Multicellular living organisms and unmodified parts thereof and – Method of introducing a polynucleotide molecule into or... – The polynucleotide confers pathogen or pest resistance
Reexamination Certificate
1999-07-14
2001-11-13
Bui, Phuong T. (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Method of introducing a polynucleotide molecule into or...
The polynucleotide confers pathogen or pest resistance
C800S295000, C800S287000, C800S278000, C435S069100, C435S320100, C435S252200, C435S468000, C435S419000, C536S023100, C536S023600, C536S024100
Reexamination Certificate
active
06316697
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to disease resistance in plants and more specifically to a plant resistance factor, constitutive disease resistance 1 (CDR1), polynucleotides encoding CDR1, and methods of use thereof for producing transgenic plants having increased pathogen resistance.
BACKGROUND OF THE INVENTION
A plant is considered healthy when it can carry out its physiological functions, such as cell division, differentiation, development, photosynthesis, absorption and translocation of water and nutrients from the soil, metabolism, reproduction, and storage of food supplies, without disruption. When plant functions are disturbed by pathogens, the plants become diseased. Disease can be defined as the malfunctioning of plant host cells and tissues caused by continuous irritation by a pathogenic agent. A disease involves abnormal changes in the form, physiology, or behavior of the plant.
Plant pathogens cause disease by weakening the plant by absorbing food from the plant cells, secreting toxins, enzymes, or growth regulating substances that disturb or kill the plant cells, or block the transport of food nutrients or water in the plant. The roots, stems, leaves, flowers, or fruits can be infected. The affected cells and tissues are weakened or destroyed, and cannot perform normal physiological functions, resulting in reduction of plant growth or death, and reducing crop quality or yield. The major causes of plant diseases are bacteria, mycoplasmas, viruses, nematodes, and fungi. Fugal species from a variety of genera affect plants, including Fusarium, Pythium, Phytophthora, Verticillium, Rhizoctonia, Macrophonmina, Thielaviopsis, Sclerotinia, and numerous others. Plant disease caused by fungi include pre- and post-emergence seedling damping-off, hypocotyl rots, root rots, crown rots, vascular wilt, and other symptoms. Nematodes harmful to plants include nematode species form the genera Meloidogyne, Heterodera, Ditylenchus, and Pratylencus. Plant diseases caused by nematodes include root galls, root rot, lesions, “stubby” root, stunting, and other rots and wilts. Some nematodes (e.g., Trichodorus, Lonoidorus, xipenema) can serve as vectors for virus diseases in a number of plants including Prunus, grape, tobacco, and tomato.
Plant pathogenic bacteria cause a variety of plant disease symptoms. About 80 species of bacteria (e.g.,
Pseudomonas viridiflava, Xanthomonas campestris pv. asclepiadas, Xyellafastidiosa, Acidovorax albilineans
, and
Acidovorax avenae sspl citrulli
) cause disease in plants, including fruit rot, galls, wilts, blight, and leaf spots. As bacteria multiply quickly, controlling them early in the disease process is critical. Copper and streptomycin compounds are the only chemical compounds currently available for the control of bacterial diseases.
The response of plants to microbial attack involves de novo synthesis of an array of proteins designed to restrict the growth of the pathogen. These proteins include hydroxyproline-rich glycoproteins, proteinase inhibitors, enzymes for the synthesis of phyoalexins, enzymes contributing to the reinforcement of cell walls, and certain hydrolytic enzymes.
Plant defenses can also be activated by elicitors derived from microbial cell walls and culture fluids. In dicotyledonous plants, extensive studies have shown that microbial attack or elicitor treatments induces the transcription of a battery of genes encoding proteins involved in the defense response, as part of a massive switch in the overall pattern of gene expression. In contrast, little is known about the inducible defenses in monocotyledonous plants.
Genetic engineering of plants, which entails the isolation and manipulation of genetic material, e.g., DNA or RNA, and the subsequent introduction of that material into a plant or plant cells, has changed plant breeding and agriculture considerably over recent years. Increased crop food values, higher yields, feed value, reduced production costs, pest resistance, stress tolerance, drought resistance, the production of pharmaceuticals, chemicals and biological molecules as well as other beneficial traits are all potentially achievable through genetic engineering techniques. Genetic engineering techniques supplying the genes involved in pathogen resistance have the potential to substantially affect crop production.
SUMMARY OF THE INVENTION
The present invention is based on the discovery of a constitutive disease resistance (CDR1) factor that confers enhanced disease resistance on plants, including resistance to infection by the pathogens
Pseudomonas syringe pv. tomato
(Pst) or
P. syringe pv. maculicola
(Psm, for example).
In one embodiment, substantially purified CDR1 polypeptide is provided. Isolated polynucleotides encoding CDR1 polypeptide, as exemplified by SEQ ID NO:1, are also provided. Vectors containing CDR1, host cells expressing CDR1, and antibodies bind that bind to CDR1 are further provided.
In another embodiment, the invention provides a method of producing a genetically modified plant characterized as having increased disease resistance as compared to a corresponding wild-type plant. The method includes contacting plant cells with nucleic acid encoding an CDR1 polypeptide, operatively associated with an expression control sequence, to obtain transformed plant cells; producing plants from the transformed plant cells; and selecting a plant exhibiting increased disease resistance. A method for genetically modifying a plant cell such that a plant produced from the cell is characterized as having increased disease resistance as compared with a wild-type plant is also provided. The method includes introducing an isolated polynucleotide encoding a CDR1 polypeptide into a plant cell to obtain a transformed plant cell, and growing the transformed plant cell under conditions which permit expression of CDR1 polynucleotide thereby producing a plant having increased disease resistance.
In a further embodiment, a method is provided for producing a genetically modified plant characterized as having increased disease resistance as compared to the corresponding wild type plant by contacting a susceptible plant with a CDR1 promoterinducing amount of an agent necessary to elevate CDR1 gene expression above CDR1 expression in a plant not contacted with the agent. For example, the agent may be a transcription factor or a chemical agent, such as dexamethasone (DEX).
A method is also provided for producing genetically transformed, disease resistant plants, by introducing into the genome of a plant cell, to obtain a transformed plant cell, a nucleic acid sequence having an expression control sequence operably linked to a polynucleotide encoding a CDR1 polypeptide. The invention also provides plants, plant tissue, and seeds produced by plants produced by the methods of the invention.
In yet another embodiment, a method is provided for identifying novel disease resistance genes by probing a nucleic acid libray with at least a fragment of a polynucleotide encoding CDR1, and selecting those clones that hybridize with the fragment.
REFERENCES:
patent: WO 94/16077 (1994-07-01), None
patent: WO 95/02319 (1995-01-01), None
Dixon et al., “Metabolic engineering: prospects for crop improvement through the genetic manipulation of phenylpropanoid biosynthesis and defense responses—a review,”Gene,179:61-71 (1996).
Dixon et al., “Engineering Disease Resistance in Plants: An Overview,”Molecular Methods in Plant Pathology,Sing, Rudra P. et al. (eds). pp. 249-270 (1995).
Dixon Richard A.
Lamb Christopher
Xia Yiji
Bui Phuong T.
Ibrahim Medina A.
Knobbe Martins Olson & Bear LLP
Noble Foundation Inc.
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