Biological Pigments in Plants: Definition, Types and Examples

What Are Pigments?

In simple terms, these are any of the naturally occurring compounds that absorb and reflect wavelengths of light to give colour and make different physiological functions within living organisms possible. The pigments play a fundamental role in photosynthesis in plants by capturing the energy from light and then storing it in the form of chemical energy.

The paper discusses different types of biological pigments, such as chlorophylls, carotenoids, and phycobilins, in connection to their role in the health functions of plant pigment. Their contribution to the effectiveness of photosynthesis via absorption and photoprotection shall also be discussed.

Types Of Biological Pigments

The green chromophores compose the general category of chlorophylls whose basic structure includes a porphyrin ring bound to the central magnesium ion.

Chlorophyll

The details for chlorophyll are given below:

Structure and Types

The most widely distributed forms are chlorophyll a, which plays a part in electron transfer during the realisation of light-dependent reactions in photosynthesis, and chlorophyll b, which captures light energy and extends the spectrum of absorbed light. Such forms as chlorophyll c, d, and e are well spread in certain algae. Their function is the same as in the above cases, only adapted to some other light conditions.

Role in Photosynthesis

Chlorophylls absorb light energy emanating from the blue-violet and red ends of the visible spectrum and convert light energy into chemical energy. The chemically converted form of light energy gets stored and put to use again in the synthesis of glucose from carbon dioxide and water.

Distribution in Plant Cells

Chlorophylls are found in plant cells. In plant cells, they are mainly distributed in the chloroplasts and more clearly in the thylakoid of the chloroplast where light reactions take place.

Carotenoids

The details for carotenoids are given below:

Types

There are two types of carotenoids. They are carotenes( ex; β-carotene ), and xanthophylls( ex; lutein ).

Role in Photosynthesis and Photoprotection

They absorb bluish-green light, which is not absorbable by chlorophyll itself, and then transfer the energy to the chlorophyll. Also, they serve to protect the photosynthetic apparatus from too much harmful light energy by scavenging it and dissipating it as heat.

Examples (β-Carotene, Lutein)

One such carotenoid is beta-carotene, which is a naturally occurring precursor to vitamin A, important in nutrition. Another is lutein, which protects the tissue of the plant from light damage.

Anthocyanins

The details for anthocyanins are given below:

Chemical Structure and Variability

The anthocyanins are a water-soluble group of pigments having the general structure of a glycosylated flavonoid. It underlies the colour in the red, purple, and blue colours in plants. Herein, the precise chemical structure of the individual anthocyanins and also its specific glycosylation pattern are variable.

Role in Plant Defense and Attraction

The colours of anthocyanins are bright, playing a double role in defending the plant against herbivores and again attracting pollinators.

Distribution in Plant Tissues

They occur in different tissues of the plants like fruits, flowers, and leaves. Being part of the pigment system, they colour the plants and interact with the environment.

Other Pigments

The other pigments are described below:

Flavonoids

These are pigments implicated in plant pigmentation, UV protection, and signalling. The subtypes, such as flavonols and flavones, are implicated in the defence mechanisms of the plant and in attracting pollinators.

Phytochromes

Light receptor pigments control the response of plants to the presence or absence of light. This response includes seed germination and time of flowering.

Cryptochromes

Another pigment, which acts as a receptor of blue light. It is controlling growth and developmental processes in response to changes in light.

Role and Distribution in Plants

The pigments are differentially distributed in plant tissues and result in differential functioning concerning light perception, development, and protection against environmental stresses.

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