ERGASSTIC SUBSTANCES: CLASSIFICATION AND BIOLOGICAL IMPORTANCE - BIOLOGY - 2024

The ergásticas substances are metabolic side products of plant cells and fungi. They are also called non-protoplasmic substances and can become reserve, secretory or waste substances. In general, they are not very active in the cell but sometimes they show greater biological activity.

These substances are quite diverse and some are common in plant cells, they can be organic or inorganic substances; the best known are crystals, oil drops, resins, tannins and others. They are found mainly in the vacuoles, cell wall and protoplasm.

Chemical structure of chlorophyll a, secretory ergasstic substance. In blue, white, gray, red and yellow the nitrogen, hydrogen, carbon, oxygen and magnesium atoms are appreciated respectively. Taken and edited from: ArturoSQ.

The word ergástica is an adjective that comes from the Greek ergon, which means work. According to some authors, this term began to be used in botany around 1869, however studies with bioliths (mineralized bodies produced by ergasstic substances) mention the term before the indicated date.

Classification

There is no defined or standardized scientific classification, however, some botanists agree to classify ergasstic substances into three groups: reserve, secretory, and waste.

-Ergasic reserve substances

The reserve substances or inclusions are those substances osmotically inert in the plant cell and that serve as a potential source of food (carbon and energy).

The main ergastic reserve substances are divided into three types:

Carbohydrates

Carbohydrates are the main storage substance of the plant cell. These compounds are very varied among plants, among them fructose, sucrose and glucose stand out.

Slightly more complex carbohydrates are starch, formed in chloroplasts and present in the form of grains; inulin, which is found in root tuber cells and is composed of molecular chains of fructose; and hemicellulose, which can be found on the cell walls covering cellulose fibers.

On the other hand, glycogen also acts as a reserve ergastic substance. This is a branched polysaccharide composed of glucose chains, which, although it is present in the body of animals, is generally also used as a reserve ergastic substance in fungi.

Nitrogen compounds

Nitrogen reserve compounds are complex substances from the biochemical point of view, they are generally proteins and although most are an important part of living protoplasm, they can also be found as inactive or ergasstic substances.

These substances can appear in amorphous form or in crystals. Some examples of ergasstic proteins are gluten, gliadin, and aleurone. Most of these substances are found in the vacuoles of plant seeds.

Fats and oils

Fats are excellent reserve compounds; These are widely distributed in plant tissues and appear as protective layers in or on the cell wall. When fats are liquid at ordinary or room temperature they are called oils.

Fats such as phospholipids, waxes, suberin, cutin and oil droplets are reserve ergasstic substances that are found in the form of liquid droplets in the cytoplasm, mainly in seeds and spores.

-Ergasic secretory substances

The secretory ergastic metabolites are not food substances of the cell, but they are very useful for the plant, some of them are even essential for the production of food.

Photosynthetic pigments such as chlorophyll, xanthophyll (lutein) and carotene, as well as some enzymes, for example, are secretory ergastic substances.

-Ergastic waste substances

There is an incredible amount of waste substances that plants produce. These organisms, unlike animals, do not have specialized organs for excretion, which is why they mainly deposit waste in tissues, but also have mechanisms that allow them to get rid of them.

Some ergastic waste substances are alkaloids, tannins, latex, essential oils, calcium oxalate crystals, calcium carbonate crystals, silica bodies, tartaric acid, citric acid, among others.

Some authors express that these substances do not provide any benefit to the plant. However, tannins and alkaloids, among other substances, produce a bad taste in some fruits and other structures of the plant to repel potential consumers.

Other substances can be toxic or have antifungal properties that protect the plant against attacks by these and other microorganisms.

It is also worth noting that some species of plants reuse calcium crystals and when these are found in large quantities in the tissue, they also end up being unpleasant for some herbivores, thus serving as defense mechanisms for the plant.

Human importance

Taxonomic

Botanist systematists and taxonomists use many of the ergasstic substances as a tool for classifying plants.

In particular, the shape of the crystals, the bodies of proteins, fatty alkaloids and starch, have a high value in the classification of some plants, as shown by some studies carried out with plants of the Poaceae family.

Medicinal

Ergasstic substances such as alkaloids are extracted as bioactives from plants and are frequently used for the production of medicines. Quinine is an example of a waste ergastic substance that has antimalarial, antipyretic, and analgesic properties. Morphine is also another example of these substances.

Model of the morphine molecule, ergasstic waste substance. Taken and edited from: RedAndr.

Industrial

Ergasstic substances have a high value in the industry. They are used directly through extraction by chemical methods, or indirectly using part of the plant tissue for consumption in the form of infusions for example.

Caffeine and nicotine are two well-known examples of alkaloids that are ergasstic substances used in the coffee and tobacco industry. Both are among the most industrially profitable plant-based substances in the world today.

Tannins are also ergasstic substances used industrially. From these metabolites dyes are produced, they are also used in the curing process of skins (hides) and are very important in the production of wines.

The food industry uses reserve substances from plants, such as sugars, which are extracted from species such as beets and sugar cane, while fats are used for the production of glycerin and soaps for commercial purposes.

References

1. M. Gupta. Ergastic substances present in the cells of a plant - botany. Recovered from: biologydiscussion.com.
2. The vegetal vacuole and ergasstic substances. Recovered from: euita.upv.es.
3. T. Tatteoka (1955). Further studies in starch grains of seeds in Poaceae from the view points of systematics. Japanese Journal of Botany.
4. M. Idu & HI Onyibe (2008). Nature of ergastic substances in some Fabaceae seeds. Research Journal of Botany.
5. Ergastic substances or inclusions. Recovered from: docencia.udea.edu.co.
6. Ergastic substance. Recovered from: revolvy.com.