BACKGROUND

There are numerous steps in the development of any novel, desirable maize variety. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germ plasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The breeder's goal is to combine in a single variety or hybrid, various desirable traits. For field crops, these traits may include resistance to diseases and insects, resistance to heat and drought, reducing the time to crop maturity, greater yield, altered fatty acid profile, abiotic stress tolerance, improvements in compositional traits, and better agronomic characteristics and quality.

These product development processes, which lead to the final step of marketing and distribution, can take from six to twelve years from the time the first cross is made until the finished seed is delivered to the farmer for planting. Therefore, development of new varieties and hybrids is a time-consuming process. A continuing goal of maize breeders is to develop stable, high yielding maize varieties and hybrids that are agronomically sound with maximal yield over one or more different conditions and environments.

SUMMARY

Provided is a novel maize,Zea maysL., variety, designated PH48Y7 and processes for making PH48Y7. Seed of maize variety PH48Y7, plants of maize variety PH48Y7, plant parts and cells of maize variety PH48Y7, and to processes for making a maize plant that comprise crossing maize variety PH48Y7 with another maize plant are provided. Also provided are maize plants having all the physiological and morphological characteristics of the inbred maize variety PH48Y7.

Processes are provided for making a maize plant containing in its genetic material one or more traits introgressed into PH48Y7 through one or more of backcross conversion, genetic manipulation and transformation, and to the maize seed, plant and plant parts produced thereby. Hybrid maize seed, plants or plant parts produced by crossing the variety PH48Y7 or a locus conversion of PH48Y7 with another maize variety are also provided.

The inbred maize plant may further comprise a cytoplasmic or nuclear factor capable of conferring male sterility or otherwise preventing self-pollination, such as by self-incompatibility. Parts of the maize plant described herein are also provided, for example, pollen obtained from an inbred plant and an ovule of the inbred plant.

Seed of the inbred maize variety PH48Y7 is provided. The inbred maize seed may be an essentially homogeneous population of inbred maize seed of the variety designated PH48Y7. Essentially homogeneous populations of inbred seed are generally free from substantial numbers of other seed. Therefore, inbred seed generally forms at least about 97% of the total seed. The population of inbred maize seed may be particularly defined as being essentially free from hybrid seed. The inbred seed population may be separately grown to provide an essentially homogeneous population of inbred maize plants designated PH48Y7.

Compositions are provided comprising a seed of maize variety PH48Y7 comprised in plant seed growth media. In certain embodiments, the plant seed growth media is a soil or synthetic cultivation medium. In specific embodiments, the growth medium may be comprised in a container or may, for example, be soil in a field.

Maize variety PH48Y7 comprising an added heritable trait is provided. The heritable trait may comprise a genetic locus that is a dominant or recessive allele. In certain embodiments, a plant of maize variety PH48Y7 comprising a single locus conversion is provided. The locus conversion may be one which confers one or more traits such as, for example, male sterility, herbicide tolerance, insect resistance, disease resistance (including, for example) bacterial, fungal, nematode or viral disease, waxy starch, modified fatty acid metabolism, modified phytic acid metabolism, modified carbohydrate metabolism and modified protein metabolism is provided. The trait may be, for example, conferred by a naturally occurring maize gene introduced into the genome of the variety by backcrossing, a natural or induced mutation, or a transgene introduced through genetic transformation techniques. When introduced through transformation, a genetic locus may comprise one or more transgenes integrated at a single chromosomal location.

An inbred maize plant of the variety designated PH48Y7 is provided, wherein a cytoplasmically-inherited trait has been introduced into the inbred plant. Such cytoplasmically-inherited traits are passed to progeny through the female parent in a particular cross. An exemplary cytoplasmically-inherited trait is the male sterility trait. Cytoplasmic-male sterility (CMS) is a pollen abortion phenomenon determined by the interaction between the genes in the cytoplasm and the nucleus. Alteration in the mitochondrial genome and the lack of restorer genes in the nucleus will lead to pollen abortion. With either a normal cytoplasm or the presence of restorer gene(s) in the nucleus, the plant will produce pollen normally. A CMS plant can be pollinated by a maintainer version of the same variety, which has a normal cytoplasm but lacks the restorer gene(s) in the nucleus, and continues to be male sterile in the next generation. The male fertility of a CMS plant can be restored by a restorer version of the same variety, which has the restorer gene(s) in the nucleus. With the restorer gene(s) in the nucleus, the offspring of the male-sterile plant can produce normal pollen grains and propagate. A cytoplasmically inherited trait may be a naturally occurring maize trait or a trait introduced through genetic transformation techniques.

A tissue culture of regenerable cells of a plant of variety PH48Y7 is provided. The tissue culture can be capable of regenerating plants capable of expressing all of the physiological and morphological or phenotypic characteristics of the variety, and of regenerating plants having substantially the same genotype as other plants of the variety. Examples of some of the physiological and morphological characteristics that may be assessed include characteristics related to yield, maturity, and kernel quality. The regenerable cells in such tissue cultures can be derived, for example, from embryos, meristematic cells, immature tassels, microspores, pollen, leaves, anthers, roots, root tips, silk, flowers, kernels, ears, cobs, husks, or stalks, or from callus or protoplasts derived from those tissues. Maize plants regenerated from the tissue cultures, and plants having all the physiological and morphological characteristics of variety PH48Y7 are also provided.

