PLP407 Lecture 15
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- Describe an existing method for controling a plant disease using a biocontrol agent.
- The crown gall disease (Agrobacterium tumefacians) is controlled by dipping the roots of the stock in Agrobacterium radiobacter (non-pathogenic or gall forming Agrobacterium)so that the infection sites are outcompeted.
- How do bacteria enter a plant and cause infections?
- Bacteria cannot force their way into the plant so they must enter through the lenticles, stomates, wound sites, and/or nectaries
- How would you tell the difference between a gall formed by a bacterium and one formed by a genetic factor?
- The gall formed by a bacterium is soft and punky whereas one formed by a genetic defect is hard and woody.
- Where on a plant would you be likely to find an Agrobacterium canker?
- At or below the soil line
- Which family is most suseptable to agrobacterium infection?
- Rosaceae
- Fire blight and bacterial blight of lilac, blast the flowers and new shoots. What is the source of the inoculum that infects during the spring? How does the disease spread?
- The slimy margin of the bacterial canker is the source and transportation is done by pollenators and rain-splash.
- List four symptoms that bacterial disease can cause in plants.
- Leaf spot galls soft shoots wilt root noduals Stem and shoot rots o Leaf blight and spots o Galls o Soft roots (of fruits of herbaceous plants) o Wilts (primarily herbaceous) o Stem and shoot rots (herbaceous) o Root nodules (woody plants)
- How does agrobacterium tumefacians cause the gall growth?
- The plasmids in the bacteria combine with the DNA of the plant and cause rapid differentiation of cells
- What bacterial infection is most commonly found in elms? Cherries?
- Slime flux in elm caused by bacterial wetwood Cherry- Bacterial chanker caused by pseudomonas syringae
- What 2 types of prokaryotes cause the bacterial slime flux in elms?
- Eubacteria and archaea