Redox functions of carotenoids in photosynthesis.
Importance of Pigments in Photosynthesis | Sciencing
Plant pigments are important cues to humans and other herbivorous animals in helpingidentify plants, find plant parts such as fruit, leaves, stems, roots, or tubers, anddetermine stages of plant development such as fruit ripeness or overall senescence. It wasrealized early in this century that many of these pigments play a positive role in humanhealth. In 1919, Steenbock noted that yellow corn ( L.) and"yellow" vegetables (carrots ( L.) and sweetpotato ( L.)) eliminated the symptoms of vitamin A deficiency in rats while white cornand "white" vegetables (parsnip ( L.), potato ( L.), and beets ( L.) did not (; ). Since then, approximately 40 carotenoids have been found to bevitamin A precursors (). When provitamin Acarotenoids are consumed, they are enzymatically broken down to retinol (vitamin A). Inthis way, consumption of horticultural crops provides over 80% of the vitamin A for theworld (). Vitamin A deficiency worldwide isthe most common specific dietary deficiency as it afflicts millions of children each yearwith xerophthalmia, blindness, or death. Subclinical deficiency also reduces immunefunction to increase the risk of severe and fatal infections (). Therefore, the development of new andmore potent sources of provitamin A carotenoids in horticultural crops, and improvement ofproduction, shelf life and consumer acceptance of these crops can make an importantcontribution to improved human health.
Carotenoid pigments are found in many photosynthetic organisms, ..
Very soon after, more pieces of the puzzle were found by two chemists working in Geneva. Jean Senebier, a swiss pastor, found that "fixed air" (CO2) was taken up during photosynthesis, and Theodore de Saussure discovered that the other reactant necessary was water. The final contribution to the story came from a German surgeon, Julius Robert Mayer (right), who recognised that plants convert solar energy into chemical energy. He said: