title: Carotenoid oxidation products are stress signals that mediate gene responses to singlet oxygen in plants.
abstract: (1)O(2) (singlet oxygen) is a reactive O(2) species produced from triplet excited chlorophylls in the chloroplasts, especially when plants are exposed to excess light energy. Similarly to other active O(2) species, (1)O(2) has a dual effect: It is toxic, causing oxidation of biomolecules, and it can act as a signal molecule that leads to cell death or to acclimation. Carotenoids are considered to be the main (1)O(2) quenchers in chloroplasts, and we show here that light stress induces the oxidation of the carotenoid β-carotene in Arabidopsis plants, leading to the accumulation of different volatile derivatives. One such compound, β-cyclocitral, was found to induce changes in the expression of a large set of genes that have been identified as (1)O(2) responsive genes. In contrast, β-cyclocitral had little effect on the expression of H(2)O(2) gene markers. β-Cyclocitral-induced reprogramming of gene expression was associated with an increased tolerance to photooxidative stress. The results indicate that β-cyclocitral is a stress signal produced in high light that is able to induce defense mechanisms and represents a likely messenger involved in the (1)O(2) signaling pathway in plants.
authors.affiliation: Commissariat à l'Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Environnementale et Biotechnologie,  Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance,  France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Ramel
authors.forename: Simona
authors.initials: S
authors.lastname: Birtic
authors.forename: Christian
authors.initials: C
authors.lastname: Ginies
authors.forename: Ludivine
authors.initials: L
authors.lastname: Soubigou-Taconnat
authors.forename: Christian
authors.initials: C
authors.lastname: Triantaphylidès
authors.forename: Michel
authors.initials: M
authors.lastname: Havaux
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism*; D015870:Gene Expression; D005819:Genetic Markers; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D026082:Singlet Oxygen / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D005819:Genetic Markers; D026082:Singlet Oxygen; D002338:Carotenoids; D006861:Hydrogen Peroxide