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
2001-12-20
2004-08-03
Fox, David T. (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
C800S264000, C800S270000, C800S275000
Reexamination Certificate
active
06770801
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to corn (
Zea mays
L.) seed and grain having a significantly higher oleic acid content by virtue of heritable genes for increased oil and oleic acid content and/or lowered levels of linoleic acid. The present invention also relates to the production of high oil, high oleic grain, plants and plant parts grown from such grain and uses of such improved grain.
TECHNICAL BACKGROUND OF THE INVENTION
Corn oil is comprised primarily of even-numbered carbon chain fatty acids. The distribution of fatty acids in typical corn oil is approximately 12% palmitic acid (16:0), 2% stearic acid (18:0), 25% oleic acid (18:1), 60% linoleic acid (18:2), and 1% linolenic acid (18:3). Palmitic and stearic acids are referred to as saturated fatty acids because their carbon chains contains only single bonds and the carbon chain is “saturated” with hydrogen atoms. Oleic, linoleic, and linolenic acids contain one, two, and three double bonds respectively, and are referred to as unsaturated fatty acids. Fatty acids in corn oil nearly always occur esterified to the hydroxyl groups of glycerol, thus forming triglycerides. Approximately 99% of refined corn oil is made up of triglycerides; Corn Oil, Corn Refiners Association, Inc., 1001 Connecticut Ave., N.W., Washington, D.C. 20036, 1986, 24 pp.
When exposed to air, unsaturated fatty acids are subject to oxidation which causes the oil to have a rancid odor. Oxidation is accelerated by high temperatures, such as in frying conditions. The rate of oxidation is proportional to the number of double bonds in the fatty acids. Thus, linoleic acid with two double bonds is more unstable than oleic acid which has only one double bond. Oxidation reduces the shelf life of products containing corn oil because of the oil's high proportion of linoleic acid. Corn oil and products containing corn oil are often packaged under nitrogen in special packaging materials such as plastic or laminated foil, or are stored under refrigeration to extend their shelf life. These extra measures to reduce oxidation and subsequent rancidity add considerable cost to products containing corn oil.
Another measure to reduce the effects of oxidation on corn oil is to chemically hydrogenate the oil. This commercially important process by which hydrogen is added to double bonds of unsaturated fatty acids changes the physical properties of the oil and extends the shelf life of products containing corn oil. Hydrogenated vegetable oils are used to make margarine, salad dressings, cooking oils, and shortenings, for example. Approximately half a billion pounds, or roughly 40-50% of corn oil produced in the U.S. is used for cooking and for salad oils; Fitch, B., JAOCS, 1985, Vol. 62, no. 11, pp. 1524-31. Production of a more stable oil by genetic means would clearly have value by reducing or eliminating the time and input costs of chemical hydrogenation.
In addition to the economic factors associated with chemical hydrogenation of corn oil, there are human health factors that favor the production of a natural high oleic oil. During the hydrogenation process, double bonds in fatty acids are completely hydrogenated or are converted from the cis configuration to the trans configuration. Cis double bonds cause a fatty acid molecule to bend, which impairs crystallization and keeps the oil liquid at room temperature. During hydrogenation, cis bonds are straightened into the trans configuration, causing the oil to harden at room temperature. Recent studies on the effect of dietary trans fatty acids on cholesterol levels show that the trans isomer of oleic acid raises blood cholesterol level at least as much as saturated fatty acids, which have been know for some time to raise cholesterol in humans; Mensink, R. P. and B. K. Katan, N. Engl. J. Med., 1990, 323:439-45. Furthermore, the studies show that the undesirable low density lipoprotein level increases and the desirable high density lipoprotein level decreases in response to diets high in trans fatty acids. Large amounts of trans fatty acids are found in margarines, shortenings, and oils used for frying; the most abundant trans fatty acid in the human diet is the trans isomer of oleic acid, elaidic acid. A natural high oleic corn oil, which does not contain elaidic acid, will benefit consumers in general, and will particularly benefit those people who control their cholesterol level through their diet.
The human diet could also be improved by reducing saturated fat intake. Much of the saturated fat in the human diet comes from meat products. Poultry and swine diets often contain animal fat, which is high in saturated fatty acids, as an energy source. Non ruminant animals such as these are very susceptible to tissue fatty acid alteration through dietary modification; M. F. Miller, et al., J. Anim. Sci., 1990, 68:1624-31. A large portion of animal feed rations is made up of corn, which typically contains only about 4% oil. By replacing some or all of the supplemental animal fat in a feed ration with the oil present in high oil corn varieties, which contain up to 10% oil, it will be possible to produce meat products having less saturated fats. Feeding trials in which swine were fed diets high in oleic acid show that the amount of oleic acid deposited in adipose tissue can be raised substantially without adversely influencing the quality of the meat; M. F. Miller, et al., supra; L. C. St. John, et al., J. Anim. Sci., 1987, 64:1441-47. The degree of saturation of the fatty acids comprising an oil determines whether it is liquid or solid. In these studies, the animal diets high in oleic acid led to meat quality that was acceptable to the meat processing industry because of the low level of polyunsaturated fatty acids. Therefore, it can be extended that a feed ration containing high oleic, high oil corn would be preferable to one containing high oil corn which contains a high level of linoleic acid. Consumption of monounsaturated fatty acids decreases the LDL level without affecting the HDL level; Mattson, F. R., and S. M. Grundy, J. Lipid Res., 1985, 26:194. The HDL portion is responsible for removal of cholesterol from the body; L. C. St. John, supra. Processed meats produced from animals fed diets containing high oil, high oleic corn will be more healthful in the human diet.
The corn kernel is a product of double fertilization; Kiesselbach, T. A., 1980, The Structure and Reproduction of Corn, University of Nebraska Press. This means that both the diploid embryo (giving rise to the germ and seedling) and the triploid endosperm (the nutritive structure surrounding the germ) contain genes transmitted from both the male and female parents. Nonetheless, the genes affecting grain composition and quality are similar enough in most field corn inbreds that crossing any given female with a large variety of male plants does not result in dramatic changes in the compositional or quality characteristics of the resulting seed or grain. Likewise, planting different field corn hybrids within pollinating proximity to each other will not, in most cases, substantially affect the quality of the grain harvested on each type.
In contrast, a minority of commercial corn inbreds or hybrids do contain genes which substantially modify grain quality. These hybrids, include those containing the waxy gene. Such waxy gene hybrids must be isolated from normal, non-waxy corn inbreds or hybrids in order to recover waxy seed or grain. If a non-waxy pollen grain (as found in most field corn inbreds and hybrids) pollinates an ovule borne on a waxy inbred or hybrid, the resulting kernel will be non-waxy, even though adjacent kernels on the same ear, pollinated by waxy pollen, will remain waxy. This immediate effect of pollen genotype on kernel characteristics is termed “xenia”, and the hybrid nature of such kernels is recognizable by particular phenotypic characteristics (color, shape, size, etc.) owing to the direct influence exerted by the genotype of the pollen; Rieger, R., A. Michaelis and M. M. Green, 1968, A Glossary of Genetics and Cytogeneti
Leto Kenneth Joseph
Ulrich James Francis
E. I. du Pont de Nemours and Company
Fox David T.
LandOfFree
Corn plants and products with improved oil composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Corn plants and products with improved oil composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Corn plants and products with improved oil composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3333862