Creation and transmission of megaloci

Abstract

The current invention provides methods for creating a block of genetically linked transgenic traits or a megalocus that can be transmitted as a single genetic unit. The present invention further provides methods for trait introgression to other plants, varieties or species using the megaloci of the invention. Also provided are plants, seeds, and plant parts comprising the megaloci.

What is claimed is: 
     
         1 . A method for producing a megalocus on a plant chromosome comprising:
 (a) obtaining a hybrid plant comprising a first locus and a second locus, where the first locus is transgenic and the second locus comprises an endogenous trait locus or is transgenic, where the first and second loci are located on different homologous chromosomes, and where the loci are at genetically linked positions in said homologous chromosomes;   (b) crossing the hybrid plant with itself or a distinct plant; and   (c) selecting a progeny plant produced from step (b) wherein genetic recombination has occurred between said first locus and said second locus to produce a megalocus comprising the first and second loci arranged in cis.   
     
     
         2 . The method of  claim 1 , further comprising:
 (d) obtaining a further hybrid plant comprising said megalocus and a third locus, where the third locus is transgenic, where the megalocus and third locus are located on different homologous chromosomes, and wherein the megalocus and third locus are at genetically linked positions in said homologous chromosomes;   (e) crossing the further hybrid plant with itself or a distinct plant; and   (f) selecting a further progeny plant produced from step (e) wherein genetic recombination has occurred between said megalocus and said third locus to produce a further megalocus comprising the first, second and third loci arranged in cis.   
     
     
         3 . The method of  claim 2 , wherein steps (d)-(f) are repeated 2 or more times with still further hybrid plants comprising additional loci, where the additional loci are transgenic, to obtain yet a further megalocus comprising the first through third loci and the additional loci arranged in cis. 
     
     
         4 . The method of  claim 1 , wherein obtaining the hybrid plant comprises crossing a first plant comprising the first locus with a second plant comprising the second locus. 
     
     
         5 . The method of  claim 1 , wherein the loci of the megalocus are genetically linked but physically separate. 
     
     
         6 . The method of  claim 1 , wherein said chromosome is a supernumerary chromosome. 
     
     
         7 . The method of  claim 6 , wherein said supernumerary chromosome is a B chromosome. 
     
     
         8 . The method of  claim 6 , wherein said supernumerary chromosome is an artificially derived chromosome. 
     
     
         9 . The method of  claim 8 , wherein said artificially derived chromosome is a truncated chromosome. 
     
     
         10 . The method of  claim 8 , wherein said artificially derived chromosome is a de novo generated chromosome. 
     
     
         11 . The method of  claim 4 , further comprising one or both of
 (i) transforming said first plant or a progenitor thereof with a transgene to produce said first locus; or   (ii) transforming said second plant or a progenitor thereof with a transgene to produce said second locus;   wherein said transforming occurs prior to step (a).   
     
     
         12 . The method of  claim 11 , wherein said transforming comprises site-specific introduction of a transgene to produce the first locus at a position genetically linked with said second locus. 
     
     
         13 . The method of  claim 1 , wherein said genetic recombination comprises meiotic recombination or induced recombination. 
     
     
         14 . The method of  claim 1 , wherein the loci of the megalocus are located about 0.1 cM to about 20 cM apart from each other. 
     
     
         15 . The method of  claim 1 , wherein the loci of the megalocus are located about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 5, 10, 15 or 20 cM apart from each other. 
     
     
         16 . The method of  claim 1 , wherein neutral or favorable loci are located between the loci of the megalocus. 
     
     
         17 . The method of  claim 1 , wherein said progeny plant produced from step (b) is hemizygous for said megalocus. 
     
     
         18 . The method of  claim 1 , wherein said progeny plant produced from step (b) is homozygous for said megalocus. 
     
     
         19 . The method of  claim 1 , wherein said megalocus is introgressed into a plant of the same variety as said first plant or a distinct variety from said first plant. 
     
     
         20 . The method of  claim 19 , wherein said introgression comprises a haploid induction cross. 
     
     
         21 . The method of  claim 1 , wherein said megalocus is introgressed into a plant of a distinct species from said first plant. 
     
     
         22 . A chromosome comprising the megalocus produced by  claim 1 . 
     
     
         23 . The chromosome of  claim 22 , wherein the chromosome is a supernumerary chromosome. 
     
     
         24 . The supernumerary chromosome of  claim 23 , wherein the supernumerary chromosome does not exhibit non-disjunction. 
     
     
         25 . A transgenic plant, seed or plant part comprising the megalocus produced by the method of  claim 1 . 
     
     
         26 . A method of producing a megalocus in a region of a chromosome lacking spontaneous meiotic recombination, comprising:
 (a) obtaining a hybrid plant comprising a first locus and a second locus, where the first locus is transgenic and the second locus comprises an endogenous trait locus or is transgenic, where the first and second loci are located on different homologous chromosomes, wherein the loci are located in a region of said homologous chromosomes lacking spontaneous meiotic recombination;   (b) inducing genetic recombination to occur between said first and second loci;   (c) crossing the hybrid plant with itself or a distinct plant; and   (d) selecting a progeny plant comprising a megalocus comprising the first and second loci located in cis within said region.   
     
     
         27 . The method of  claim 26  further comprising:
 (e) obtaining a further hybrid plant comprising said megalocus and third locus, where the third locus is transgenic, where the megalocus and third locus are located on different homologous chromosomes and within said region lacking spontaneous meiotic recombination; 
 (f) inducing genetic recombination to occur between said megalocus and third locus; 
 (g) crossing the further hybrid plant with itself or a distinct plant; and 
 (h) selecting a further progeny plant comprising a further megalocus comprising the first, second and third loci located in cis within said region. 
 
     
     
         28 . The method of  claim 27 , wherein steps (e) and (h) are repeated 2 or more times with still further hybrid plants comprising additional loci, where the additional loci are transgenic, to obtain yet a further megalocus comprising the first through third loci and the additional loci arranged in cis within said region. 
     
     
         29 . The method of  claim 26 , wherein said chromosome is a supernumerary chromosome. 
     
     
         30 . The method of  claim 26 , wherein said chromosome is a nuclear chromosome. 
     
     
         31 . The method of  claim 26 , wherein the loci of the megalocus are genetically linked but physically separate. 
     
     
         32 . The method of  claim 26 , wherein the region lacks spontaneous meiotic recombination due to a chromosomal rearrangement. 
     
     
         33 . The method of  claim 32 , wherein the chromosomal rearrangement is an inversion or a translocation. 
     
     
         34 . The method of  claim 26 , wherein said genetic recombination comprises induced meiotic recombination or chromosomal rearrangement. 
     
     
         35 . The method of  claim 26 , further comprising one or both of:
 (i) transforming said first plant or a progenitor thereof with a transgene to produce said first locus; or   (ii) transforming said second plant or a progenitor thereof with a transgene to produce said second locus;   
       wherein said transforming occurs prior to step (a). 
     
     
         36 . The method of  claim 34 , wherein said transforming is site-specific. 
     
     
         37 . The method of  claim 26 , wherein neutral or favorable loci are located between the loci of the megalocus. 
     
     
         38 . The method of  claim 26 , further comprising introgressing the megalocus into a plant of a different variety. 
     
     
         39 . The method of  claim 38 , wherein said introgressing comprises a haploid induction cross. 
     
     
         40 . The method of  claim 26 , comprising introgressing the megalocus into a plant of a different species. 
     
     
         41 . A chromosome comprising a megalocus produced by the method of  claim 26 . 
     
     
         42 . A transgenic plant, seed or plant part comprising a megalocus produced by the method of  claim 26 .