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The below mentioned article provides a practical experiment on the Isolation of Plant Pathogen.
Principle:
The term ‘pathogen’ means the organism that incites diseases on living being. It may be fungus, bacteria, virus etc. The pathogen can easily be isolated in artificial culture media for identification and subsequent characterisation.
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Requirements:
1. Infected plant parts/plant
2. Petridishes
3. Forceps and knife
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4. Mercuric chloride solution (1:1000)
5. Distilled water (steriled)
6. Slants with desirable culture media
7. Incubator
8. Bunsen burner
9. Slide and cover glass
10. Microscope
11. Absolute alcohol
Procedure:
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(1) An infected plant or leaf of rice was brought to the laboratory from the field for isolation of pathogen.
(2) Initially the symptoms were examined under microscope or by hand lens. The infected lesionic part was removed by a knife and quickly transferred to the sterilising solution.
(3) Surface sterilisation of the infected plant was done by transferring the excised infected leaf segment into a petridish containing mercuric chloride solution (1: 1000) and kept for 2 – 3 min.
(4) Then the leaf segment was transferred to a series of petridishes containing sterile distilled water for washing of mercuric chloride.
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(5) Finally the excised leaf segment was placed aseptically into the slant for culture of pathogen.
(6) The slant was then incubated at a required temperature for 3 – 5 days after proper leveling.
(7) Finally, the culture thus developed was examined microscopically.
Observation:
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On microscopic examination of culture, conidia of Helminthosporium with conidiophores were noticed.
The detailed steps of isolation of pathogen are presented in the Fig 3.36.
