Methods and composition for transferring T-DNA into a plant
The present disclosure provides a series of mutant Agrobacterium strains generated by random mutagenesis of a wide-type or ω mutant VirD2 gene or VirD2 protein. The mutant Agrobacterium strains of the present disclosure transiently express T-DNA-encoded transgenes in a target plant but do not stably integrate these genes into the plant genome.
1 . An Agrobacterium strain comprising a VirD2 gene mutant that effects efficient transient transformation of a plant cell, wherein said Agrobacterium strain has at least 5− to 50-fold less stable transformation than an Agrobacterium comprising a wild-type VirD2 amino acid sequence or no stable transformation, and said VirD2 gene mutant mutation results in an amino acid substitution of His 402 Arg in the amino acid sequence encoded by said VirD2 gene mutant;
wherein transient transformation comprises transferring, but not integrating, T-DNA into a plant cell inoculated with the Agrobacterium strain; and
wherein the mutant VirD2 gene of said strain further comprises a replacement of a final stop codon of the VirD2 gene mutant with a polynucleotide which encodes a polypeptide comprising the amino acid sequence of SEQ ID NO: 17.