The document summarizes the process of T-DNA transfer and integration during Agrobacterium infection of plant cells. It describes how Agrobacterium recognizes plant signals, induces virulence genes, produces single-stranded T-DNA, transfers T-DNA into the plant cell attached to VirD2 and wrapped in VirE2, and how the T-DNA complex enters the plant cell nucleus and integrates into the plant genome through illegitimate recombination with the help of VirD2, VirE2, and plant proteins like VIP1 and VIP2.

1. The Process of T-DNA
Transfer and Integration
Presented by: Zohaib
Hussain

2. Signal Recognition by
Agrobacterium
Phenolics
/Sugars
Signal
(competent
cells)
Plant
defense
mechanisms

3. Attachment
Polysaccharide
(attR locus)
Cellulose mesh
Virulence gene
(chvA and
chvB)
pscA
(succinoglycan)

4. Vir Gene Induction
• Vir A
• Auto-
phosphorylates
Membrane linked
sensor kinases
• Vir G
• Phosphorylates
Activates
• All vir genes
• Vir A and Vir G
Induces
*chvE glucose/galactose transporter

5. T- Strand Production
VirD1/VirD2
Complex
Left/right
borders T-
DNA
VirD2
1. Produce
single Stranded
nicks
2. Covalently
linked to 5’ end
of T-DNA
*VirC1 repair sythesis

7. Transfer of T-DNA out of B-
Cell
Cytoplasm
VirE2
T-
DNA/Vir
D2
comple
x
T pilus
*Vir B operon
and VirD4

8. T-DNA into Plant Cell and Nuclear
Localization
T-DNA Strand
covered with
VirE2
Protect the T-
DNA from
nucleases
Nuclear
localization
Correct
conformation
for passage
through NPC

9. Nuclear localization
 VirD2 and VirE2 interacts with variety
of plant proteins
 Ensuring nuclear localization of T-DNA
Complex

10. VirD2
NLS
Facilitates its
interaction with
plant protein
Importins
Recognition
and transport
through NPC
Only those
proteins that
possess NLS
VirE2
Two NLS
Mediated by
another plant
protein
VIP1
Nuclear localization

11. Entry
 T-DNA and associated proteins pass
through the nuclear pore with bound
VirE2 proteins
 Correct conformation to the T-DNA
strand

12. Integration
.
VIP1 and
VIP2
.
Direct DNA
Strand to
chromatin
Promote
integration
.
Illegitimate
recombination

15. Thanks