Question

Name important defence mechanisms in plants against herbivory.

Answer 1

Hint: The pathogens are agents which cause disease. These agents are infectious in nature, like bacteria, fungi and helminths, which live as a parasite on the plant causing damage to the tissues. Plants have numerous strategies developed to encounter them.

Complete answer:
Plants provide defenses against herbivory in morphological and chemical terms. Any morphological defenses include the modification of leaves into spines, the appearance of sharp thorns and spiny leaf margins. Mechanisms of chemical protection include the plant development of phytoalexins and constitutive compounds. This is the secondary chemical compounds that act as toxins/disrupt the metabolism or normal larval growth or decrease the plant's digestibility. Mustard oil from mustard plants, for example, and milky sap from milkweed plants.

1.To defend them from herbivores, many plants have impenetrable defenses, such as bark and waxy cuticles, or adaptations, such as thorns and spines.
2.If herbivores penetrate the barriers of a plant, the plant may react with secondary metabolites that are often toxic compounds that can damage the herbivore, such as glycol cyanide.
3.Damaged plant tissue releases jasmonate hormones when attacked by a predator, which facilitate the release of volatile compounds, ultimately killing the pathogen.

Note: In the compromised tissue, mechanical wounding and predator attacks trigger protection and protective mechanisms and elicit long-distance signalling or triggering of defense and protective mechanisms at places further away from the place of injury. Within minutes, some defensive reactions occur, while others can take several hours.