Agrobacterium Gene Transfer Method PDF
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This document explains the Agrobacterium-mediated gene transfer method used in plant transformation. It details the steps involved, from bacterial attachment to T-DNA integration and expression in the plant genome. The process is crucial for introducing desirable genes into plants for various applications.
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**AGROBACTERIUM GENE TRANSFER METHOD** Agrobacterium tumefaciens is the most efficient vector used to plant transformation. *Agrobacterium tumefaciens* is a rod-shaded, gram-negative bacteria found in soil, and it is the natural causative agent for crown gall disease. *Agrobacterium tumefaciens*...
**AGROBACTERIUM GENE TRANSFER METHOD** Agrobacterium tumefaciens is the most efficient vector used to plant transformation. *Agrobacterium tumefaciens* is a rod-shaded, gram-negative bacteria found in soil, and it is the natural causative agent for crown gall disease. *Agrobacterium tumefaciens* is attracted to the amino acids, sugars, and organic acids released by the wounded plants. It binds the wounded tissue by a polar attachment mechanism. Steps for the transformation method 1. Attachment of agrobacterium to the plant 2. Sensing plant signals by agrobacterium and regulation of virulence genes 3. Generation and transportation of T-DNA and virulence proteins from bacterial cells to plant cells. 4. Nuclear import of T-DNA and effector proteins into the plant cell 5. T-DNA integration and expression in the plant genome  **Ti PLASMID** - Circular piece of DNA - Has three main regions 1. T-DNA region 2. Oncogene 3. Virulence region (24 genes) VIRULENCE GENES 1. VirA- senses acetosyringone 2. VirG- transcriptional activator of vir box 3. VirB- conjugates pores between plant cells and bacteria 4. VirD1- cleavage of a supercoiled stranded substrate 5. VirE- responsible for gene transfer protein 6. VirC- helps in DNA transfer 7. VirB11 ATPase activity- provides energy for DNA MODE OF ACTION 1. Plant begins to divide and form tumors 2. They begin to synthesize an arginine derivative called opine (opine is used as an energy source by infecting bacteria) 3. The entry of bacterium is facilitated by the release of phenolic compounds (acetosyringone) 4. Acetosyringone activates virulence 5. Vir proteins synthesize single-stranded T-DNA 6. T-DNA s transferred to the plant cell from bacterial cell 7. T-DNA complex import to nucleus and integration in random sits in chromosomes of plant 8. Synthesis of auxin and cytokinin promoting tumor formation in agrobacterium infected plant cells.
