Horizontal and Vertical resistance in plants are the opposing force or blocking force that protects the plants from the attack of different pathogens.
Different plants has thier own ability to fight against pathogenic attack. These plants are called resistant plants while Some plants are highly resistant and some are easily attacked by pathogens. Such plants are called susceptible.
The resistance in plants is done by some kind of genes say:- R-gene. These genes code for specific material in response to certain pathogenic attack.
Based on the presence of type of resistance gene -There are 2 types of resistance i.e Horizontal And Vertical Resistance in plant pathology. They are discussed below. So- Read the Post till end.
Resistance In Plants
The two type of resistance in plant are:-
1.Horizontal Resistance In Plant
2.Vertical Resistance In Plant
Before we directly jump into detailed overview of these two types of plant resistance. Lets, have a look on the difference between horizontal and vertical resistance in plants. There are total 7 differences which are listed and explained below:-
|Features||Horizontal resistance||vertical resistance|
|1.Other Names||Partial Resistance, Polygenic Resistance, Gene non – specific Resistance, field resistanc||Qualitative resistance, R-resistance, Monogenic resistance, gene-specific resistance,|
|2.Nature Of Gene Action||Polygenic||Monogenic/oligogenic|
|4.Efficiency||Against all races||Against specific races|
|6.Stage Of Expression||Increases with maturity||Same from seedling to maturity|
|7.Chance Of Epidemic||Less/Minimal||Present|
Now – We will be discussing all these characteristics of horizontal and vertical resistance in plant in detail:-
1.Nature Of Gene Action
➡️Horizontal resistance in plant is polygenic that means-It has many genes that can resistant against different virulent genes.It is specific.
➡️Vertical resistance is monogenic and sometimes oligogenic that means-It shows action against certain specific gene only.Its like gene for gene.
Pathotype is group of individuals that attacks some specific host. Some group attack one host while other group attack another host.
➡️Horizontal resistance is non-specific that means- It works against all kinds of pathogen. The resistance mechanism activates in every group of pathogen that attacks the plant.
➡️Vertical resistance is specific that means-It works against specific pathotype. This resistance mechanism works for specific group but don’t work for another group of pathogen.
➡️Horizontal resistance in plant shows efficiency among all the races of pathogen. It works against all pathogens but cannot fully defend them. They slows down the damage caused by pathogens.
➡️Vertical resistance in plants shows action against specific race of pathogen. The effectiveness they show is very strong. They completely destroy the pathogens and saves the plants.
➡️Horizontal resistance is very effective against necrotrophs. This is because necrotrophs are the pathogens that kills the host tissue in advance of penetration. Thus-Horizontal resistance shows its mechanism when the pathogens are trying to kill the host tissue.
➡️Vertical resistance is very effective against biotrophs. This is because biotrophs are the pathogens that cannot live outside of living cells. In vertical resistance-There is a thing called Hypersensitivity. Due to this Hypersensitivity-When pathogen attacks plant vertical resistance cause the necrosis of its own plant cell. As the area attacked by pathogens undergo necrosis. That part becomes dead and biotrophs can’t live outside living cell. That’s why vertical resistance is effective against biotrophs.
5.Stage Of Expression
➡️Horizontal resistance in plants increases as the plant goes on maturing. This is durable form of resistance.
➡️Vertical resistance in plants is expressed from seedling to maturity in same power. It is less durable.
6.Chance Of Epidemic
➡️Horizontal resistance acts against all the races. That is why any changes or mutation in the race of plant doesn’t affect the plants. There is minimal risk of inflection.There is no chance of epidemic.
➡️Vertical resistance acts only on certain group of specific race of pathogen. Any changes within the pathogen or any attack by new pathogen completely destroy the plant. There is a chance of epidemic.
Example Of Horizontal And Vertical Resistance In Plant
Let us consider the 5 types of pathogen races.
The first bar diagram explains:- Vertical resistance is shown against the races 2,5 and 6. The resistance shown is complete that means the plants do not loss any production. They are completely healthy. Remaining races become completely susceptible.
The second bar diagram explains:- Horizontal Resistance acts against all the races. But-They can’t completely oppose the races. They are mimizing the damage caused by pathogens. That’s why the bar diagram is light green and height is half.