The impact of photosynthesis on initiation of leaf senescence
Résumé
Senescence is the last stage of leaf development preceding the death of the organ, and it is important for nutrient remobilization and for feeding sink tissues. There are many reports on leaf senescence but the mechanisms initiating leaf senescence are still poorly understood. Leaf senescence is affected by many environmental factors and seems to vary in different species and even varieties of plants, which makes it difficult to generalize the mechanism. Here, we give an overview on studies reporting about alterations in the composition of the photosynthetic electron transport chain in chloroplasts during senescence. We hypothesize that alternative electron flow and related generation of the proton motive force required for ATP synthesis become increasingly important during progression of senescence. We address the generation of reactive oxygen species (ROS) in chloroplasts in the initiation of senescence, retrograde signaling from the chloroplast to the nucleus and ROS-dependent signaling associated with leaf senescence. Finally, differences between natural senescence and dark-induced senescence are 32 pointed out and a few ideas for increasing crop yields by increasing the chloroplast lifespan are presented.
Mots clés
ROS
reactive oxygen 17 species
SA
salicylic acid
SOD
superoxide dismutase
PQ
16 NAD(P)H dehydrogenase
ABA
abscisic acid
CP
chlorophyll binding protein
Cyt
cytochrome
Fd
ferredoxin
FNR
Fd- 15 NADP + reductase
JA
jasmonic acid
LHC
light-harvesting complex
PS
photosystem
NDH
plastoquinone
PTOX
plastid terminal oxidase
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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