Like Animals, Plants also have aimmune system. Every cell in a plant has the ability to detect and defend itself against pathogens.
--> Plants have their own unique physical and chemical defense mechanisms to protect themselves against a variety of pathogens.
The first line of defense in plants is an external impenetrable barrier. This barrier consists of bark and a waxy cuticle. Other mechanical barriers include hard shells, thorns and spines. All these physical adaptations protect plants against foreign invaders.
If these external defenses are breached, plants trigger their internal immune system.
Plants have special cell-surface receptors to identify pathogens. Such receptors, when activated, trigger an immune response within the cell to prevent pathogens from entering the plant. Plants increase the thickness of their waxy cuticle and its cell wall gets stronger.
If microbes succeed in damaging one section of the plant. It will send signals to self-destruct cells in a localized area around the site of infection to restrict the growth and spread of pathogens to other parts of the plant.
An area of a plant under attack can alert other regions using hormones, airborne compounds or even electrical signals. When other parts of the plants detect these signals they increase their production of defensive compounds.
--> Some plants form beneficial relationships with other organisms that protect them from other harmful pathogens. In fact, when some plants are being eaten by caterpillars. They send chemical signals to parasitic wasps who come to the rescue and attack the caterpillars.
--> Plants produce compounds that are toxic to microbes and insects. Often these compounds are tailor-made for a specific threat.
--> A stinging tree called the Gympie Gympie produces a toxin so painful that it has driven people and animals to suicide.
--> The plants' immune system is complicated. More studies are needed to better understand their protective mechanisms.
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