Effects of endogenous ascorbic acid on the distribution of photosynthetic electron flow in rice leaves

2019 ◽  
Vol 70 (10) ◽  
pp. 849
Author(s):  
Qilei Zhang ◽  
Minling Cai ◽  
Lina Lu ◽  
Hui Gao ◽  
Changlian Peng
Keyword(s):  
Ascorbic Acid ◽  
Photosynthetic Rate ◽  
Carbon Fixation ◽  
Higher Plants ◽  
Rice Yield ◽  
Oryza Sativa L ◽  
Electron Flow ◽  
Wild Type ◽  
Photosynthetic Electron Flow ◽  
Rice Leaves

Ascorbic acid (Asc) is one of the major antioxidants in plants. l-Galactono-1,4-lactone dehydrogenase (GLDH) is an enzyme that catalyses the last step of Asc biosynthesis in higher plants. In this study the effects of endogenous Asc on the distribution of photosynthetic electron flow were investigated in wild-type (ZH-11) rice (Oryza sativa L.) and in GLDH-overexpressing (GO-2) and GLDH-suppressed (GI-2) transgenic rice. The ratio of photosynthetic electron flow distributed to Rubisco-dependent carboxylation was highest in GO-2, whereas other electron flows in addition to carbon fixation were highest in GI-2 after flowering. Further examination showed that the photosynthetic electron flow, GLDH content and reactive oxygen species-scavenging ability were highest in GO-2 and lowest in GI-2. Therefore, the senescence of leaves was faster in GI-2 but slower in GO-2 compared with ZH-11. In addition, leaves with higher Asc content had more Rubisco content and a superior photosynthetic rate, which increased rice yield. These results suggest that increasing the endogenous Asc content of rice delays senescence, maintains a higher photosynthetic rate and results in more photosynthetic electron flow distributed to Rubisco-dependent carboxylation, ultimately leading to increased rice yield.

scholarly journals Transcription Profile Analysis of Chlorophyll Biosynthesis in Leaves of Wild-Type and Chlorophyll b-Deficient Rice (Oryza sativa L.)

Agriculture ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 401
Author(s):  
Minh Khiem Nguyen ◽  
Tin-Han Shih ◽  
Szu-Hsien Lin ◽  
Jun-Wei Lin ◽  
Hoang Chinh Nguyen ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Core Protein ◽  
Profile Analysis ◽  
Oryza Sativa L ◽  
Electron Flow ◽  
Chlorophyll Biosynthesis ◽  
Wild Type ◽  
Transcription Analysis ◽  
Chl A ◽  
Chl Biosynthesis

Photosynthesis is an essential biological process and a key approach for raising crop yield. However, photosynthesis in rice is not fully investigated. This study reported the photosynthetic properties and transcriptomic profiles of chlorophyll (Chl) b-deficient mutant (ch11) and wild-type rice (Oryza sativa L.). Chl b-deficient rice revealed irregular chloroplast development (indistinct membranes, loss of starch granules, thinner grana, and numerous plastoglobuli). Next-generation sequencing approach application revealed that the differential expressed genes were related to photosynthesis machinery, Chl-biosynthesis, and degradation pathway in ch11. Two genes encoding PsbR (PSII core protein), FtsZ1, and PetH genes, were found to be down-regulated. The expression of the FtsZ1 and PetH genes resulted in disrupted chloroplast cell division and electron flow, respectively, consequently reducing Chl accumulation and the photosynthetic capacity of Chl b-deficient rice. Furthermore, this study found the up-regulated expression of the GluRS gene, whereas the POR gene was down-regulated in the Chl biosynthesis and degradation pathways. The results obtained from RT-qPCR analyses were generally consistent with those of transcription analysis, with the exception of the finding that MgCH genes were up-regulated which enhance the important intermediate products in the Mg branch of Chl biosynthesis. These results indicate a reduction in the accumulation of both Chl a and Chl b. This study suggested that a decline in Chl accumulation is caused by irregular chloroplast formation and down-regulation of POR genes; and Chl b might be degraded via the pheophorbide b pathway, which requires further elucidation.

scholarly journals Enhancing Xanthine Dehydrogenase Activity is an Effective Way to Delay Leaf Senescence and Increase Rice Yield

2019 ◽  
Author(s):  
Ruicai Han ◽  
Xunfeng He ◽  
Xiaohua Pan ◽  
Qinghua Shi ◽  
Ziming Wu
Keyword(s):  
Chlorophyll Content ◽  
Leaf Senescence ◽  
Rice Yield ◽  
Xanthine Dehydrogenase ◽  
Purine Metabolism ◽  
Wild Type ◽  
Expression Levels ◽  
Over Expression ◽  
Ageing Processes ◽  
Rice Leaves

