The document discusses gene transfer in plants through recombinant DNA technology, highlighting various methods, including agrobacterium-mediated transformation. It provides details on the mechanisms by which agrobacteria colonize plant cells and transfer T-DNA, resulting in genetic modifications. Additionally, it outlines the advantages of different bacterial species and plasmids involved in this process for crop improvement.

1. Gene transfer in plants

2. Recombinant DNA technology and
crop improvement
Allows utilization
of every species
Allows direct
transfer of a single
gene
Requires a
method of gene
transfer into plant
cell
Requires
regenerable plant
cells

3. Plants can be improved through different
ways
Conventical
plant
breeding
Tissue
culture
Genetic
engineering
Gene editing

4. Plant transformation
methods
Direct
particle
bombardment/gene
gun
Electroporation liposomes silicon carbide microinjection
Indirect genetic
transformation
Agrobacterium-
mediated gene
transfer

5. Agrobacterium is the only cellular organism on Earth that is naturally capable of
transferring genetic material between the kingdoms of life, from prokaryotes to
eukaryotes

6. Plant transformation methods
Physical Chemical
Biological In planta

7. Plant transformation methods
Biological
Agrobacterium
Agrobacterium tumefaciens Agrobacterium rhizogenes
• Gram-negative
bacteria in soil
• Unique bacterial
species crown gall disease hairy root disease

8. Agrobacterium tumefaciens
• Soil bacterium closely related to Rhizobium
• Causes crown gall disease in plants (dicots)
• Infects at root crown or just below the soil line.
• Can survive independently of plant host in the
soil.
• Infects plants through breaks or wounds.
• A common disease of woody shrubs, and
herbaceous plants, particularly problematic
with many members of the rose family.
Galls are spherical
wart-like structures
similar to tumors

9. phytopathogen
infects plants
through wounded
tissues, resulting in
crown gall or hairy
root diseases. It is an
aerobic, Gram-
negative rod-shaped
bacterium and is
motile with one or as
many as six flagella
per cell

10. Agrobacterium tumefaciens
chromosomal genes:
• chvA
• chvB
• pscA
required for initial binding of the
bacterium to the plant cell and code
for polysaccharides on bacterial cell
surface

11. occ (opine catabolism)
genes carried on the pTi
and allows the
bacterium to utilize
opines as nutrient

13. Five essential steps gene transfer from
Agrobacterium to plant cells
bacterial
colonization
Induction of
bacterial
virulence
system
Generation
of T-DNA
transfer
complex
Transfer of T-
DNA
Integration of
T-DNA into
the plant
genome

14. 1.bacterial
colonization
2.Induction of bacterial
virulence system
3.Generation of T-DNA
transfer complex
4.Transfer of T-
DNA 5.Integration of T-DNA
into the plant genome

16. Agrobacterium tumefaciens

17. Ti plasmids classified according to
opine produced
Noplaline plasmids
carry genes for
synthesizing nopaline in
the plant and for
utilization (catabolism)
in the bacteria.
Tumors can
differentiate into shooty
masses (teratomas)
Octapine plasmids
carry genes(3 required)
to synthesize octopine
in the plant and
catabolism in the
bacteria.
Tumors do not
differentiate but remain
as callus tissue.
Agropine plasmids
carry genes for
agropine synthesis and
catabolism.
Tumors do not
differentiate and die out

18. Plant transformation methods
Biological
Agrobacterium
Agrobacterium tumefaciens Agrobacterium rhizogenes
• Gram-negative
bacteria in soil
• Unique bacterial
species crown gall disease hairy root disease

19. Agrobacterium rhizogenes
• capable of entering a plant through a wound and causing a
proliferation of secondary roots
• Hairy roots are unique in their genetic and biosynthetic
stability. Their fast growth, low doubling time, ease of
maintenance, and ability to synthesize a range of chemical
compounds offer an additional advantage as a continuous
source for the production of valuable secondary
metabolites
• Hairy roots display stable phenotypes over multiple
generations (advantageous for studying gene function and
evaluating the effects of gene expression on plant traits)

20. Ri plasmids classified according to
opine produced
Agropine-type Ri-plasmid has 2
separate T-DNA regions:
TL-DNA (15-20Kb)
Nonintegrated plasmids DNA (15Kb)
TR-DNA (15-20Kb)
mannopine type Ri-plasmids
Has only one T-DNA (shares DNA
sequence homology with TL of the
agropine-type plasmids)
The complete nucleotide sequence of
the TL-region revealed the presence of
18 (ORFs), 4 of which, ORFs 10, 11,12
and 15, respectively, correspond to
the rolA,rolB, rolC, and rolD loci.

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