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The invention provides methods of modifying the level of expression or functional activity of factors such as enzymes or other catalytic proteins or structural proteins, alone or in concert, to modify the frequency of meiotic homologous recombination involving the exchange of genetic information bet

The invention provides methods of modifying the level of expression or functional activity of factors such as enzymes or other catalytic proteins or structural proteins, alone or in concert, to modify the frequency of meiotic homologous recombination involving the exchange of genetic information between non-sister chromatids from homologous maternal and paternal chromosomes. The steps at which modulation may occur include: homologous chromosome pairing, double-strand break formation; resection; strand invasion; branch migration; and resolution. Methods of plant and animal breeding are also provided that utilize the modulation of meiotic homologous recombination.

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1. A plant cell comprising a heterologous nucleic acid encoding a protein, wherein the protein includes the five conserved motifs of a SPO11 protein and wherein the five conserved motifs further include: arginine at a position corresponding to arginine 99 of SEQ ID NO: 40;tyrosine at a position corr

1. A plant cell comprising a heterologous nucleic acid encoding a protein, wherein the protein includes the five conserved motifs of a SPO11 protein and wherein the five conserved motifs further include: arginine at a position corresponding to arginine 99 of SEQ ID NO: 40;tyrosine at a position corresponding to tyrosine 103 of (SEQ ID NO: 40);arginine at a position corresponding to arginine 130 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 141 of (SEQ ID NO: 40);glutamate at a position corresponding to glutamate 189 of (SEQ ID NO: 40);leucine at a position corresponding to leucine 197 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 215 of (SEQ ID NO: 40);proline at a position corresponding to proline 217 of (SEQ ID NO: 40);threonine at a position corresponding to threonine 221 of (SEQ ID NO: 40);arginine at a position corresponding to arginine 222 of (SEQ ID NO: 40);aspartate at a position corresponding to aspartate 241 of (SEQ ID NO: 40);proline at a position corresponding to proline 244 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 246 of (SEQ ID NO: 40); andisoleucine at a position corresponding to isoleucine 249 of (SEQ ID NO: 40), wherein said nucleic acid is operably linked to a promoter, and wherein expression of the protein in the cell increases the frequency of homologous non-sister chromatid exchange during meiosis. 2. The plant cell of claim 1, wherein the protein has an amino acid sequence that has at least 90% sequence identity to a naturally occurring SPO11 protein obtained from the plant species in which the frequency of homologous non-sister chromatid exchange during meiosis is increased, the sequence identity being calculated when the amino acid sequences are optimally aligned. 3. A plant cell comprising a nucleic acid encoding a protein, wherein the protein includes the five conserved motifs of a SPO 11 protein and wherein the five conserved motifs further include: arginine at a position corresponding to arginine 99 of SEQ ID NO: 40;arginine at a position corresponding to arginine 130 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 141 of (SEQ ID NO: 40);glutamate at a position corresponding to glutamate 189 of (SEQ ID NO: 40);leucine at a position corresponding to leucine 197 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 215 of (SEQ ID NO: 40);proline at a position corresponding to proline 217 of (SEQ ID NO: 40);threonine at a position corresponding to threonine 221 of (SEQ ID NO: 40);arginine at a position corresponding to arginine 222 of (SEQ ID NO: 40);aspartate at a position corresponding to aspartate 241 of (SEQ ID NO: 40);proline at a position corresponding to proline 244 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 246 of (SEQ ID NO: 40); andisoleucine at a position corresponding to isoleucine 249 of (SEQ ID NO: 40), wherein the protein lacks a tyrosine at a position corresponding to tyrosine 103 of SEQ ID NO: 40, wherein the protein has an ability to inhibit double strand break catalysis by an endogenous SPO11 protein, and wherein said nucleic acid is operably linked to a promoter, and wherein expression of the protein alters the activity of the endogenous SPO11 protein to decrease the frequency of homologous non-sister chromatid exchange during meiosis. 4. The plant cell of claim 3, wherein the protein has an amino acid sequence that has at least 90% sequence identity to a naturally occurring SPO11 protein obtained from the plant species in which the frequency of homologous non-sister chromatid exchange during meiosis is decreased, the sequence identity being calculated when the amino acid sequences are optimally aligned. 