Abstract Xanthine dehydrogenase (XDH) is an important enzyme in purine metabolism. It is involved in regulation of the normal growth and non-biological stress-induced ageing processes in plants. The present study investigated XDH’s role in regulating rice leaf senescence. We measured physical characteristics, chlorophyll content and fluorescence parameters, active oxygen metabolism, and purine metabolism in wild-type Kitaake rice ( Oryza sativa L.), an OsXDH over-expression transgenic line ( OE9 ), and an OsXDH RNA interference line ( Ri3 ) during different growth stages. The expression patterns of the OsXDH gene confirmed that XDH was involved in the regulation of normal and abiotic stress-induced ageing processes in rice. There was no significant difference between the phenotypes of transgenic lines and wild type at the seedling stage, but differences were observed at the full heading and maturation stages. The OE9 plants were taller, with higher chlorophyll content, and their photosystems had stronger light energy absorption, transmission, dissipation, and distribution capacity, which ultimately improved the seed setting rate and 1000-seed weight. The opposite effect was found in the Ri3 plants. The OE9 line had a strong ability to remove reactive oxygen species, with increased accumulation of allantoin and alantoate. Experimental spraying of allantoin on leaves showed that it could alleviate chlorophyll degradation and decrease the content of H 2 O 2 and malonaldehyde (MDA) in rice leaves after the full heading stage. The urate oxidase gene ( UO ) expression levels in the interference line were significantly lower than those in the over-expression line and wild-type lines. The allantoinase ( ALN ) and allantoate amidinohydrolase ( AAH ) genes had significantly higher expression in the Ri3 plants than the in OE9 or wild-type plants, with OE9 plants showing the lowest levels. The senescence-related genes ACD1 , WRKY23 , WRKY53 , SGR , XERO1 , and GH27 in Ri3 plants had the highest expression levels, followed by those in the wild-type plants, with OE9 plants showing the lowest levels. These results suggest that enhanced activity of XDH can regulate the synthesis of urea-related substances, improve plant antioxidant capacity, effectively delay the ageing process in rice leaves, and increase rice yield.

scholarly journals Light Modulates the Biosynthesis and Organization of Cyanobacterial Carbon Fixation Machinery through Photosynthetic Electron Flow

2016 ◽  
Vol 171 (1) ◽  
pp. 530-541 ◽  
Author(s):  
Yaqi Sun ◽  
Selene Casella ◽  
Yi Fang ◽  
Fang Huang ◽  
Matthew Faulkner ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Electron Flow ◽  
Photosynthetic Electron Flow

scholarly journals High-Resolution Crystal Structure of Chloroplastic Ribose-5-Phosphate Isomerase from Chlamydomonas reinhardtii—An Enzyme Involved in the Photosynthetic Calvin-Benson Cycle

2020 ◽  
Vol 21 (20) ◽  
pp. 7787
Author(s):  
Théo Le Moigne ◽  
Pierre Crozet ◽  
Stéphane D. Lemaire ◽  
Julien Henri
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Metabolic Pathway ◽  
Carbon Fixation ◽  
Electron Flow ◽  
Structural Data ◽  
Post Translational Modifications ◽  
Photosynthetic Electron Flow ◽  
Biochemical Modeling ◽  
Experimental Structure

The Calvin–Benson cycle is the key metabolic pathway of photosynthesis responsible for carbon fixation and relies on eleven conserved enzymes. Ribose-5-phosphate isomerase (RPI) isomerizes ribose-5-phosphate into ribulose-5-phosphate and contributes to the regeneration of the Rubisco substrate. Plant RPI is the target of diverse post-translational modifications including phosphorylation and thiol-based modifications to presumably adjust its activity to the photosynthetic electron flow. Here, we describe the first experimental structure of a photosynthetic RPI at 1.4 Å resolution. Our structure confirms the composition of the catalytic pocket of the enzyme. We describe the homo-dimeric state of the protein that we observed in the crystal and in solution. We also map the positions of previously reported post-translational modifications and propose mechanisms by which they may impact the catalytic parameters. The structural data will inform the biochemical modeling of photosynthesis.

Herbicide and Quinone Binding to Chromatophores and Reaction Centers from Rhodobacter sphaeroides

1987 ◽  
Vol 42 (6) ◽  
pp. 690-692 ◽  
Author(s):  
Walter Oettmeier ◽  
Silvana Preuße
Keyword(s):  
Cytochrome C ◽  
Rhodobacter Sphaeroides ◽  
Higher Plants ◽  
Electron Flow ◽  
Reaction Centers ◽  
Type Reaction ◽  
Photosynthetic Electron Flow ◽  
Quinone Binding ◽  
Bacterial Reaction Centers

Besides s-triazine and triazinone herbicides the chromone stigmatellin and tetrahalogen-substituted 1.4-benzoquinones are inhibitors of photosynthetic electron flow from reduced cytochrome c to ubiquinone-6 in isolated bacterial reaction centers. With isolated bacterial chromatophores binding experiments with radiolabeled herbicides can be performed in a similar way as with thylakoids from higher plants. Tetrahalogen-substituted 1.4-benzoquinones in a Michael type reaction can add onto nucleophilic groups in proteins. In bacterial reaction centers, a [14C]tetra- bromo-1.4-benzoquinone (bromanil) exclusively binds to the H-subunit.

