The document discusses two types of plant disease resistance: vertical and horizontal. Vertical resistance is conferred by single genes and results in complete but specific resistance. Horizontal resistance is conferred by multiple genes and results in partial but non-specific resistance. The document also notes that disease is usually specific to a pathogen while resistance tends to be less specific. It provides pros and cons of each type of resistance and current strategies that use horizontal resistance.

1. In 1963 : Van Der Plank wrote a book
named “ Plant Diseases: Epidemics and
Control ’’
Resistance to Plant Diseases

2. Concepts:
Vertical & Horizontal Resistance
 Disease is specific and Resistance is
unspecific

3. True Resistance
Vertical Resistance Horizontal Resistance

4. Vertical resistance: The resistance due
presence of single gene is called vertical resistance
Features:
1. Complete resistance
2. Specific resistance
3. Monogenic
Qualitative Resistance

5. Resistant Gene
Resistance
100%
V1

6. R1
Resistant Gene
Resistance
100%
V1

7. R1
Resistant Gene
Resistance
100%
V1 V2

8. R1 R2 R3
Resistant Gene
Resistance
100%
V1 V2 V3

9. Pros & Cons
 Complete Resistance to Complete
Failure
 Help to create to eliminate pathogen
but promote highly mutated strains
 Farmers choice but pathologists
nightmare

10. Horizontal Resistance
The resistance due presence of more than one
gene.
Features
I. Never give complete resistance rather partial
resistance
II. Multigenic
III. Non-specific
Quantitative Resistance

11. 100 %
Resistant Gene
Resistance
R1
R2
R3
Horizontal Ressiatnce

12. Pros & Cons
 Incomplete Resistance to Incomplete
Failure
 Never eliminate pathogen but live &
let live
 Pathologists choice but farmers not
like it

13. 100 %
Resistant Gene
Resistance
R1
R2
V3
Current Strategy

14. Disease is specific and Resistance is
unspecific

15. Disease is specific

16. Resistance is unspecific
Disease is specific and Resistance is
unspecific

17. https://pathologyforum.blogspot.com/2020/03/vertical-vs-
horizontal-resistance.html
https://pathologyforum.blogspot.com/2020/03/disease-is-
specific-resistance-is.html
https://www.youtube.com/watch?v=MYs8NdRMDco&t=7s