Photoinhibition and loss of photosystem II reaction centre proteins during senescence of soybean leaves. Enhancement of photoinhibition by the ‘stay‐green’ mutation <i>cytG</i>

Guiamet, Juan José; Tyystjärvi, Esa; Tyystjärvi, Taina; John, Isaac; Kairavuo, Marja; Pichersky, Eran; Noodén, Larry D.

doi:10.1034/j.1399-3054.2002.1150317.x

Cited by 49 publications

(50 citation statements)

References 41 publications

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“…Therefore, these investigators assumed that extended greenness in cytG occurred in response to the inhibition of Chl b degradation, which correlated with substantial preservation of LHCII. In contrast, the breakdown of other Chl-protein complexes, including LHCI, occurred normally in cytG (Guiamet et al 2002). However, the instability of LHCI is inconsistent with the proposed role of inhibition of Chl b degradation in cytG, because LHCI also contains Chl b.…”

Section: Extended Greenness and Degradation Of Chl And/or Proteinmentioning

confidence: 40%

“…The PSII reaction center complexes were degraded earlier than the lightharvesting complex II (LHCII), whereas the PSI antenna complexes were degraded earlier than the PSI reaction center complexes, indicating that degradation of the PSI antenna is regulated by a mechanism entirely different from that controlling the degradation of PSII (Oh and Lee 1996, Yamazaki et al 2000, Guiamet et al 2002. However, the disassembly process was different in the ore10 and ore11 mutants, where other than LHCII, all Chl-protein complexes (LHCI, PSI reaction center, PSII reaction center) degraded gradually.…”

Section: Introductionmentioning

confidence: 99%

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Increased Stability of LHCII by Aggregate Formation during Dark-Induced Leaf Senescence in the Arabidopsis Mutant, ore10

Moon

Lee

2003

Plant and Cell Physiology

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Leaf senescence in a stay-green mutant of Arabidopsis thaliana, ore10, was investigated during dark-incubation of its detached leaves. During this dark-induced senescence (DIS), Chl loss was delayed in ore10 mutants, as compared with wild type, but the rate of decline in the photochemical efficiency of PSII was not delayed in mutant leaves. After 2 d of DIS, native green gel electrophoresis of ore 10 leaf proteins resulted in a significant amount of pigment remaining as aggregates on top of the stacking gel. In addition, the accumulation of aggregates coincided with the emergence of a new band near 700 nm (F 699 ) in the 77 K fluorescence emission spectrum of the aggregates. At 4 d, F 699 became a major band, both in the isolated aggregates and in intact leaves. Prolonged treatment with detergents revealed that light-harvesting complex II (LHCII) remaining after 2 d was highly stable, and the accumulation of aggregates coincided with the appearance of truncated LHCII in senescing ore10 leaves. These results suggest that increased LHCII stability is due to the formation of aggregates of trimmed LHCII. Thus, the LHCII protein degradation step that follows proteolysis of its terminal peptides is a possible lesion site of the ore10 mutant.

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Section: Extended Greenness and Degradation Of Chl And/or Proteinmentioning

confidence: 40%

Section: Introductionmentioning

confidence: 99%

Increased Stability of LHCII by Aggregate Formation during Dark-Induced Leaf Senescence in the Arabidopsis Mutant, ore10

Moon

Lee

2003

Plant and Cell Physiology

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“…The ore10 locus in Arabidopsis was recently mapped to within 2 cM of the RCI1b locus on chromosome 5 (Oh et al, 2006), whereas two SGN genes are located on chromosome 4. The cytoplasmically inherited stay-green mutation in soybean, cytG, also retains LHCPII, but not LHCPI, during monocarpic senescence (Guiamé t et al, 1991(Guiamé t et al, , 2002, suggesting that the degradation of LHCPI and LHCPII occurs in different metabolic pathways and that other chloroplast components must be required for LHCPII disassembly in senescing chloroplasts. Thus, future work is necessary to elucidate the nature of chloroplast proteins involved in the molecular events of LHCP disassembly.…”

Section: Sgr Interacts With Lhcpii For Lhcp Destabilization In Senescmentioning

confidence: 99%

The Senescence-Induced Staygreen Protein Regulates Chlorophyll Degradation

et al. 2007

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Loss of green color in leaves results from chlorophyll (Chl) degradation in chloroplasts, but little is known about how Chl catabolism is regulated throughout leaf development. Using the staygreen (sgr) mutant in rice (Oryza sativa), which maintains greenness during leaf senescence, we identified Sgr, a senescence-associated gene encoding a novel chloroplast protein. Transgenic rice overexpressing Sgr produces yellowish-brown leaves, and Arabidopsis thaliana pheophorbide a oxygenase-impaired mutants exhibiting a stay-green phenotype during dark-induced senescence have reduced expression of Sgr homologs, indicating that Sgr regulates Chl degradation at the transcriptional level. We show that the leaf staygreenness of the sgr mutant is associated with a failure in the destabilization of the light-harvesting chlorophyll binding protein (LHCP) complexes of the thylakoid membranes, which is a prerequisite event for the degradation of Chls and LHCPs during senescence. Transient overexpression of Sgr in Nicotiana benthamiana and an in vivo pull-down assay show that Sgr interacts with LHCPII, indicating that the Sgr-LHCPII complexes are formed in the thylakoid membranes. Thus, we propose that in senescing leaves, Sgr regulates Chl degradation by inducing LHCPII disassembly through direct interaction, leading to the degradation of Chls and Chl-free LHCPII by catabolic enzymes and proteases, respectively.

