Nonenzymic carotenoid oxidation and photooxidative stress signalling in plants.
Carotenoids play a crucial protective role in photosynthetic organisms as quenchers of singlet oxygen ((1)O(2)). This function occurs either via a physical mechanism involving thermal energy dissipation or via a chemical mechanism involving direct oxidation of the carotenoid molecule. The latter mechanism can produce a variety of aldehydic or ketonic cleavage products containing a reactive carbonyl group. One such molecule, the volatile β-carotene derivative β-cyclocitral, triggers changes in the expression of (1)O(2)-responsive genes and leads to an enhancement of photooxidative stress tolerance. Thus, besides their well-known functions in light harvesting and photoprotection, carotenoids can also play a role through their nonenzymic oxidation in the sensing and signalling of reactive oxygen species and photooxidative stress in photosynthetic organisms. Enzymic carotenoid oxidation does not seem to play a significant role in this phenomenon. Elucidation of the carotenoid-mediated (1)O(2) signalling pathway could provide new targets for improving photooxidative stress tolerance of plants.
CEA, DSV, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.
Fanny
F
Ramel
Alexis S
AS
Mialoundama
Michel
M
Havaux
D002338:Carotenoids / Q000378:metabolism*; D018384:Oxidative Stress / Q000528:radiation effects; D010788:Photosynthesis; D010944:Plants / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D015398:Signal Transduction / Q000528:radiation effects
D002338:Carotenoids