Enhanced plant regeneration and transformation by using GRF1 booster gene

A method for modifying the genome of a Zea mays plant cell, comprising the steps:

• (a) introducing into the Zea mays plant cell an expression cassette comprising a polynucleotide encoding a growth-regulating factor 1 (GRF1) polypeptide, mRNA encoding a GRF1 polypeptide, or GRF1 polypeptide(s);
• and
• (b) cultivating the Zea mays plant cell of (a) or a plant cell derived from the plant cell of (a) under conditions where in the Zea mays plant cell the GRF 1 polypeptide is expressed from the expression cassette, GRF 1 polypeptide is translated from introduced mRNA, GRF 1 polypeptide is expressed from the endogenous gene, or GRF 1 polypeptide(s) are present;
• (c) modifying the genome of the Zea mays plant cell of (b) by means of a single stranded DNA break (SSB) or double stranded DNA break (DSB) inducing enzyme or a base editor enzyme which recognizes a predetermined site in the genome of said Zea mays plant cell, and optionally by means of a repair nucleic acid molecule, wherein the modification of said genome at said predetermined site is selected from:
• i) a replacement of at least one nucleotide;
• ii) a deletion of at least one nucleotide;
• iii) an insertion of at least one nucleotide;
• or
• iv) any combination of i)-iii);
• and
• wherein step (c) is conducted simultaneously with step (a) and/or (b), before step (a), between step (a) and (b) or after step (b),
• wherein the polynucleotide encoding the GRF 1 polypeptide comprises the coding nucleotide sequence of SEQ ID NO:
• 1,
• wherein the presence of the GRF1 polypeptide in the Zea mays plant cell results in at least a two-fold increase in transformation efficiency relative to an otherwise identical Zea mays plant cell that does not comprise the GRF 1 polypeptide,
• wherein step (a) further comprises introducing an expression cassette comprising a polynucleotide encoding a Wuschel2 (WUS2) polypeptide, a mRNA encoding a WUS2 polypeptide, or WUS2 polypeptide(s), and
• wherein co-expression of the GRF1 polypeptide and the WUS2 polypeptide results in enhanced regeneration capability relative to regeneration capability resulting from co-expression of the WUS2 polypeptide and a Zea mays Plethora 7 (ZmPLT7) polypeptide.