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“…In sid, the degradation of photosynthetic proteins, including LHCII and the ferredoxin binding protein of PSI, is inhibited, and chlorophyll a is more stable than chlorophyll b during leaf senescence (Thomas et al, 1999). cytG in soybean (Glycine max) is a cytoplasmic mutation in which degradation of LHCII is selectively inhibited and chlorophyll b is more stable than chlorophyll a (Guiamé t et al, 2002). Very recently, Lethal Leaf Spot1 (LLS1)/Accelerated Cell Death1 was identified as pheophorbide a oxygenase.…”

Section: Introductionmentioning

confidence: 99%

Rice NON-YELLOW COLORING1 Is Involved in Light-Harvesting Complex II and Grana Degradation during Leaf Senescence

et al. 2007

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Chlorophyll degradation is an aspect of leaf senescence, which is an active process to salvage nutrients from old tissues. non-yellow coloring1 (nyc1) is a rice (Oryza sativa) stay-green mutant in which chlorophyll degradation during senescence is impaired. Pigment analysis revealed that degradation of not only chlorophylls but also light-harvesting complex II (LHCII)-bound carotenoids was repressed in nyc1, in which most LHCII isoforms were selectively retained during senescence. Ultrastructural analysis of nyc1 chloroplasts revealed that large and thick grana were present even in the late stage of senescence, suggesting that degradation of LHCII is required for the proper degeneration of thylakoid membranes. Mapbased cloning of NYC1 revealed that it encodes a chloroplast-localized short-chain dehydrogenase/reductase (SDR) with three transmembrane domains. The predicted structure of the NYC1 protein and the phenotype of the nyc1 mutant suggest the possibility that NYC1 is a chlorophyll b reductase. Although we were unable to detect the chlorophyll b reductase activity of NYC1, NOL (for NYC1-like), a protein closely related to NYC1 in rice, showed chlorophyll b reductase activity in vitro. We suggest that NYC1 and NOL encode chlorophyll b reductases with divergent functions. Our data collectively suggest that the identified SDR protein NYC1 plays essential roles in the regulation of LHCII and thylakoid membrane degradation during senescence. INTRODUCTIONThe final step of leaf development is senescence, which is an active process to salvage nutrients from old leaves. Leaf yellowing, which is caused by unmasking of preexisting carotenoids by chlorophyll degradation, is a good indicator of senescence (Matile, 2000). Most chlorophyll exists in protein complexes in leaves, because free chlorophyll photooxidatively damages cells. Chlorophyll a is a component of several protein complexes, including the photosystem I (PSI) and photosystem II (PSII) reaction center complexes and the cytochrome b 6 f complex. Chlorophyll b exists only in the light-harvesting chlorophyll a/b-protein complex (LHCP). LHCP binds chlorophyll a, chlorophyll b, and carotenoids (neoxanthin, violaxanthin, and lutein) (Liu et al., 2004). Chlorophyll b is thought to be important for the stability of LHCP (Bellemare et al., 1982). PSI-associated light-harvesting complex I (LHCI) and PSII-associated LHCII proteins are encoded by the Lhca and Lhcb gene families, respectively. LHCPs are localized in the thylakoid membrane. Lhcb1, -2, and -3 are major LHCII proteins and form trimers, but Lhcb4, -5, and -6 occur as monomers. LHCII is localized predominantly in grana, the stacking region of the thylakoid membrane. LHCII has been thought to play an important role in the formation of grana (Allen and Forsberg, 2001).The chlorophyll synthesis pathway has been well characterized, and most, if not all, genes encoding enzymes involved in chlorophyll synthesis have been isolated (Nagata et al., 2005). On the other hand, the chlorophyll degradation pathway is less...

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Photoinhibition and loss of photosystem II reaction centre proteins during senescence of soybean leaves. Enhancement of photoinhibition by the ‘stay‐green’ mutation cytG

Cited by 49 publications

References 41 publications

Increased Stability of LHCII by Aggregate Formation during Dark-Induced Leaf Senescence in the Arabidopsis Mutant, ore10

Increased Stability of LHCII by Aggregate Formation during Dark-Induced Leaf Senescence in the Arabidopsis Mutant, ore10

The Senescence-Induced Staygreen Protein Regulates Chlorophyll Degradation

Rice NON-YELLOW COLORING1 Is Involved in Light-Harvesting Complex II and Grana Degradation during Leaf Senescence

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