Transgenic plants .

1. AGROBACTERIUM MEDIATED
GENE TRANSFER

2. Agrobacterium mediated gene transfer
 Agrobacterium -mediated plant genetic transformation is
a multistep process in which the bacterium delivers a
specific DNA molecule from its own genome into the host-
cell genome.
 A. tumefaciens is a soil microorganism that causes CROWN
GALL DISEASE.
 Crown gall occurs when a wound on stem allows A.
tumefaciens bacteria to invade the plant.
 After the infection the bacteria cause a cancerous
proliferation of the stem region of the crown.

4. PLASMID

5. REGION A : T-DNA
 LB : Conserved sequence ( 24-25 bp repetitive sequence)
- present at 5’ end of ss T-DNA
 RB : : Conserved sequence ( 24-25 bp repetitive sequence)
- present at 3’ end of ss T-DNA
 Onc region : oncogene is responsible for tumor formation .
- it contains Auxins & Cytokinins
 Opine synthesis gene : rare kind of sugars
- source of carbon metabolism

6. REGION D : Vir genes
 Virulence gene
 24 genes
 Virulence genes are located in 8 operons from Vir A to Vir H.
 Vir A senses acetosyringone , and by phosphorylating activates vir G genes
which in turn activates all other vir genes.
 Dicotyledons secretes more phenolic substance

7.  Disarm the plasmid , remove tumor inducing portion.
 In place of oncogene place gene of interest ( gene cassets)
 Gene cassets : promoter, GOI , marker genes , terminator.
 CRY GENES : INSECT RESISTANCE
 CHITENASE GENE : FUNGAL RESISTANCE
 Mtl D ( mannitol-1-phosphate dehydrogenase) : abiotic stress
tolerance.

8. Plasmid (engineered with gene of interest)
Add acetosyringone( agrobac. Growth culture )
add explant of interest ( eg. Rice seed , rice embryos)
transfer explants to co culture medium ( explant & bacteria both grows ;
transformation takes place
transfer explants to callus induction medium
REGENERATION
MULTIPLE SHOOTS
ROOT INDUCTION
PLANTLETS

9. ADVANTAGES
 Simple and comparatively less expensive
 High transformation efficiency
 Transgenic crop obtained have better fertility percentage
 large length chromosomal segment can be transferred with little arrangement
DISADVANTAGES
 Time consuming
 Not all kind of cells can be treated by this method
 Can not transform organelles
 Sometimes leads to false positive results