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
1993-03-05
2002-04-16
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
C800S274000, C800S278000, C800S279000, C800S286000, C800S287000, C800S288000, C800S300000, C800S302000, C435S069100, C435S069800, C435S198000, C435S199000, C435S209000, C435S219000, C435S320100, C435S419000, C536S023400, C536S023600, C536S023720
Reexamination Certificate
active
06372967
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a male-sterile plant and to its reproduction material (e.g., seeds), in which the cells are transformed so that a foreign DNA sequence is stably integrated into their nuclear genome. The foreign DNA sequence of this invention contains at least one first foreign DNA (hereinafter the “male-sterility DNA”) that: 1) encodes a first RNA or protein or polypeptide which, when produced or overproduced in a stamen cell of the plant, disturbs significantly the metabolism, functioning and/or development of the stamen cell; and 2) is in the same transcriptional unit as, and under the control of, a first promoter which is capable of directing expression of the male-sterility DNA selectively in stamen cells of the plant. In particular, this invention relates to such a nuclear male-sterile plant and its reproduction material, in which the foreign DNA sequence of this invention is a foreign chimaeric DNA sequence that can also contain at least one second foreign DNA (the “marker DNA”) that: 1) encodes a second RNA or protein or polypeptide which, when present at least in a specific tissue or specific cells of the plant, renders the entire plant easily separable from other plants that do not contain the second RNA, protein or polypeptide at least in the specific tissue or specific cells; 2) is in the same transcriptional unit as, and under the control of, a second promoter which is capable of directing expression of the marker DNA in at least the specific tissue or the specific cells of the plant; and 3) is in the same genetic locus of the nuclear genome of the cells of the plant as the male-sterility DNA.
This invention also relates to a foreign chimaeric DNA sequence that contains at least one male-sterility DNA under the control of the first promoter and that can also contain, adjacent to the male-sterility DNA, at least one marker DNA under the control of the second promoter.
This invention further relates to a vector that contains the foreign DNA sequence of this invention and is suitable for the transformation of plant cells, whereby the foreign DNA sequence is stably integrated into the nuclear genome of the cells.
This invention still further relates to cells of a plant and to plant cell cultures, the nuclear genomes of which are transformed with the foreign DNA sequence.
This invention yet further relates to a process for producing a nuclear male-sterile plant and its reproduction material and its cell cultures containing the foreign DNA sequence in which the male-sterility DNA: 1) is under the control of the first promoter and optionally in the same genetic locus as the marker DNA under the control of the second promoter; 2) is stably integrated into the nuclear genome of the plant's cells; and 3) can be expressed selectively in stamen cells of the plant in the form of the first RNA, protein or polypeptide.
The invention further relates to a process for producing hybrid seeds, which grow into hybrid plants, by crossing: 1) the male-sterile plant of this invention which includes, in its nuclear genome, the marker DNA, preferably encoding a protein conferring a resistance to a herbicide on the plant; and 2) a male-fertile plant without the marker DNA in its genome. This invention particularly relates to such a process for producing hybrid seeds on a commercial scale, preferably in a substantially random population, without the need for extensive hand-labor.
This invention still further relates to a tapetum-specific promoter from a plant genome. This promoter can be used as the first promoter in the foreign DNA sequence of this invention for transforming the plant to render it nuclear male-sterile.
BACKGROUND OF THE INVENTION
Hybridization of plants is recognized as an important process for producing offspring having a combination of the desirable traits of the parent plants. The resulting hybrid offspring often have the ability to outperform the parents in different traits, such as in yield, adaptability to environmental changes, and disease resistance. This ability is called “heterosis” or “hybrid vigor”. As a result, hybridization has been used extensively for improving major crops, such as corn, sugarbeet and sunflower. For a number of reasons, primarily related to the fact that most plants are capable of undergoing both self-pollination and cross-pollination, the controlled cross-pollination of plants without significant self-pollination, to produce a harvest of hybrid seeds, has been difficult to achieve on a commercial scale.
In nature, the vast majority of crop plants produce male and female reproductive organs on the same plant, usually in close proximity to one another in the same flower. This favors self-pollination. Some plants, however, are exceptions as a result of the particular morphology of their reproductive organs which favors cross-pollination. These plants produce hybrid offspring with improved vigor and adaptability. One such morphology in Cannabis ssp. (hemp) involves male and female reproduction organs on separate plants. Another such morphology in
Zea mays
(corn) involves male and female reproductive organs on different parts of the same plant. Another such morphology in
Elaeis quineensis
(oilpalm) involves male and fertile female gametes which become fertile at different times in the plant's development.
Some other plant species, such as
Ananas comosus
(pineapple), favor cross-pollination through the particular physiology of their reproductive organs. Such plants have developed a so-called “self-incompatibility system” whereby the pollen of one plant is not able to fertilize the female gamete of the same plant or of another plant with the same genotype.
Some other plant species favor cross-pollination by naturally displaying the so-called genomic characteristic of “male sterility”. By this characteristic, the plants' anthers degenerate before pollen, produced by the anthers, reach maturity. See: “Male-Sterility in Higher Plants”, M. L. H. Kaul, 1987, in: Monographs on Theoretical and Applied Genetics 10, Edit. Springer Verlag. Such a natural male-sterility characteristic is believed to result from a wide range of natural mutations, most often involving recessive deficiencies, and this characteristic can not easily be maintained in plant species that predominantly self-pollinate, since under natural conditions, no seeds will be produced.
There are four main types of male sterility observed in nature. All four types of male sterility are used in commercial breeding programs to ensure that there is cross-pollination to produce hybrid seed for crops such as corn, sugarbeet, oilseed rape and sunflower.
One type of male sterility is nuclear encoded and is believed to be inherited as a recessive allele. For breeding purposes, a recessive male-sterile parent plant is maintained by crossing it with a heterozygous male-fertile plant that also includes the recessive male-sterility allele, so that the offspring are 50% recessive male-sterile plants. The other 50% are male-fertile plants that have to be rogued out in outcrossing programs which can only be done efficiently if the recessive male-sterility allele is segregated together with a selectable or screenable marker. In U.S. Pat. No. 4,727,219, a procedure is described for the use of recessive male sterility for the production of hybrid maize.
A second type of male sterility is nuclear encoded but inherited as a dominant allele. An advantage of dominant male sterile plants, as compared to recessive male sterile plants, is that the dominant male-sterile plants can be maintained through crossing with a male-fertile plant, to produce offspring that are 50% dominant male-sterile plants. The usefulness of this dominant nuclear male-sterile plant is, however, limited because its dominant male-sterility allele is in most cases not tightly linked (i.e., within the same genetic locus) to a selectable or screenable marker.
A third type of male sterility is cytoplasmatically encoded. In most cases, the cytoplasmic code is in the mitochondrial genome of the pla
De Beuckeleer Marc
De Greef Willy
Leemans Jan
Mariani Celestina
Aventis CropScience N.V.
Burns Doane Swecker & Mathis L.L.P.
Fox David T.
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