Table of Contents
Effect of pathogens on plants
What is Pathogen?
- A pathogen or infectious agent is a biological agent that causes disease or illness to its host.
- The term is most often used for the agent that disturb the normal physiology.
- The main pathogen are the virus, bacteria, and fungi.
The physiological function includes:
- Pathogenesis
- Respiration
- Permeability of cell membrane
- Translocation of water and nutrient
- Transcription and translation
Pathogenesis
- Pathogenesis is a basic function of plant
- It transforms light energy into chemical energy which is utilized by cellular activities
- Any pathogen that interferes with it will cause disease that may appear as chlorosis (yellowing) and necrosis (burring and death) of leaves and stem.
- Reduce the amount of photosynthesis surface.
Image Source: https://doi.org/10.1016/j.pbi.2016.06.012
Effect of virus infection
- Reduce chloroplast amount
- Reduce chlorophyll and sucrose amount
- Cause chloroplast abnormalities.
Effect of bacterial infection
- Decrease in chloroplast
- Suppress CO2 fixation
Effect of fungal infection
- Reduce chloroplast content
- Loss of chlorophyll
- Reduce photophosphorylation coupling mechanism
- Suppress CO2 fixation
Respiration
- Respiration increase during pathogen attack
- Rate continuous to rise during multiplication and sporulation of the pathogen
- Decline to normal or below the normal level
- Increased respiration decrease in plant reserve
- Change metabolism
Effect of virus
- Slightly increase respiration rate in leaves
Effect of fungi
- Respiration rate is usually increased in diseased plants.
- In the early stage of disease synthetic process-induced high rate of respiration.
- In late-stage, injury and decomposition lead to increase respiration.
Mechanism of permeability
Pathogen change the permeability by
- Mechanical injury
- Enzymatic degradation
- Toxins
- Cause leakage of electrolytes.
Translocation water and nutrient
- Affect the function of root
- Roots absorb less water
- Interfere with water economy of plant by causing excessive transpiration.
Effect of bacteria
- Enter the vascular system in both xylem and phloem through the wound
Effect of fungi
- Decrease water absorption
- Vascular Wilt disease
- Decrease water flow
Effect of virus
- Death of phloem
- Inhibit enzymes that break down starch into smaller into translatable molecules.
Transcription and Translation
- Disturbance in any of above both process may effect the following
- Expression of genes
- Cause a drastic unfavorable change in the structure and function of affected cells.
References
- https://www.cram.com/flashcards/effects-of-plant-pathogens-on-plant-physiological-functions-401789
- http://www.davidmoore.org.uk/21st_Century_Guidebook_to_Fungi_PLATINUM/Ch14_11.htm
- https://academic.oup.com/jxb/article/58/15-16/4019/454268
- https://www.ncbi.nlm.nih.gov/pubmed/18182420.