The impact of photosynthesis on initiation of leaf senescence

Abstract

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, a few ideas for increasing crop yields by increasing the chloroplast lifespan are presented.

Manganese Repairs the Oxygen-Evolving Complex (OEC) in Maize (Zea mays L.) Damage During Seawater Vulnerability

“…Photosynthetic apparatus comprises a number of pigments/protein complexes viz., photosystem (PSII), cytochrome b6f (Cytb 6 f), and photosystem I (PSI) situated in the thylakoid membrane of the chloroplast. Light energy captured by light-harvesting systems of PSII and PSI is transferred to reaction center chlorophyll, where charge separation occurs, and electron transport is initiated (Krieger-Liszkay et al 2019). On the donor side of PSII, the oxygenevolving complex (OEC) breaks the water molecules and releases both electrons and molecular oxygen (Yanykin et al 2010).…”

iTRAQ-based quantitative proteomic of tobacco (Nicotiana tabacum L.) identified major host proteins involved in photosystems throughout the aging process

“…We identified 126 proteins (34 proteins were up-regulated and 92 proteins were down-regulated) that belong to "metabolic pathways", 64 proteins (28 proteins were upregulated and 36 proteins were down-regulated) that belong to "Biosynthesis of secondary metabolites", 37 proteins (8 proteins were up-regulated and 29 proteins were down-regulated) that belong to "Microbial metabolism in diverse environment", 19 proteins (8 proteins were up-regulated and 11 proteins were down-regulated) that belong to "Starch and sucrose metabolism". Up-regulated proteins were also involved in "Phenylpropanoid biosynthesis" (8), "Tyrosine metabolism" (8), "Phenylalanine metabolism" (7), "Isoquinoline alkaloid biosynthesis" (6), "Splicer" (6) and "Protein processing in endoplasmic reticulum" (9), which were different from the functional metabolic pathways of down-regulated proteins. Down-regulated proteins were involved in metabolic pathways, including "Photosynthesis" (25), "Carbon fixation in photosynthetic organisms" (13), "Glycolysis/glycogenesis" (9), "Pentose phosphate pathway" (8), "Glutathione metabolism" (7) and "Oxidative phosphorylation" (7) and so on ( Fig.…”

“…Simultaneously, large molecules such as proteins and nucleic acids are degraded, which causes a decline in photosynthesis during leaf senescence. Therefore, leaf senescence has an important effect on photosynthesis [5,6].…”

iTRAQ-based quantitative proteomic of tobacco (Nicotiana tabacum L.) identified major host proteins involved in photosystems throughout the aging process

“…We identified 126 proteins (34 proteins were up-regulated and 92 proteins were down-regulated) that belong to "metabolic pathways", 64 proteins (28 proteins were upregulated and 36 proteins were down-regulated) that belong to "Biosynthesis of secondary metabolites", 37 proteins (8 proteins were up-regulated and 29 proteins were down-regulated) that belong to "Microbial metabolism in diverse environment", 19 proteins (8 proteins were up-regulated and 11 proteins were down-regulated) that belong to "Starch and sucrose metabolism". Up-regulated proteins were also involved in "Phenylpropanoid biosynthesis" (8), "Tyrosine metabolism" (8), "Phenylalanine metabolism" (7), "Isoquinoline alkaloid biosynthesis" (6), "Splicer" (6) and "Protein processing in endoplasmic reticulum" (9), which were different from the functional metabolic pathways of down-regulated proteins. Down-regulated proteins were involved in metabolic pathways,…”