Role in Plants

In the process of photosynthesis, potentially harmful oxidizing compounds are generated. The carotenoids occur in photosynthetic tissues along with chlorophyll to protect them from photooxidative damage. In fact, this protection is essential for photosynthesis. The photoprotective role of carotenoids is demonstrated in plant mutants that cannot synthesize essential leaf carotenoids. These mutants are lethal in nature since without carotenoids, chlorophylls degrade, their leaves are white in color, and photosynthesis cannot occur. Carotenoids also assist chlorophylls in harvesting light. Carotenoids absorb wavelengths of blue light that chlorophylls do not. The energy that carotenoids harvest in the blue range of the spectrum and transfer to chlorophyll contributes significantly to photosynthesis. The growth and development of plants is often stimulated by light, and

compound a substance formed from two or more elements photooxidize to react with oxygen under the influence of sunlight

A carrot harvest. Carrots contain at least six different carotenes that account for their color.

Genetic engineering of rice may allow high expression of carotenoids. However, the normally white rice becomes yellow-orange in the process, which may not be appealing to consumers.

carotenoids have sometimes been implicated as the photoreceptors of light to trigger these responses.

Outside of photosynthesis, plant carotenoids also serve as one of the pigments, along with anthocyanins and betalains, that provide color to flowers, ripening fruit, and other plant parts. Familiar examples of carotenoids having this role are found in sunflowers, marigolds, bananas, peaches, oranges, tomatoes, peppers, melons, and yellow corn. Two root crops, carrots and sweet potatoes, also acquire their color from carotenoids. These colors attract insects, birds, and bats for pollinating flowers, and they attract a wide range of animals to aid in the dispersal of seeds and fruits.

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