The document summarizes key information about the Ti plasmid found in Agrobacterium tumefaciens bacteria. Some key points: 1) Ti plasmid is found in A. tumefaciens, a soil bacterium that can naturally transform plant cells and cause crown gall tumors through T-DNA integration into the plant genome. 2) The Ti plasmid contains a T-DNA region flanked by left and right border sequences that is transferred to plant cells. The T-DNA contains genes encoding hormones and opines. 3) Ti plasmids can be classified based on the type of opine gene present (nopaline, octopine, agropine). Ti plasmids are

1. Ti PLASMID
Shirin Shahana.N
3 yr-Bsc.Biotechnology
SIAS

2. PLASMIDS
•Plasmids are double stranded , closed circular DNA
molecules , which exist in the cell as extra
chromosomal units.
•These are transmitted from one bacterium to
another ( even of another species ) via horizontal
gene transfer.
•Engineered plasmids are widely used as vectors in
DNA cloning.Eg:Ti plasmid

3. Ti PLASMID
•Ti plasmid is a tumor - inducing plasmid or tumor
induction plasmid.
•It is found in Agrobacterium tumefaciens bacteria .
•It is a gram - negative soil bacterium which naturally
transforms plant cells,resulting in crown
gall(cancer)tumors.
•They infects plants through breaks or wounds .
•Tumor formation is the result of integration of T -
DNA ( Transfer DNA ) in plant genome .

5. Ti PLASMID & VIRULENCE GENES
•The 3 imoprtant regions of Ti plasmid:-
1)T-DNA region
•This region has the genes for the biosynthesis . of
anxin ( anxcytokinin ( W ) and opine ( cs ) , and is
flanked by left and right borders.
•T- DNA borders:-A set of 24 kb sequences present
on either side ( right & left ) of T - DNA are also
transferred to the plant cells.
•It is clearly established that the night border is more
entical for ' T - DNA transfer .

8. • Ti plasmids can be classified according to the opines
produced:-
• 1. Nopaline plasmids:-Carry gene for synthesizing
nopaline in the plant and for utilization ( catabolism ) in
the bacteria .
• 2. Octopine plasmids:-Carry genes to synthesize octopine
in the plant and catabolism in the bacteria .
• 3. Agropine plasmids:-Carry genes for agropine synthesis
and catabolism .

10. Ti plasmid-Derived Vector Systems
• Using Ti plasmid as a vector it is possible to insert a
desired DNA sequence ( gene ) into the TDNA
region of Ti plasmid.
• There are several limitations to use Ti plasmids
directly as cloning vectors due to:- -
• 1)Large size.
• 2)Tumour induction property.
• 3)Absence of unique restriction sites.

12. Agrobacterium mediated
transformation
• The important requirements for Agrobacterium
mediated gene transfer in higher plants are as
follows :-
• 1)The plant explants must produce acetosyringone
for activation of Vir genes .
• 2)The induced Agrobacterium should have access
to cells that are competent for transformation.
• 3)Explants include cotyledon,leaf,thin tissue
layer,peduncle,hypocotyls,stem,microspores.

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