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
1999-12-01
2001-09-04
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
C800S260000, C800S271000, C800S274000, C800S275000, C800S298000, C435S410000, C435S412000, C435S424000, C435S430000
Reexamination Certificate
active
06284954
ABSTRACT:
FIELD OF THE INVENTION
This invention is in the field of maize breeding. Specifically, this invention relates to a novel corn hybrid having the designation P725.
BACKGROUND OF THE INVENTION
Principles of Conventional Plant Breeding
Most 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 seed of an F
1
single cross hybrid. This seed is then sold to commercial grain 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 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 or pollen nonfunctional or by detasseling the plants in the field.
The development of corn hybrids requires the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses. Pedigree breeding, backcross conversion and recurrent selection breeding methods are used to develop the inbred lines from breeding populations. These breeding methods combine desirable traits from two or more inbred lines or various broad-based populations into breeding pools from which new inbred lines are developed by inbreeding or random mating and selection of desired phenotypes. The new inbreds are crossed with other inbreds and the resulting hybrids are evaluated to determine which have commercial value and agronomic usefulness.
The objective of typical plant breeding is to develop a hybrid with desirable traits such as resistance to diseases and insects, herbicide tolerance, tolerance to heat and drought, reduction of time to crop maturity, and improved agronomic quality. Because many crops are harvested mechanically, uniformity of plant characteristics such as germination time, 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 concentration, that cannot readily be obtained in a high-yielding single cross hybrid. One solution to this problem has been proposed by Bergquist et al. in U.S. Pat. Nos. 5,704,160 and 5,706,603, incorporated herein by reference. A primary aspect of this method, known as the TOPCROSS® Grain Production System, is the interplanting of a pollinator corn plant possessing the characteristics for significantly increasing oil level in the resulting grain, with a male sterile hybrid corn plant. The resulting grain possesses an oil concentration much higher than would be expected for self- or cross- pollination of the fertile version of the hybrid corn plant.
In practice, the seed of the pollinator with improved grain quality traits is blended in small amounts with seed of an elite male sterile grain parent hybrid, but with sufficient pollinator seed to permit abundant pollen production for fertilization of the male sterile grain parent hybrid. The relatively low ratio of pollinator seed to male sterile grain parent seed (less than one pollinator plant to every three grain parent plants) takes advantage of the higher grain yield potential of the elite grain parent hybrid while assuring a sufficient population of pollinator plants to pollinate the male sterile grain parent plants.
Critical to the success of the TOPCROSS® Grain Production System is the use of a pollinator capable of enhancing the grain quality traits of the F
1
grain. P725 was developed for this purpose. The present invention, when used as a pollinator, imparts high oil concentration to the resulting F
1
grain without significant loss of yield.
SUMMARY
According to the invention, there is provided a novel corn hybrid, designated P725, that when used to pollinate an elite male sterile hybrid grain parent, produces commercial grain exhibiting improved quality grain traits, including high oil.
P725 is a medium-late flowering hybrid, broadly adapted to the corn growing areas of the Southern and Central United States. P725 has expressed high oil and excellent plant vigor and productivity.
The invention thus relates to the seeds, plants and plant parts of P725; to tissue culture comprising regenerable cells of a plant part of P725; to plants regenerated from regenerable cells of the tissue culture of P725; to corn plants having substantially all the phenotypic, genotypic and/or physiological characteristics of P725; to the method of producing P725; to grain or seed produced by crossing P725 with a different corn plant wherein the resulting progeny have one-half the nuclear genotype of P725; to seed blends of P725 and male sterile corn hybrids; to a method of producing high oil grain using P725 as a pollinator in a TC BLEND® Seed Product; to the parental lines of P725; and to corn plants produced or derived from P725 seed wherein the corn plants have the ability to impart high oil or other grain quality traits to the F
1
grain when these P725-derivatives are used in the TOPCROSS® Grain Production System.
DEFINITIONS
In the description that follows, a number of terms are used. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:
Combining Ability. The ability of a genetic strain, when crossed with another strain, to produce a high proportion of desirable individuals.
Endosperm. The nutritive tissue formed within the embryo sac in seed plants. It commonly arises following the fertilization of the diploid polar nucleus by one male sperm.
Express. To manifest a genetic character trait.
F
1
. The first generation of a cross.
F
2
. The second filial generation obtained by self-fertilization or crossing inter se of F
1
individuals. Subsequent generations are F
3
, F
4
, F
5
, etc.
Genotype. The fundamental genetic constitution of an organism.
Grain. Mature corn kernels produced by commercial growers for purposes other than growing or reproducing the species.
Grain Parent. Male sterile, elite hybrid that comprises a large majority of the plants in the TOPCROSS® Grain Production System.
Grain Quality Trait. Any attribute of grain that is of commercial value. Such traits relate to the intermediate or final use of grain and include but are not limited to the quantity or quality of oil, protein, starch, pigmentation, and fiber found in corn grain. Such traits also encompass physical attributes of the grain itself, such as grain texture, size, or hardness, among others. Certain of these compositional or physical attributes of grain correlate with functional attributes as well which are of commercial importance, such as susceptibility to breakage and spoilage, among others.
Homozygous. A genetic condition existing when identical alleles reside at corresponding loci on homologous chromosomes.
Hybrid. (1) The progeny of a cross fertilization between parents belonging to different genotypes. (2) The first generation offspring of a cross between two individuals differing in one or more genes. (3) A hybrid is the result of a cross between two or more components.
Inbred or Inbred Line. A substantially homozygous individual, variety or line produced by continued inbreeding. In plant breeding a nearly homozygous line usually originates by continued self-fertilization, accompanied by selection.
Kernel. The corn caryopsis comprising a mature embryo and endosperm which are products of double fertilization.
Line. (1) A group of individuals from a common ancestry. (2) A narrowly d
Foley Terry J.
Marshall Lorelei C.
Nubel Douglas S.
Benzion Gary
Bullwinkel Partners Ltd.
Kimball Melissa L.
Optimum Quality Grains, LLC
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