Processes are provided for producing maize seeds or plants, which processes generally comprise crossing a first parent maize plant as a male or female parent with a second parent maize plant, wherein at least one of the first or second parent maize plants is a plant of the variety designated PH48Y7. These processes may be further exemplified as processes for preparing hybrid maize seed or plants, wherein a first inbred maize plant is crossed with a second maize plant of a different, distinct variety to provide a hybrid that has, as one of its parents, the inbred maize plant variety PH48Y7. In these processes, crossing will result in the production of seed. The seed production occurs regardless of whether the seed is collected or not.

In some embodiments, the first step in “crossing” comprises planting, such as in pollinating proximity, seeds of a first and second parent maize plant, and preferably, seeds of a first inbred maize plant and a second, distinct inbred maize plant. Where the plants are not in pollinating proximity, pollination can be acheived by transferring a pollen or tassel bag from one plant to the other as described below.

A second step comprises cultivating or growing the seeds of said first and second parent maize plants into plants that bear flowers—male flowers (tassels) and female flowers (silks).

A third step comprises preventing self-pollination of the plants, i.e., preventing the silks of a plant from being fertilized by any plant of the same variety, including the same plant. This can be done by emasculating the male flowers of the first or second parent maize plant, (i.e., treating or manipulating the tassels so as to prevent pollen production, to produce an emasculated parent maize plant). Self-incompatibility systems may also be used in some hybrid crops for the same purpose. Self-incompatible plants still shed viable pollen and can pollinate plants of other varieties but are incapable of pollinating themselves or other plants of the same variety.

A fourth step may comprise allowing cross-pollination to occur between the first and second parent maize plants. When the plants are not in pollinating proximity, this is done by placing a bag, usually paper or glassine, over the tassels of the first plant and another bag over the silks of the incipient ear on the second plant. The bags are left in place for at least 24 hours. Since pollen is viable for less than 24 hours, this assures that the silks are not pollinated from other pollen sources, that any stray pollen on the tassels of the first plant is dead, and that the only pollen transferred comes from the first plant. The pollen bag over the tassel of the first plant is then shaken vigorously to enhance release of pollen from the tassels, and the shoot bag is removed from the silks of the incipient ear on the second plant. Finally, the pollen bag is removed from the tassel of the first plant and is placed over the silks of the incipient ear of the second plant, shaken again and left in place. Yet another step comprises harvesting the seeds from at least one of the parent maize plants. The harvested seed can be grown to produce a maize plant or hybrid maize plant.

Also provided are maize seed and plants produced by a process that comprises crossing a first parent maize plant with a second parent maize plant, wherein at least one of the first or second parent maize plants is a plant of the variety designated PH48Y7. In one embodiment, maize seed and plants produced by the process are first generation (F1) hybrid maize seed and plants produced by crossing an inbred with another, distinct plant such as another inbred. Seed of an F1 hybrid maize plant and an F1 hybrid maize plant and seed thereof are provided.

The genetic complement of the maize plant variety designated PH48Y7 is provided. The phrase “genetic complement” is used to refer to the aggregate of nucleotide sequences, the expression of which sequences defines the phenotype of, in the present case, a maize plant, or a cell or tissue of that plant. A genetic complement thus represents the genetic make-up of an inbred cell, tissue or plant, and a hybrid genetic complement represents the genetic make-up of a hybrid cell, tissue or plant. Maize plant cells that have a genetic complement in accordance with the inbred maize plant cells disclosed herein, and plants, seeds and diploid plants containing such cells are provided.

Plant genetic complements may be assessed by genetic marker profiles, and by the expression of phenotypic traits that are characteristic of the expression of the genetic complement, e.g., isozyme typing profiles. It is understood that variety PH48Y7 could be identified by any of the many well-known techniques used for genetic profiling disclosed herein.

In another aspect, hybrid genetic complements are provided, as represented by maize plant cells, tissues, plants, and seeds, formed by the combination of a haploid genetic complement of an inbred maize plant disclosed herein with a haploid genetic complement of a second maize plant, such as, another, distinct inbred maize plant. In another aspect, a maize plant regenerated from a tissue culture that comprises a hybrid genetic complement of the inbred maize plant disclosed herein.

Methods of producing an inbred maize plant derived from the maize variety PH48Y7 are provided, the method comprising the steps of: (a) preparing a progeny plant derived from maize variety PH48Y7, wherein said preparing comprises crossing a plant of the maize variety PH48Y7 with a second maize plant; (b) crossing the progeny plant with itself or a second plant to produce a seed of a progeny plant of a subsequent generation; (c) repeating steps (a) and (b) with sufficient inbreeding until a seed of an inbred maize plant derived from the variety PH48Y7 is produced. In the method, it may be desirable to select particular plants resulting from step (c) for continued crossing according to steps (b) and (c). By selecting plants having one or more desirable traits, an inbred maize plant derived from the maize variety PH48Y7 is obtained which possesses some of the desirable traits of maize variety PH48Y7 as well as potentially other selected traits.

