This document summarizes Agrobacterium-mediated gene transfer. It begins with an introduction to gene transformation and describes Agrobacterium as a soil bacterium that causes crown gall disease in plants by transferring genes. It then discusses the classification of Agrobacterium, the history of using Agrobacterium for gene transfer, and components involved like the T-DNA, virulence genes, and chromosomal genes. The document outlines the process of T-DNA transfer from Agrobacterium to plant cells and concludes with some common methods for Agrobacterium-mediated gene transfer.

1. AGROBATERIUM MEDIATED
GENE TRANSFER
BY M.sobika
III B.sc Biotechnology
Ayya Nadar Janaki Ammal College
,Sivakasi.

2. CONTENTS
Introduction to gene transformation.
Agrobacterium general introduction.
Classification of agrobacterium.
History of agrobacterium mediated gene transformation.
T-DNA .
Virulence genes .
Chromosomal genes .
Agrobacterium tumefaciens T-DNA transfer process.
Method of agrobacterium tumefaciens .
References.

3. GENE TRANSFER INTRODUCTION
 Gene transfer is to transfer a gene from one
DNA molecule to another DNA molecule .
The direct desirable gene transfer from one
organism to another and the subsequent
stable integration & expression of foreign gene
into the genome is referred as genetic
transformation .
Transient transformation occur when DNA is
not integrated into host genome

4. Agrobacterium mediated gene transfer
Agrobacterium:
Soil borne ,gram negative ,rod shape motile found in
rizosphere .
Causative agents of “crown gall "disease of
dicotyledons .
Have ability transfer bacterial genes to plant genome .
Attracted to wound site via chemotaxis in response
to chemical (sugar and phenolic molecules
:acetosyringone )released from damaged plant cells .
Contain Ti plasmid which can transfer its T-DNA
region into genome of host plants

7. CLASSIFICATION OF AGROBACTERIUM
Scientific classification
Kingdom :Bacteria
Phylum :Proteobacteria
Class : Alproteobacthaperia
Order :Rhizobiales
Family :Rhizobiaceae
Genus :Agrobacterium
Species :A. tunefaciens

8. HISTORY OF AGROBACTERIUM MEDIATED GENE
TRANSFORMATION:
Smith & Townsend ( 1907 ) –said bacteria
caused crown gall disease .
Brown & Stonier ( 1958 ) –proposed that
not whole bacteria but some part of it cause
disease .
Zenen et.al (1974 ) –noted virulent stain
Agrobacterium tunefaciens .
Chilton et.al ( 1977 ) –reported Ti & Ri
plasmid transfer to plant causing disease .

10. T-DNA
The transfer DNA ( T-DNA ) is the
transferred DNA .
The T-DNA initiates at right border and
terminates at left border .
Its about 24000 base pairs .
Contains genes for enzymes synthesizing
opiens and phytohormones .
It also contains a vir .

12. AGROBACTERIUM TUNEFACIENS T-DNA
TRANSFER PROCESS

13. VIRULENCE GENES
Virulence region consists of 24 genes in total
Virulence genes are located in 8 operons from virA-virH
Vir A vir F and vir G are monocistronic operons, where as
vir B,C,D,E,H are polycistronic
Vir A senses Acitosyringone
Vir G transcriptional activator of vir box
Vir B conjugational pores between plant cell and bacteria
Vir D1 essential for cleavage of super coiled stranded
substrate
Vir E responsible for gene transfer protein
Vir C helps in DNA transfer
Vir B11 ATPase activity –provides energy for DNA

15. CHROMOSOMAL GENES

17. AGROBACTERIUM TUNEFACIENS T-DNA
TRANSFER PROCESS
Steps of gene transfer in plants
I. Bacterial clonization
II. Induction of virulence system
III. Generation of T-DNA transfer
complex
IV. T-DNA transfer
V. Integration of T-DNA into plants

18. METHODS OF AGROBACTERIUM TUMEFACIENS
GENE TRANSFER
Infection through wound
Leaf disk method
Co –cultivation