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Effect of plant pathogens in plant physiologicalfunction
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- 2. INTRODUCTION Main pathogensare Virus Bacteria Fungi Physiological functions Photosynthesis Respiration Permeability of cell membrane Translocation of water and nutrients Transcription and translation 1/1/2017 2
- 3. PHOTOSYNTHESIS Interfere bychlorosis, necrosis, and reduced growth and yield Reduce amount of photosynthetic surface Produce toxins that inhibit enzymes involved Stomata remains unpartially closed chlorophyll is reduced photosynthesis stops 1/1/2017 3
- 4. Influence of virusinfection Reduce chloroplast amount Reduction in chlorophyll content Chloroplast abnormalities Reduction in photochemical activity Reduction in sucrose content 1/1/2017 4
- 5. Influence of bacterialinfection Decrease in chloroplast storma Disorientation of chloroplasts Destroy of chloroplast integrity - HR Suppression of CO2 fixation 1/1/2017 5
- 6. EFFECT OF FUNGALINFECTION Reduce chloroplast RNA content Loss of chlorophyll Inhibit photophosphorylation coupling mechanism Inhibit electron transport Suppress CO2 fixation 1/1/2017 6
- 7. RESPIRATION Respiration increasesduring pathogen attack Rate Continues to Rise during Multiplication and Sporulation of the Pathogen Declines to Normal or below-Normal Levels Rate Increases more Rapidly in Resistant Varieties Increased Respiration Depletes Plant’s Reserves Changes Metabolism 1/1/2017 7
- 8. Effect of viruses Non hypersensitive hosts Slightly increase in respiration rate of inoculated leaves Hypersensitive hosts A much more considerable increase in respiration activity than systemic hosts 1/1/2017 8
- 9. EFFECT OF BACTERIA Resistant tissue :Immediate increase in O2 consumption Susceptible tissue : Do not reflect an increase in respiration until about 30 hours after inoculation eg : pepper – Xanthomonas vesicatoria 1/1/2017 9
- 10. Effect of fungi Respiration rate is usually increased in diseased plants In the early stage of disease, synthetic processes induce high rates of respiration In the late stages injury and decomposition of tissues lead to increase respiration. 1/1/2017 10
- 11. MEMBRANE PERMEABILITY Pathogenschange the permeability by Mechanical injury Enzymatic degradation Toxins First detectable responses of cells Leakage of electrolytes Occur when host-pathogen interaction is incompatible 1/1/2017 11
- 12. TRANSLOCATION OF WATERAND NUTRIENTS Affect the function of root - absorb less water Growth in xylem vessels interfering with translocation Interfere with water economy of plant by causing excessive transpiration Eg :Fusarium crown rot 1/1/2017 12
- 13. EFFECT OF VIRUS Leads to a reduction in transpiration rate reduced leaf stomata aperture Accumulation of carbohydrates in leaf tissue Accompanied by phloem necrosis and/or gummosis, particularly in the later stage of disease 1/1/2017 13
- 14. EFFECT OF BACTERIA Enter the vascular systems, both xylem and phloem, through wounds 1/1/2017 14 Infection of Ralstonia solanacearum on tomato Infection of Xanthomonas spp. on banana
- 15. EFFECT OF FUNGI Water absorption decreases Vascular wilt diseases Decrease the water flow Polysaccharides (eg: tyloses) produced by Fusarium - obstruction of normal water translocation 1/1/2017 15
- 16. EFFECT IN TRANSLOCATIONOF WATER AND INORGANIC NUTRIENTS Root damage Damping-Off Fungi : Cause injury to roots Root-Rot Fungi, Bacteria : Inhibit root hair production Most Nematodes & Some Viruses : Alter permeability of root cells 1/1/2017 16
- 17. Cont………….. Xylem getsdestroyed Rot or Canker Pathogens Gall Formation Xylem gets clogged Growth of Vascular Wilt Pathogens Pathogen Secretions 1/1/2017 17
- 18. Effect in translocationof phloem Obligate fungal parasites Respiration increase Photosynthesis decrease Photosynthetic Products Accumulate in Invaded Areas Nutrients from Uninfected Areas are translocated toward the Infected Areas 1/1/2017 18
- 19. CONT…………… Viruses Death ofphloem Inhibit Enzymes that Break Down Starch into Smaller, Translocatable Molecules 1/1/2017 19
- 20. TRANSCRIPTION AND TRANSLATION Effecton transcription Change Composition, Structure or Function of Chromatin Associated with Cell DNA Increase in the activity of Enzymes that Break Down RNA 1/1/2017 20
- 21. Cont………… EFFECT ONTRANSLATION Higher energy needs Increased Production of Phenolics Resistant plants have high Protein synthesis in first few minutes of infection 1/1/2017 21
- 22. SUMMARY Main pathogensare bacteria, fungi and virus Pathogens mainly affect the following physiological functions in plants Photosynthesis Respiration Permeability of cell membrane Translocation of water and nutrients Transcription and translation 1/1/2017 22
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