Cyclopropenes,
R
USSIAN
J.
OF
O
RGANIC
C
HEM
. 15:853-59 (1979). Furthermore, a 1,1-disubstituted olefin can also react with dibromocarbene to give a dibrominated intermediate. This can be reduced with zinc to the mono-brominated cyclopropane. Elimination of the bromide with base gives the cyclopropene (see Binger, P.;
Synthesis
1974, 190).
Cyclopropene can be deprotonated with a strong base such as sodium amide in liquid ammonia and alkylated with an alkyl halide or other alkylating agent to give a substituted cyclopropene (reference: Schipperijn, A. J.; Smael, P.;
Recl. Trav. Chim. Pays
-
Bas,
1973, 92, 1159). The lithium salt of substituted cyclopropenes, generated from the cyclopropene or by reaction of the tribromocyclopropane with an alkyllithium, can be alkylated to give new cyclopropene derivatives.
Compounds according to the present invention can also be obtained from a malonate derivative as shown.
Methyl sterculate was formed by the procedure of Gensler et. al. (Gensler, W. J.; Floyd, M. B.; Yanase, R.; Pober, K. W.
J. Am. Chem. Soc.,
1970, 92, 2472).
The addition of a diazo compound to an acetylene is another method that can be used for the synthesis of cyclopropenes (Mueller, P.; Cranisher, C;
Helv. Chim. Acta
1993, 76, 521). Alternatively, the commercially available ethyl diazo acetate can be added to the acetylene to give the compound:
with R′″ being ethyl. This compound can be hydrolyzed to the carboxylic acid, and reacted with oxalyl chloride to give the acid chloride. The acid chloride can then be reacted with an alcohol to give the ester. In the foregoing synthesis routes, R
1
-R
4
are as described above for R.
Agricultural compositions comprising the compounds defined by Formula (I) described above are also encompassed by the invention. Preferably the compositions comprise between a lower limit of 0.005, 5, 10, 20 or 30% and an upper limit of 70, 80, 90, 95 or 99% by weight of the active com
Clardy S. Mark
Myers Bigel Sibley & Sajovec P.A.
North Carolina State University
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