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
2001-12-19
2003-11-11
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
C800S271000, C800S275000, C800S278000, C800S279000, C800S281000, C800S284000, C800S288000, C800S300100, C800S302000, C435S412000, C435S421000, C435S430000, C435S430100
Reexamination Certificate
active
06646188
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to maize improvement. More specifically, this invention relates to an inbred maize line designated PSA104.
BACKGROUND OF THE INVENTION
Maize
Maize or corn (
Zeays mays
L.) is a major annual crop species grown for grain and forage. A monocot, maize is a member of the grass family (Gramineae) and bears seeds in female inflorescences (usually called ears) and pollen in separate male inflorescences (usually called tassels).
In the U.S., maize is almost exclusively produced by growing hybrid varieties (cultivars). Maize hybrids are typically produced by seed companies and sold to farmners. On farms, maize hybrids are usually grown as a row crop. During the growing season herbicides are widely used to control weeds; fertilizers are used to maximize yields; and fungicides and insecticides are often used to control disease pathogens and insect pests. Before maturity, maize plants may be chopped and placed in storage where the chopped forage (stover) undergoes fermentation to become silage for livestock feed. At maturity in the fall, the seeds are harvested as grain. The grain may be directly fed to livestock or transported to storage facilities. From storage facilities, the grain is transported to be used in making an extremely large number of products, including food ingredients, snacks, pharmaceuticals, sweeteners, and paper products (see, e.g., S. A. Watson and P. E. Ramstad, Eds., Corn: Chemistry and Technology, American Association of Cereal Chemists, Inc., St. Paul, Minn. (1987)).
While the agronomic performance of maize hybrids has improved, there is a continuing need to develop better hybrids with increased and more dependable grain and stover yields. Moreover, heat and drought stress and continually changing insect predators and disease pathogens present hazards to farmers as they grow maize hybrids. Thus, there is a continual need for maize hybrids which offer higher grain yields in the presence of heat, drought, pathogens and insects.
Inbred Lines and Hybrid Varieties
The ultimate purpose for developing maize inbred lines is to be able to dependably produce hybrids. Commercially viable maize hybrids, like hybrids in many other crop species, manifest heterosis or hybrid vigor for most economically important traits.
Plants resulting from self-pollination (or from other forms of inbreeding) for several generations are termed inbreds (inbred lines). These inbreds are homozygous at almost all loci. When self-pollinated, these inbreds produce a genetically uniform population of true breeding inbred progeny. These inbred progeny possess genotypes and phenotypes essentially identical to that of their inbred parent. A cross between two different inbreds produces a genetically uniform population of hybrid F
1
plants. These F
1
plants are genetically uniform, but are highly heterozygous. Progeny from a cross between two hybrid F
1
plants are also highly heterozygous, but are not genetically uniform.
One important result of this phenomenon is that seed supplies of an inbred may be increased by self-pollinating the inbred plants. Equivalently, seed supplies of the inbred may be increased by growing inbred plants such that only pollen from these inbred plants is present during flowering (anthesis), e.g., in spaced or timed isolation. Seed arising from inbred parents successfully grown in isolation is genetically identical to the inbred parents. Another important result is that hybrids of inbred lines always have the same appearance and uniformity and can be produced by crossing the same set of inbreds whenever desired. This is because inbreds, themselves, are genetically uniform. Thus, a hybrid created by crossing a defined set of inbreds will always be the same. Moreover, once the inbreds giving rise to a superior hybrid are identified, a continual supply of the hybrid seed can be produced by crossing these identified inbred parents.
Types of hybrids include single-cross, three-way, and double-cross. Single-cross hybrids are the F
1
progeny of a cross between two inbred lines (inbreds), e.g., A×B, in which A and B are inbreds. Three-way hybrids are the first generation progeny of a cross between a single-cross hybrid and an inbred, e.g., (A×B)×C, in which A×B is a single-cross hybrid of inbreds A and B and C is another inbred. Double-cross hybrids are the first generation progeny of a cross between two single-cross hybrids, e.g., (A×B)×(C×D), in which A×B and C×D are single-cross hybrids of inbreds A and B and C and D, respectively. In the U.S., single-cross hybrids currently occupy the largest proportion of the acreage used in maize production. As will be shown below, maize inbreds are assemblages of true breeding, homozygous, substantially identical (homogeneous) individuals. Single-cross hybrids are both homogeneous and highly heterozygous and are not true breeding. Three-way and double-cross hybrids are less homogeneous, but are nonetheless highly heterozygous and not true breeding as well. Hence, the only way of improving hybrids is improving component inbreds thereof. Improving maize inbreds involves procedures and concepts developed from the discipline of plant breeding.
Plant Breeding
Developing improved maize hybrids requires the development of improved maize inbreds. Maize breeding programs typically combine the genetic backgrounds from two or more inbred lines or various other broad based germplasm sources into breeding populations from which new inbred lines are developed by self-pollination (or other forms of inbreeding) and selection for desired phenotypes. The newly developed inbreds are crossed to other inbred tester lines and the hybrids from these tester crosses are then evaluated to determine whether these hybrids might have commercial potential. Thus, the invention of a new maize variety requires a number of steps. As a nonlimiting illustration, these steps may include:
(1) selecting plants for initial crosses;
(2) crossing the selected plants in a mating scheme to generate F
1
progeny;
(3) self-pollinating the F
1
progeny to generate segregating F
2
progeny;
(4) sequentially self-pollinating and selecting progeny from the F
2
plants for several generations to produce a series of newly developed inbreds, which breed true and are highly uniform, yet which differ from each other;
(5) crossing the newly developed inbred lines with other unrelated inbred lines (testers) to produce hybrid seed; and
(6) evaluating the tester hybrids in replicated and unreplicated performance trials to determine their commercial value.
Plants are selected from germplasm pools to improve hybrid traits such as grain and stover yield, resistance or tolerance to diseases, insects, heat and drought, stalk quality, ear retention, and end use qualities. The plants from the germplasm pools are then crossed to produce F
1
plants and the F
1
plants are self-pollinated to generate populations of F
2
plants. Self-pollination and selection in F
2
plants and subsequent generations are illustrated below in a nonlimiting example of a pedigree method of breeding.
In the nursery, F
2
plants are self-pollinated and selected for stalk quality, reaction to diseases and insects, and other traits, which are visually scored. During the next growing season, seeds from each selected self-pollinated F
2
plant are planted in a row and grown as F
2
-derived, F
3
families. Selection and self-pollination is practiced among and within these F
3
families. In a subsequent growing season, seeds from each selected F
3
plant are planted in a row and grown as F
3
-derived, F
4
families. Selection and self-pollination are again practiced among and within these F
4
families. In a subsequent growing season, seeds from each selected F
4
plant are planted in a row and grown as F
4
-derived, F
5
families. At this point, selection is practiced predominantly among families, rather than within families, because plants within families tend to be uniform and are approaching homozygosity and homogeneity. Seeds from sel
Euralis USA S.A.
Fox David T.
Patterson Thuente Skaar & Christensen P.A.
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