What is Sporopollenin?
Sporopollenin is an outer thick layer found on the surface of plant spores and pollen grains. It is a lipid and phenolic-based polymer. It is one of the most chemically inert biological polymers known. It is also found in several algal species.
The inertness of the sporopollenin gives the pollen grains and spores to persist in soil sediments for millions of years. This gives an advantage to the scientist to recognise the plants based on their surface and structure.
The sporopollenin is synthesised by the lipophilic globules present in the tapetal cells that are believed to have sporopollenin precursors. The major function of sporopollenin is to provide protection against tough environments.
What is Cuticle?
A plant cuticle is an outer layer that covers the epidermis of all the aerial parts of a plant. It is composed of cutin and a variety of organic solvent soluble lipids. It is synthesised by the epidermal cells.
The waxes on the cuticle are either deposited within the cuticle, referred to as intracuticular wax or get accumulated on the cuticular surface, referred to as epicuticular wax. The surface accumulation of the wax gives a shiny and glossy appearance as can be seen in fruits like apples and cherries. The deposited wax inside the cuticle gives a dull, glaucous appearance as can be seen in a rose flower.
The major function of a cuticle layer is to prevent the loss of water from the stomatal surface. It acts as a barrier to the epidermal cells to prevent contamination from outer dirt, microbes and water. The plants have a thick cuticle layer on their top surface as compared to the lower surface to prevent loss of water through evaporation. However, in xerophytic plants, the cuticle is present in equal amounts on both sides of the leaves to minimise water loss.
Sporopollenin vs Cuticle
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Sporopollenin |
Cuticle |
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Description |
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An outer tough layer found on the surface of spores and pollen grains is referred to as sporopollenin. |
A glossy layer present on the aerial parts of a plant is referred to as cuticle. |
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Composition |
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It is composed of long fatty acid chains, phenolics, phenylpropanoids and traces of carotenoids. |
It is composed of cutin interspersed with a variety of waxes. |
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Chemical Nature |
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It is a lipid and phenolic based polymer. |
It is a continuous lipophilic layer. |
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Secreted By |
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It is secreted by the tapetal cells. |
It is secreted by the epidermal cells. |
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Location |
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It is found on the surface of pollen grains and spores. |
It is found on all primary organs or aerial parts of a plant. |
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Function |
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It provides a tough exterior to the pollen and spores to protect them from the harsh environments. |
It prevents extra loss of water from the epidermal and stomatal surfaces. |
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Also Read:
- Difference Between Epidermis and Dermis
- Transpiration in Plants-Types, Factors and Significance
- What is the difference between cuticle and chitin?
Frequently Asked Questions
What is sporopollenin made of?
Sporopollenin is a highly inert cross linked polymer that is made up of long-chain fatty acids, phenylpropanoids, phenolics and traces of carotenoids in a random co-polymer.
Do gymnosperms have cuticles?
Yes, gymnosperms have a thick cuticle on the leaf surface to prevent water loss.
What can degrade sporopollenin?
After pollination, the intine releases a mixture of enzymes that degrades the sporopollenin.
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