noun, plural: carotenes
Accessory pigments are non-chlorophyll pigments within the chloroplasts of photoautotrophs. They help in absorbing other light energy essential during the light reactions of photosynthesis. There are two major types of accessory pigments in plants and they are carotenoids and phycobilins. Carotenoids are accessory pigments that are typically yellow, red and orange. They are insoluble in water in contrast to phycobilins that are water-soluble. They occur in chloroplasts where they aid in the light absorption for photosynthesis. They are also found in chromoplasts. There are various carotenoids and they are grouped into xanthophylls and carotenes.
Carotenes are carotenoid pigments that are oxygen-free. Most of them are hydrocarbons, i.e. containing only carbon and hydrogen, and belong to the unsaturated hydrocarbons. Their color varies from yellow to orange to red. The color is attributed to the chain of alternating single and double bonds. Carotenes are naturally synthesized by plants but not by animals, except for certain species of aphids and spider mites.1
α-carotene, β-carotene, and lycopene are examples of carotenes. They are important in photosynthesis since they are able to absorb UV, violet and blue light.
1 Altincicek, B., Kovacs, J. L., & Gerardo, N. M. (2011). "Horizontally transferred fungal carotenoid genes in the two-spotted spider mite Tetranychus urticae". Biology Letters 8 (2): 253–257.