plant pathogen detection, diagnosis

4.  The traditional method of identifying plant pathogens is
through visual examination.
 This is often possible only after major damage has already
been done to the crop, so treatments will be of limited or
no use.
 To save plants from irreparable damage by pathogens,
farmers have to be able to identify an infection even before
it becomes visible.
This can be reached by using very sensitive methods for early
diagnosis of disease

5. diagnosis of plant disease is to identify the disease
nature and To determine the causal agent
whether living or non living
Diagnosis Of Plant Disease

6. The symptoms which appear on plants may be
because of
Biotic factors
A biotic factors

7. field
laboratory
1- Become acquainted with the environmental Conditions
surrounding the plant
2- Review of agricultural operations
3- examination Of the plant sample
1- Soil analysis and measurement of pH
2- hypothesis Koch
3- Biochemical methods
4- microscopic examination
5- serological methods
6- the use of methods rely on DNA
The methods used to identify the symptoms are:

8. These symptoms may be diagnostic or non-diagnostic
Diagnostic Non Diagnostic

9. The filed methods can be used to identify the morphological
:symptoms Which may be
Local symptoms Systemic symptoms

11. As mentioned before , the laboratory
methods are :
1- Soil analysis
2- Koch's postulates
3- Biochemical methods
4- Microscopic examination
5- Immunological methods
6- The use of methods rely on DNA

12. Direct visualization of
Entire genomes
Restriction digestion
And electrophoresis
Of DNA
The polymerase
Chain reaction
(PCR)
Hybridization of
DNA and RNA
Nucleic acid techniques included :

13. 1-DNA extraction
2-PCR amplification
3-Gel Electrophoresis and analysis

14. DNA extraction

15. PCR amplification

16. Gel Electrophoresis and analysis

17. Selection of target DNA to
amplify

18. The gene segment of eukaryotic rDNA contains 18S, 5.8S, and 28S tracts and
forms a tandem repetitive cluster; the 5S rDNA is coded separately. NTS,
transcribedinternal,ITSspacer,transcribedexternal,ETSspacer,nontranscribed
.end'5fromnumbered,2and1spacers

20. Identification of Bacteria Using 16SrRNA
Sequancing
1500 bp
120 bp2900 bp

25. Summary
The use of the most sensitive and modern methods helps a lot in early
identification of disease
These modern technologies include PCR beside serological methods
And through which , access to the real cause of the disease in a short time is
possible before significant losses in yield are encountered