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Agrobacterium tumefaciens

Agrobacterium tumefaciens. Agrobacterium tumefaciens is a Gram-negative soil phytopathogen. Agrobacterium tumefaciens. Agrobacterium affect most dicotyledonous plants in nature, resulting in crown gall tumors at the soil-air junction upon tissue wounding.

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Agrobacterium tumefaciens

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  1. Agrobacterium tumefaciens • Agrobacterium tumefaciens is a Gram-negative soil phytopathogen.

  2. Agrobacterium tumefaciens • Agrobacterium affect most dicotyledonous plants in nature, resulting in crown gall tumors at the soil-air junction upon tissue wounding.

  3. Agrobacteria that causes neoplastic diseases in plants • Agrobacterium rhizogenes (hairy root disease). • Agrobacteriumrubi (cane gall disease) • Agrobacteriumtumefaciens (crown gall disease) • Agrobacteriumvitis (crown gall of grape)

  4. What will Agrobacterium tumefaciens affect in plants? • Crown gall disease is not generally fatal, but it will reduce plant vigor and crop yield, and crown galls will attract other phytopathogens or pests. • In some cases, necrosis or apoptosis is observed after Agrobacterium infection.

  5. Host range of Agrobacterium • Agrobacterium has the broadest host range of any plant pathogenic bacterium. • Angiosperms: numerous species, including monocots and dicots. • Gymnosperms: mostly genus Pinus. There was a report about transforming larch (Larix) • Microorganisms: fungi, yeasts, ascomycetes, and blasidiomycetes. • Human cells: Hela cells

  6. The discovery of Agrobacterium • In 1897, Fridiano Cavara identified a flagellate, bacilloid bacterium as a casual agent of crown gall of grape. • This organism is Agrobacterium vitis, causing the growth of neoplastic tumors on the stem and crown of grapevines and inducing necrotic lesions on grape roots.

  7. The initiation of Agrobacterium infection • Agrobacteria usually infects plants from their wounds, which occurred quite frequent after frost. • In practice, protection from subfreezing winter temperatures and control of chewing insects and nematodes can prevent infection by agrobacteria. • Avirulent Agrobacterium strains like Agrobacterium radiobacter K84 and its plasmid-transfer-deficient derivative K1026 strains were proven to be effective in controlling infection.

  8. Agrobacterium infect the ovaries of flowers • Agrobacterium infects flowers that were developmentally young at the time (6-11 days away from anthesis; equivalent to 5-10 days after inoculation).

  9. Agrobacterium infect the ovaries of flowers • GUS staining can only be observed in ovaries 5 days after inoculation and is vanished 12 days after inoculation.

  10. How can Agrobacterium infects the ovaries of flowers? • Because the gynoecium of Arabidopsis were formed by two carpels and they remained separated until three days before anthesis (flowering).

  11. Agrobacterium tumefaciens 膿桿菌

  12. transfer Left Border and Right Border (Tumor-inducing)

  13. Binary vector system

  14. Steps of Agrobacterium-plant cell interaction • Cell-cell recognition • Signal transduction and transcriptional activation of vir genes • Conjugal DNA metabolism • Intercellular transport • Nuclear import • T-DNA integration

  15. T-pilus usually wind into compact coils to bring the bacterium and host cell closer

  16. CaMV 35S PR Right T-DNA border MCS nptII(KanR) Neomycin phosphotransferase Left T-DNA border

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