Enhancing Xanthine Dehydrogenase Activity is an Effective Way to Delay Leaf Senescence and Increase Rice Yield

2020 ◽  
Author(s):  
Ruicai Han ◽  
Xunfeng He ◽  
Xiaohua Pan ◽  
Qinghua Shi ◽  
Ziming Wu
Keyword(s):  
Chlorophyll Content ◽  
Leaf Senescence ◽  
Rice Yield ◽  
Xanthine Dehydrogenase ◽  
Purine Metabolism ◽  
Wild Type ◽  
Expression Levels ◽  
Over Expression ◽  
Ageing Processes ◽  
Rice Leaves

Abstract Xanthine dehydrogenase (XDH) is an important enzyme in purine metabolism. It is involved in regulation of the normal growth and non-biological stress-induced ageing processes in plants. The present study investigated XDH’s role in regulating rice leaf senescence. We measured physical characteristics, chlorophyll content and fluorescence parameters, active oxygen metabolism, and purine metabolism in wild-type Kitaake rice ( Oryza sativa L.), an OsXDH over-expression transgenic line ( OE9 ), and an OsXDH RNA interference line ( Ri3 ) during different growth stages. The expression patterns of the OsXDH gene confirmed that XDH was involved in the regulation of normal and abiotic stress-induced ageing processes in rice. There was no significant difference between the phenotypes of transgenic lines and wild type at the seedling stage, but differences were observed at the full heading and maturation stages. The OE9 plants were taller, with higher chlorophyll content, and their photosystems had stronger light energy absorption, transmission, dissipation, and distribution capacity, which ultimately improved the seed setting rate and 1000-seed weight. The opposite effect was found in the Ri3 plants. The OE9 line had a strong ability to remove reactive oxygen species, with increased accumulation of allantoin and alantoate. Experimental spraying of allantoin on leaves showed that it could alleviate chlorophyll degradation and decrease the content of H 2 O 2 and malonaldehyde (MDA) in rice leaves after the full heading stage. The urate oxidase gene ( UO ) expression levels in the interference line were significantly lower than those in the over-expression line and wild-type lines. The allantoinase ( ALN ) and allantoate amidinohydrolase ( AAH ) genes had significantly higher expression in the Ri3 plants than the in OE9 or wild-type plants, with OE9 plants showing the lowest levels. The senescence-related genes ACD1 , WRKY23 , WRKY53 , SGR , XERO1 , and GH27 in Ri3 plants had the highest expression levels, followed by those in the wild-type plants, with OE9 plants showing the lowest levels. These results suggest that enhanced activity of XDH can regulate the synthesis of urea-related substances, improve plant antioxidant capacity, effectively delay the ageing process in rice leaves, and increase rice yield.

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow

scholarly journals Uncoupling Salicylic Acid-Dependent Cell Death and Defense-Related Responses From Disease Resistance in the Arabidopsis Mutant acd5

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 341-350
Author(s):  
Jean T Greenberg ◽  
F Paul Silverman ◽  
Hua Liang
Keyword(s):  
Cell Death ◽  
Salicylic Acid ◽  
Disease Resistance ◽  
Pseudomonas Syringae ◽  
Higher Plants ◽  
Ethylene Signaling ◽  
Symptom Development ◽  
Wild Type ◽  
Dependent Cell ◽  
Arabidopsis Mutant

Abstract Salicylic acid (SA) is required for resistance to many diseases in higher plants. SA-dependent cell death and defense-related responses have been correlated with disease resistance. The accelerated cell death 5 mutant of Arabidopsis provides additional genetic evidence that SA regulates cell death and defense-related responses. However, in acd5, these events are uncoupled from disease resistance. acd5 plants are more susceptible to Pseudomonas syringae early in development and show spontaneous SA accumulation, cell death, and defense-related markers later in development. In acd5 plants, cell death and defense-related responses are SA dependent but they do not confer disease resistance. Double mutants with acd5 and nonexpressor of PR1, in which SA signaling is partially blocked, show greatly attenuated cell death, indicating a role for NPR1 in controlling cell death. The hormone ethylene potentiates the effects of SA and is important for disease symptom development in Arabidopsis. Double mutants of acd5 and ethylene insensitive 2, in which ethylene signaling is blocked, show decreased cell death, supporting a role for ethylene in cell death control. We propose that acd5 plants mimic P. syringae-infected wild-type plants and that both SA and ethylene are normally involved in regulating cell death during some susceptible pathogen infections.

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