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7 Cards in this Set

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How do plant pathogens affect photosynthesis?
Interfere by chlorosis, necrosis, and reduced growth and yield
Reduce amount of photosynthetic surface
Affect chloroplasts--degeneration
Produce toxins that inhibit enzymes involved
Stomata remain partially closed, chlorophyll is reduced and photosynthesis stops
How do plant pathogens interfere with translocation of water and nutrients?
Affect the integrity of function of root- absorb less water
Growth in xylem vessels interfering with translocation
Interfere with water economoy of plant by causing excessive transpiration
Example: Fusarium crown rot
How do plant pathogens interfere with translocation in xylem vessels?
Physical presence (mycelium, conidia, bacterial cells) in xylem
Polysaccharides in the vessels
Collapse of vessels
Development of tyloses
Reduced water tension in vessels due to pathogen-induces alteration in foliar transpiration
How do plant pathogens interfere with translocation of nutrients through phloem?
Pathogen attacks and destroys phloem elements interferring with downward translocation of nutrients
Starch accumulation in the leaves is a result of degeneration of the phloem of infected plants (leaf curling viruses)
How do plant pathogens affect transpiration?
Increases when plant pathogens infect leaves because of an increase in leaf cell permaeability and stomata dysfunction
Destruction of a considerable portion of the cuticle and epidermis results in an uncontrolled loss of water from the affected areas
If water absorption and translocation cannot keep up with excessive loss of water, loss of turgor and wilting of leaves follow
How do plant pathogens affect respiration?
Rate of respiration increase when plants are infected.
Appears shortly after infection and continues to rise during muliplication and sporulation of the pathogen, increased respiration accompanied by increased activation of pentose pathway.
Increase in plant metabolism, plant growth is stimulated, protoplasmic streaming increases and material are synthesized, translocated and accumulated, energy for these activities is derived from ATP produced through respiration.
What is an example of a disease that affect cell membrane permeability?
gray leaf spot