Methods for producing genetic modifications in a plant genome without incorporating a selectable transgene marker, and compositions thereof
Compositions and methods are provided for genome modification of a target sequence in the genome of a plant or plant cell, without incorporating a selectable transgene marker. The methods and compositions employ a guide polynucleotide/Cas endonuclease system to provide an effective system for modifying or altering target sites within the genome of a plant, plant cell or seed, without incorporating a selectable transgene marker. Once a genomic target site is identified, a variety of methods can be employed to further modify the target sites such that they contain a variety of polynucleotides of interest. Breeding methods and methods for selecting plants utilizing a guide polynucleotide/Cas endonuclease system are also disclosed. Compositions and methods are also provided for editing a nucleotide sequence in the genome of a cell, without incorporating a selectable transgene marker.
1. A method for producing a second generation of soybean plant that comprises herbicide resistance, the method comprising:
(a) stably integrating a polynucleotide encoding a Cas endonuclease within a genome of a first soybean plant cell,
(b) introducing a first guide polynucleotide, a polynucleotide modification template, and a second guide polynucleotide into the first soybean plant cell;
wherein said first guide polynucleotide and Cas endonuclease are capable of forming a first complex that enables the Cas endonuclease to introduce a double strand break at a first target site, located in or near a endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene, in the genome of said first soybean plant cell;
wherein said second guide polynucleotide and Cas endonuclease are capable of forming a second complex that enables the Cas endonuclease to introduce a double strand break at a second target site in the genome of said first soybean plant cell;
wherein said polynucleotide modification template causes a deletion of the native promoter of the endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene with the insertion of a heterologous promoter and at least one nucleotide alteration when compared to the endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene, and; wherein said at least one nucleotide alteration encodes for an amino acid change in the endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene,
(c) producing a genetic modification within said endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) of the first soybean plant cell genome without introducing an exogenous selectable marker into the first or second target site of said first soybean plant cell genome, wherein the first soybean plant cell comprises a modified endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene that confers herbicide resistance,
(d) generating a first generation soybean plant from the first soybean plant cell,
(e) crossing the first generation soybean plant with a second soybean plant to produce a second generation soybean plant; wherein the second generation of soybean plant comprises in its genome a modification of a gene corresponding to said endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene and a modification at a site corresponding to the second target site; wherein said modification of a gene corresponding to said endogenous enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene confers herbicide resistance to the second generation of soybean plant.
2. The method of claim 1 , wherein the first target site and the second target site are located at two different genomic loci.
3. The method of claim 1 , wherein the Cas endonuclease is a Cas9 endonuclease.
4. The method of claim 1 , further comprising selecting at least one soybean plant cell that has resistance to a glyphosate herbicide and comprises a modification of said second target site, wherein said modification includes at least one deletion, insertion or substitution of one or more nucleotides in said second target site of the soybean plant genome.
5. The method of claim 4 , wherein said modification of said second target site includes at least one deletion, insertion, or substitution of one or more nucleotides in a Fatty Acid Desaturase 2-1 (FAD2-1) gene.
6. The method of claim 5 , further comprising producing a soybean plant from said soybean plant cell, wherein said soybean plant has resistance to said glyphosate herbicide and has a high oleic phenotype due to the at least one deletion, insertion, or substitution of one or more nucleotides in said Fatty Acid Desaturase 2-1 (FAD2-1) gene.