Final answer:
The VirD2 and VirE2 proteins contain nuclear localization sequences that direct T-DNA to the plant nucleus. This process, facilitated by the Ti plasmid from Agrobacterium tumefaciens, is crucial for genetic engineering in plant cells.
Step-by-step explanation:
The proteins that contain nuclear localization sequences (NLS) that target the T-DNA to the plant nucleus are the VirD2 and VirE2 proteins. These proteins are part of the Ti plasmid system, which is utilized by Agrobacterium tumefaciens to transfer genetic material to dicotyledon plants. The use of Ti plasmids by researchers is instrumental in recombinant DNA technology, allowing the introduction of new genes into plant cells. The NLS is a peptide sequence that directs the nuclear import of the protein by mediating its interaction with the nuclear pore complexes.
In the case of the Ti plasmid, the T-DNA region containing the NLS is integrated into the plant cell's genome, leading to various genetic modifications like herbicide resistance or the production of novel proteins. This has significant applications in agricultural biotechnology, such as the development of transgenic crops with desired traits.