Methodologies and compositions for creating targeted recombination and breaking linkage between traits
The current disclosure relates to methods and compositions for improving plant varieties through plant breeding and plant genetics. For instance, the disclosure concerns increasing the recombination frequency of a heterozygous trait genetically linked to a second trait within plants. Further, the disclosure concerns breaking the genetic linkage between a first allele and a second allele.
1 . A method for increasing the frequency of genetic recombination between a first locus genetically linked to a second locus within a genome of a plant, the method comprising the steps of:
a) introducing a site specific nuclease into the genome of the plant;
b) producing a double stranded break at a genomic target site with the site specific nuclease in one of two homologous chromosomes, wherein the double stranded break is produced by a site specific nuclease in one of two homologous chromosomes, and a double stranded break is not produced in the second homologous chromosome;
c) undergoing recombination within the plant genome; and,
d) modifying the plant genome, wherein the modified plant genome comprises increased frequency of genetic recombination between the first locus and the second locus to reduce the genetic linkage between the first locus and the second locus.
2 . The method of claim 1 , wherein the first locus encodes a trait and the second locus encodes a different trait.
3 . The method of claim 1 , wherein recombination comprises meiotic recombination or mitotic recombination.
4 . The method of claim 1 , wherein the increased frequency of genetic recombination ranges from 1.25 to 17.8 fold.
5 . The method of claim 1 , wherein the distance from the first locus to the second locus ranges from about 0.01 CM to about 500 CM.
6 . The method of claim 1 , wherein the distance from the first locus to the second locus ranges from about 10 bp to about 10 Mbp.
7 . The method of claim 1 , wherein the first locus is located on a first chromosome, and the second locus is located on a second chromosome.
8 . The method of claim 1 , wherein the first locus and the second locus are present in a genomic location with low levels of recombination frequency.
9 . The method of claim 2 , wherein the trait comprises a desirable trait or an undesirable trait.
10 . The method of claim 9 , wherein the desirable trait or the undesirable trait is either a native trait or a transgenic trait.
11 . The method of claim 10 , wherein the undesirable trait is selected from the group consisting of reduced yield, reduced resistance to disease, reduced resistance to pests, reduced tolerance to herbicide tolerance, reduced growth, reduced size, reduced production of biomass, reduced amount of produced seeds, reduced resistance against salinity, reduced resistance against heat stress, reduced resistance against cold stress, reduced resistance against drought stress, and any combination thereof.
12 . The method of claim 10 , wherein the desirable trait is selected from the group consisting of increased yield, increased resistance to disease, increased resistance to pests, increased tolerance to herbicides, increased growth, increased size, increased production of biomass, increased amount of produced seeds, increased resistance against salinity, increased resistance against heat stress, increased resistance against cold stress, increased resistance against drought stress, and any combination thereof.
13 . The method of claim 1 , wherein the first locus comprises a polymorphic marker and the second locus comprise a trait.
14 . The method of claim 1 , wherein the first locus comprises a polymorphic marker and the second locus comprises a polymorphic marker.
15 . The method of claim 1 , wherein the site specific nuclease is selected from the group consisting of a zinc finger nuclease, a TALEN nuclease, a CRISPR nuclease, a meganuclease, and a leucine zipper nuclease.
16 . The method of claim 1 , wherein the site specific nuclease is delivered to a cell by intragenomic recombination or via direct delivery.
17 . The method of claim 1 , wherein the genome of the plant is a polyploid.
18 . The method of claim 1 , the method further comprising the steps of:
e) producing a progeny plant comprising the modified plant genome;
f) crossing the progeny plant with another plant or to itself; and,
g) generating a seed from the progeny plant.
19 . The method of claim 2 , wherein the first locus comprising a first trait is located on the first homologous chromosome and the second locus comprising a second trait is located on the first homologous chromosome.
20 . The method of claim 8 , wherein the resulting double strand break occurs between the first locus comprising the first trait and the second locus comprising the second trait, thereby resulting in a progeny plant comprising only the first locus comprising the first trait.
21 . The method of claim 2 , wherein the first trait is either a recessive or a dominant trait.
22 . The method of claim 2 , wherein the first trait is either a heterozygous or a homozygous trait.
23 . The method of claim 1 , wherein the plant is selected from a dicotyledonous plant or a monocotyledonous plant.
24 . The method of claim 23 , wherein the plant is selected from the group consisting of a tobacco plant, a soybean plant, a cotton plant, a Brassica plant, a corn plant, a sorghum plant, a wheat plant, and a rice plant.