Examples of chemical plant defences include alkaloids, tannins, and secondary metabolites such as salicylic acid and jasmonic acid. These compounds can have toxic effects on disease-causing agents and help to boost the plant's overall immunity.
Chemical Defenses. Plant chemicals can be divided into two major categories: primary metabolites and secondary metabolites. Primary metabolites are substances produced by all plant cells that are directly involved in growth, development, or reproduction. Examples include sugars, proteins, amino acids, and nucleic acids ...
Plants are constantly defending themselves from attack from pathogens and from animals that want to eat them called herbivores . They have therefore developed physical and chemical defences, which stop them from being eaten, and pathogens from infecting them and causing disease.
Other defense chemicals include enzymes and products, which are harmful to invading organisms. For example, proteinase inhibitors (PINs) in potato or tomato shoots, when ingested by the insect, inhibit the protein-digesting enzymes, trypsin and chymotrypsin, in the insect gut.
Plants, as a whole, are well stocked with chemical defense compounds that function in protection against herbivores and pathogens. Within individual plants, however, there is extensive variation in the amounts of chemical defenses among different organs, tissues, and developmental stages.
Many plants have an inbuilt defence system that, when activated, releases hydrogen cyanide to ward off insects and fungi. It is directed at the part of the plant under attack. This is what makes bitter almonds, apricots, and apple pips toxic when crushed.
Chemical defences
Some plants, like stinging nettles and foxgloves, have developed poisons to deter herbivores from eating them. They produce these constantly.
Chemical defenses : Formed by chemical compounds stored, like phenolics, terpenoids, and alkaloids, and released under attack. Antinutritive defenses include chemical, toxins, defensive proteins, enzymes, and resin deposits that can flow to repel or physically trap small organisms.
The human body has three primary lines of defense to fight against foreign invaders, including viruses, bacteria, and fungi. The immune system's three lines of defense include physical and chemical barriers, non-specific innate responses, and specific adaptive responses.
Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.
The first line of defense in plants is an intact and impenetrable barrier composed of bark and a waxy cuticle. Both protect plants against herbivores. Other adaptations against herbivores include hard shells, thorns (modified branches), and spines (modified leaves).
Structural defenses. Once herbivores find and access a plant, structural defenses can discourage consumption. These structures include spinescence, trichomes, thick leaves, and microscopic sand- and needle-like particles inside plant tissues (Figures 3 and 4).
“Vegetables contain TOXIC compounds!” Based on idea that compounds like lectins, saponins, phytate, and oxalates are all defense mechanisms to dissuade animals from eating them.
Chemical defense is a strategy employed by many organisms to avoid consumption by producing toxic or repellent metabolites or chemical warnings which incite defensive behavioral changes. The production of defensive chemicals occurs in plants, fungi, and bacteria, as well as invertebrate and vertebrate animals.
1 Answer. there are few chemicals which plants uses to mount a defense response, examples include phenolic groups, terpenoids and alkaloids.
The most commonly recognized of these defenses are self-defense and defense of others. A defendant may argue, for instance, that he did shoot an intruder but did so in self-defense because the intruder was threatening him with a knife.
Glandular trichomes secrete secondary metabolites including flavonoids, terpenoids, and alkaloids that can be poisonous, repellent, or trap insects and other organisms, thus forming a combination of structural and chemical defense. Induction of trichomes in response to insect damage has been reported in many plants.
Traditionally, plant defenses have been divided into two main categories: chemical and mechanical defenses. The first category includes a variety of substances that are toxic, repellent, or that render plant tissues indigestible to animals.
Though it may seem strange, the purpose of caffeine is not to stimulate the human nervous system (though it is a wonderful side effect) but rather it is produced as a defense mechanism for the plant. Making this compound is a complex process that involves many metabolic steps within the tissues of the plant.
Nicotiana tabacum synthesizes a toxic alkaloid, nicotine, in its belowground organs and rapidly translocates it to aboveground parts in response to herbivory. The inducible nicotine can protect the plants against generalist herbivores (Baldwin, 1988).
The characteristic flavor of cauliflower, typical for other cruciferous vegetables, is related to the presence of sulfur compounds and their derivatives. These sulfur compounds are named glucosinolates (GLS) which are plant defensive metabolites found in all other Brassica plants.
Some, like tomato plants, release chemicals like methyl jasmonate that not only taste bad to pests, but alert their leafy neighbors to trouble.