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
1999-06-08
2001-05-29
Benzion, Gary (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
C800S298000, C800S275000, C800S271000, C800S268000, C800S266000, C800S264000, C435S412000, C435S424000, C435S430000, C435S430100
Reexamination Certificate
active
06239335
ABSTRACT:
FIELD OF THE INVENTION
This invention is in the field of plant breeding. Specifically, this invention relates to a novel synthetic corn hybrid having the designation P89 and useful in the proprietary TOPCROSS® grain production system described in U.S. Pat. Nos. 5,704,160 and 5,706,603 by Bergquist et al.
BACKGROUND OF THE INVENTION
Uses of Corn
Corn (
Zea mays L
.) is an important crop used as a human food source, animal feed, and as a raw material in industry. The food uses of corn, in addition to the human consumption of corn kernels, include products of both the dry milling and wet milling industries. The principal products of dry milling include grits, meal and flour. The principal products of wet milling include starch, syrups, and dextrose. A by-product of both dry and wet milling is corn oil, which is recovered from corn germ. As animal feed, corn is used primarily as a feedstock for beef cattle, dairy cattle, swine, poultry, and fish.
Industrial uses of corn mainly consist of the use of corn starch produced by wet milling and corn flour produced by dry milling and the whole kernel fermentation for production of foodgrade and industrial use ethanol. The industrial applications of corn starch and flour are based on their functional properties, such as viscosity, film formation ability, adhesiveness, absorbent properties and ability to suspend particles. Corn starch and flour are used in the paper and textile industries, and as components in adhesives, building materials, foundry binders, laundry starches, sanitary diapers, seed treatments, explosives, and oil-well muds. Plant parts other than the corn kernels are also used in industry. For example, stalks and husks can be made into paper and wallboard, and corn cobs can be used for fuel and to make charcoal.
Principles of Conventional Plant Breeding
The majority of the commercial corn produced in the United States is produced from hybrid seed. The production of hybrid seed first requires the development of elite corn inbred lines that possess good combining ability to produce agronomically superior hybrids. The majority of hybrid seed produced in the United States is of the single cross type, wherein two inbred lines are intermated, or crossed, to produce what is termed an F
1
single cross hybrid. The resulting kernels from this intermating are then sold as seed to commercial growers who plant the seed and harvest the second generation, or F
2
grain, for use on farm or for commercial sale.
The production of a conventional single cross hybrid seed involves controlling the direction of pollination from one inbred to the other to assure the production of predominantly hybrid (cross pollinated) seed. Typically, directed pollination is accomplished by interplanting separate rows of female corn plants with male corn plants. The female corn plants that are male sterile may be produced by genetic mechanisms which render the corn tassel nonfunctional or by detasseling the plants in the field.
The development of corn hybrids requires the development of homozygous inbred lines or uniform synthetic populations of unique heterotic background, the crossing of these lines or synthetic populations, and evaluation of test crosses. Pedigree breeding and recurrent selection breeding programs are used to develop inbred lines and synthetic populations from breeding populations. Breeding programs combine desirable traits from two or more inbred lines or various broad-based sources into breeding pools from which new inbred lines or synthetic populations are developed by inbreeding or random mating and selection of desired phenotypes. The new inbreds and/or synthetic lines are crossed with other inbred lines and/or synthetic populations and the hybrids from these crosses are evaluated to determine which have commercial value and agronomic usefulness.
Pedigree breeding starts with the crossing of two genotypes, each of which may have one or more desirable characteristics that is lacking in the other or which complements the other. If the two original genotypes do not provide all of the desired characteristics, other sources can be included during the breeding. In the pedigree breeding method, superior plants are selfed or random mated and the resulting seed selected in successive generations. Pedigree records of ancestry are carefully maintained for each family and ear row selection through succeeding generations. In the succeeding generations, the heterozygous condition of the corn germplasm gives way to homozygous true breeding lines as a result of inbreeding and selection. Typically, in the pedigree method of breeding, five or more generations of inbreeding and selection is practiced.
Backcrossing can be used to improve an inbred line by transferring a specific desirable trait from one inbred or source to another inbred that lacks that trait. This can be accomplished, for example, by first crossing a superior inbred (recurrent parent) to a donor inbred (nonrecurrent parent). The donor inbred carries (donates) the appropriate gene(s) for the desired trait to the next generation. After five or more backcross generations with selection for the desired trait, the inbred will be heterozygous for loci controlling the characteristic being transferred, but will be like the superior parent for most or almost all other genes. The last backcross generation can be selfed to produce a pure breeding progeny for the gene(s) being transferred.
An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between any two inbreds will always be the same. Once the inbreds or synthetics that give the best hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred or synthetic parents is maintained.
As previously noted, a single cross hybrid is produced when two unrelated inbred or synthetic lines are crossed to produce the F
1
progeny. A three-way cross hybrid is produced from three inbred lines (or synthetics) where two of the inbred lines (or synthetics) are crossed (A×B) and then the resulting F
1
hybrid is crossed with the third inbred (or synthetics) (A×B)XC. A double cross hybrid is produced from four inbred lines (or synthetics) by crossing pairs (A×B) and (C×D) and then crossing the two F
1
hybrids (A×B)×(C×D).
Much of the hybrid vigor exhibited by F
1
hybrids is lost in the next generation (F
2
). Consequently, seed (grain) from hybrid varieties is not used for planting stock.
The objective of typical plant breeding is to combine in a single variety/hybrid the desirable traits of the parental lines. For field crops such as corn, these desirable traits may include resistance to diseases, insects, herbicide tolerance, and tolerance to heat and drought, reducing time to crop maturity, and improved agronomic quality. With mechanical harvesting of many crops, uniformity of plant characteristics such as germination time and stand establishment, growth rate, and fruit/seed size are also desirable.
The problem with conventional breeding techniques is that there are several grain quality traits, such as high oil content, that cannot readily be combined in a high-yielding single cross hybrid. By contrast, synthetic hybrids, such as the one described herein, when used as a pollinator in the TOPCROSS® grain production system, can impart desirable grain quality characteristics, such as high oil content, to the resulting F
1
grain without a significant loss in yield.
Synthetic Varieties
A synthetic hybrid consists of an array of similar genotypes that were identified from intercross tests and bulked into a random mating population having a desired phenotype. The intercrosses between two different heterotic groups results in the continuous production of a specific synthetic hybrid of desired phenotype.
Corn has male flowers, located on the tassel, and female flowers, located on the ear, of the same plant. Because of this monoecy, corn plants can be bred by both self-pollination and cross-pollination techniques. Corn is self-
Benzion Gary
Bullwinkel Partners Ltd.
Optimum Quality Grains, L.L.C.
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