Fungal genome modification systems and methods of use
Compositions and methods are provided for genome modification at a target site in the genome of a fungal cell. The methods and compositions are drawn to a guide polynucleotide/Cas endonuclease system for promoting modification of the DNA sequence at a target site in a fungal host cell genome.
1. A method for modifying a DNA sequence at a target site in the genome of a filamentous fungal cell, the method comprising:
a) introducing into a population of filamentous fungal cells a Cas endonuclease and a guide RNA, wherein the Cas endonuclease and guide RNA are capable of forming a complex that enables the Cas endonuclease to introduce a double-strand break at a target site in the genome of the fungal cells, wherein the introducing step comprises introducing a DNA construct comprising an expression cassette for the guide RNA into the filamentous fungal cells, wherein the expression cassette for the guide RNA comprises a RNA polymerase III dependent promoter derived from a Trichoderma U6 snRNA gene and functional in a Euascomycete or Pezizomycete, and wherein the promoter is operably linked to the DNA encoding the guide RNA; and,
b) an identification step, the identifying step comprises culturing the population of cells from step (a) under conditions to screen for unstable transformants and identifying at least one fungal cell from the unstable transformants that has a modification of the DNA sequence at the target site,
wherein the Cas endonuclease, the guide RNA, or both are introduced transiently into the population of fungal cells, and wherein the modification of the DNA sequence at the target site is not caused by homologous recombination between a donor DNA and the genome of the filamentous fungal cell.
2. The method of claim 1 , wherein the promoter comprises a nucleotide sequence with at least 70% identity to SEQ ID NO: 11 or 12.
3. The method of claim 1 , wherein the expression cassette for the guide RNA comprises a guide RNA-encoding DNA with an intron sequence from a Trichoderma U6 snRNA gene.
4. The method of claim 3 , wherein the intron sequence derived from Trichoderma U6 snRNA gene comprises a nucleotide sequence with at least 70% identity to SEQ ID NO: 90.
5. An engineered nucleic acid encoding a guide RNA which enables a Cas endonuclease to introduce a double-strand break at a target site in the genome of a filamentous fungal cell, wherein the nucleic acid encoding the guide RNA comprises a RNA polymerase III dependent promoter functional in a Euascomycete or Pezizomycete, and the promoter is derived from a Trichoderma U6 snRNA gene.
6. The engineered nucleic acid of claim 5 , wherein the promoter comprises a nucleotide sequence with at least 70% identity to SEQ ID NO: 11 or 12.
7. An engineered nucleic acid encoding a guide RNA which enables a Cas endonuclease to introduce a double-strand break at a target site in the genome of a filamentous fungal cell, wherein the nucleic acid encoding the guide RNA comprises a guide RNA-encoding DNA with an intron sequence derived from a Trichoderma U6 snRNA gene.
8. The engineered nucleic acid of claim 7 , wherein the intron sequence derived from Trichoderma U6 snRNA gene comprises a nucleotide sequence with at least 70% identity to SEQ ID NO: 90.
9. The engineered nucleic acid of claim 5 or 7 , wherein the nucleic acid encoding the guide RNA comprises both a promoter derived from a Trichoderma U6 snRNA gene and an intron sequence derived from a Trichoderma U6 snRNA gene, wherein the promoter comprises a nucleotide sequence with at least 70% identity to SEQ ID NO: 11 or 12, and wherein the intron sequence derived from Trichoderma U6 snRNA gene comprises a nucleotide sequence with at least 70% identity to SEQ ID NO: 90.