5. A method of increasing meiotic homologous recombination in a cell of a plant species comprising: transforming a progenitor of the cell with a nucleic acid encoding a protein, wherein the protein includes the five conserved motifs of a SPO11 protein and wherein the five conserved motifs further include: arginine at a position corresponding to arginine 99 of Arabidopsis thaliana (AtSpo11) (SEQ ID NO: 40);tyrosine at a position corresponding to tyrosine 103 of (SEQ ID NO: 40);arginine at a position corresponding to arginine 130 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 141 of (SEQ ID NO: 40);glutamate at a position corresponding to glutamate 189 of (SEQ ID NO: 40);leucine at a position corresponding to leucine 197 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 215 of (SEQ ID NO: 40);proline at a position corresponding to proline 217 of (SEQ ID NO: 40);threonine at a position corresponding to threonine 221 of (SEQ ID NO: 40);arginine at a position corresponding to arginine 222 of (SEQ ID NO: 40);aspartate at a position corresponding to aspartate 241 of (SEQ ID NO: 40);proline at a position corresponding to proline 244 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 246 of (SEQ ID NO: 40); andisoleucine at a position corresponding to isoleucine 249 of (SEQ ID NO: 40),wherein the protein is operable to initiate meiotic recombination, wherein said nucleic acid is operably linked to a promoter; andallowing the transformed cell, or a descendant of the transformed cell, to undergo meiosis to produce a viable gamete, wherein expression of the protein in the cell undergoing meiosis increases the frequency of homologous non-sister chromatid exchange during the meiosis. 6. The method of claim 1, wherein the protein has an amino acid sequence that has at least 90% sequence identity to a naturally occurring SPO11 protein obtained from the plant species in which the meiotic homologous recombination is increased, the sequence identity being calculated when the amino acid sequences are optimally aligned. 7. A method of decreasing meiotic homologous recombination in a cell of a plant species comprising: transforming the cell with a nucleic acid encoding a mutant protein, wherein the protein includes the five conserved motifs of a SPO11 protein and wherein the five conserved motifs further include: arginine at a position corresponding to arginine 99 of SEQ ID NO: 40;arginine at a position corresponding to arginine 130 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 141 of (SEQ ID NO: 40);glutamate at a position corresponding to glutamate 189 of (SEQ ID NO: 40);leucine at a position corresponding to leucine 197 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 215 of (SEQ ID NO: 40);proline at a position corresponding to proline 217 of (SEQ ID NO: 40);threonine at a position corresponding to threonine 221 of (SEQ ID NO: 40);arginine at a position corresponding to arginine 222 of (SEQ ID NO: 40);aspartate at a position corresponding to aspartate 241 of (SEQ ID NO: 40);proline at a position corresponding to proline 244 of (SEQ ID NO: 40);glycine at a position corresponding to glycine 246 of (SEQ ID NO: 40); andisoleucine at a position corresponding to isoleucine 249 of (SEQ ID NO: 40),wherein the mutant protein lacks a tyrosine at a position corresponding to tyrosine 103 of SEQ ID NO: 40 wherein the mutant protein has an ability to inhibit double strand break catalysis by an endogenous SPO11 protein, and wherein said nucleic acid is operably linked to a promoter; andallowing the transformed plant cell, or a descendent of the transformed plant cell to undergo meiosis to produce a viable gamete, wherein expression of the mutant SPO11 protein in the cell undergoing meiosis alters the activity of the endogenous SPO11 protein to decrease the frequency of homologous non-sister chromatid exchange. 8. The method of claim 7, wherein the protein has an amino acid sequence that has at least 90% sequence identity to a naturally occurring SPO11 protein obtained from the plant species in which the frequency of homologous non-sister chromatid exchange during meiosis is decreased, the sequence identity being calculated when the amino acid sequences are optimally aligned. 9. The method of claim 7, wherein the protein comprises a phenylalanine at the position corresponding to tyrosine 103 of SEQ ID NO: 40. 10. The method of claim 1 or claim 7, wherein the promoter is inducible or repressible, wherein induction of the promoter increases expression of the nucleic acid, or wherein repression of the promoter inhibits expression of the nucleic acid. 11. The method of claim 1 or claim 7, wherein the viable gamete is crossed with a second gamete to obtain a progeny cell. 12. The method of claim 1 or claim 7, wherein the level of expression of the protein is regulatable to increase or decrease the level of meiotic homologous recombination. 13. The method of claim 1 or claim 7, wherein the promoter is active during meiosis.