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Score: 25.00 |
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| Title: Rice Chlorina-1 and Chlorina-9 encode ChlD and ChlI subunits of Mg-chelatase , a key enzyme for chlorophyll synthesis and chloroplast development .
| | Author: Zhang H Li J Yoo JH Yoo SC Cho SH Koh HJ Seo HS Paek NC .
| | Journal: Plant Mol . Biol . Citation: V : 62 ( 3 ) P : 325-37 Year: 2006 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub16915519 Accession (PMID): 16915519 | | Abstract: Photosynthetic organisms exhibit a green color due to the accumulation of chlorophyll pigments in chloroplasts .
Mg-protoporphyrin IX chelatase ( Mg-chelatase ) comprises three subunits ( ChlH , ChlD and ChlI ) and catalyzes the insertion of Mg ( 2+ ) into protoporphyrin IX , the last common intermediate precursor in both chlorophyll and heme biosyntheses , to produce Mg-protoporphyrin IX ( MgProto ) .
Chlorophyll deficiency in higher plants results in chlorina ( yellowish-green ) phenotype .
To date , 10 chlorina ( chl ) mutants have been isolated in rice , but the corresponding genes have not yet been identified .
Rice Chl1 and Chl9 genes were mapped to chromosome 3 and isolated by map-based cloning .
A missense mutation occurred in a highly conserved amino acid of ChlD in the chl1 mutant and ChlI in the chl9 mutant .
Ultrastructural analyses have revealed that the grana are poorly stacked , resulting in the underdevelopment of chloroplasts .
In the seedlings fed with aminolevulinate-dipyridyl in darkness , MgProto levels in the chl1 and chl9 mutants decreased up to 25% and 31% of that in wild-type , respectively , indicating that the Mg-chelatase activity is significantly reduced , causing the eventual decrease in chlorophyll synthesis .
Furthermore , Northern blot analysis indicated that the nuclear genes encoding the three subunits of Mg-chelatase and LhcpII in chl1 mutant are expressed about 2-fold higher than those in WT , but are not altered in the chl9 mutant .
This result indicates that the ChlD subunit participates in negative feedback regulation of plastid-to-nucleus in the expression of nuclear genes encoding chloroplast proteins , but not the ChlI subunit . | Matching Sentences:
[ Sen. 2, subscore: 4.00 ]: Mg-protoporphyrin IX chelatase ( Mg-chelatase ) comprises three subunits ( ChlH , ChlD and ChlI ) and catalyzes the insertion of Mg ( 2+ ) into protoporphyrin IX , the last common intermediate precursor in both chlorophyll and heme biosyntheses , to produce Mg-protoporphyrin IX ( MgProto ) .
[ Sen. 6, subscore: 4.00 ]: A missense mutation occurred in a highly conserved amino acid of ChlD in the chl1 mutant and ChlI in the chl9 mutant .
[ Sen. 8, subscore: 3.00 ]: In the seedlings fed with aminolevulinate-dipyridyl in darkness , MgProto levels in the chl1 and chl9 mutants decreased up to 25% and 31% of that in wild-type , respectively , indicating that the Mg-chelatase activity is significantly reduced , causing the eventual decrease in chlorophyll synthesis .
[ Sen. 10, subscore: 3.00 ]: This result indicates that the ChlD subunit participates in negative feedback regulation of plastid-to-nucleus in the expression of nuclear genes encoding chloroplast proteins , but not the ChlI subunit .
[ Sen. 1, subscore: 2.00 ]: Photosynthetic organisms exhibit a green color due to the accumulation of chlorophyll pigments in chloroplasts .
[ Sen. 3, subscore: 2.00 ]: Chlorophyll deficiency in higher plants results in chlorina ( yellowish-green ) phenotype .
[ Sen. 4, subscore: 2.00 ]: To date , 10 chlorina ( chl ) mutants have been isolated in rice , but the corresponding genes have not yet been identified .
[ Sen. 5, subscore: 2.00 ]: Rice Chl1 and Chl9 genes were mapped to chromosome 3 and isolated by map-based cloning .
[ Sen. 9, subscore: 2.00 ]: Furthermore , Northern blot analysis indicated that the nuclear genes encoding the three subunits of Mg-chelatase and LhcpII in chl1 mutant are expressed about 2-fold higher than those in WT , but are not altered in the chl9 mutant .
[ Sen. 7, subscore: 1.00 ]: Ultrastructural analyses have revealed that the grana are poorly stacked , resulting in the underdevelopment of chloroplasts .
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Score: 24.00 |
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| Title: Chloroplast chlB gene is required for light-independent chlorophyll accumulation in Chlamydomonas reinhardtii .
| | Author: Liu XQ Xu H Huang C | | Journal: Plant Mol . Biol . Citation: V : 23 ( 2 ) P : 297-308 Year: 1993 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub8219066 Accession (PMID): 8219066 | | Abstract: Light-independent chlorophyll synthesis occurs in some algae , lower plants , and gymnosperms , but not in angiosperms .
We have identified a new chloroplast gene , chlB , that is required for the light-independent accumulation of chlorophyll in the green alga Chlamydomonas reinhardtii .
The chlB gene was cloned , sequenced , and then disrupted by performing particle gun-mediated chloroplast transformation .
The resulting homoplasmic mutant was unable to accumulate chlorophyll in the dark and thus exhibited a yellow-in-the-dark phenotype .
The chlB gene encodes a polypeptide of 688 amino acid residues , and is distinct from two previously characterized chloroplast genes ( chlN and chlL ) also required for light-independent chlorophyll accumulation in C reinhardtii .
Three unidentified open reading frames in chloroplast genomes of liverwort , black pine , and Chlamydomonas moewusii were also identified as chlB genes , based on their striking sequence similarities to the C reinhardtii chlB gene .
A chlB-like gene is absent in chloroplast genomes of tobacco and rice , consistent with the lack of light-independent chlorophyll synthesis in these plants .
Polypeptides encoded by the chloroplast chlB genes also show significant sequence similarities with the bchB gene product of Rhodobacter capsulatus .
Comparisons among the chloroplast chlB and the bacterial bchB gene products revealed five highly conserved sequence areas that are interspersed by four stretches of highly variable and probably insertional sequences .
| Matching Sentences:
[ Sen. 5, subscore: 5.00 ]: The chlB gene encodes a polypeptide of 688 amino acid residues , and is distinct from two previously characterized chloroplast genes ( chlN and chlL ) also required for light-independent chlorophyll accumulation in C reinhardtii .
[ Sen. 2, subscore: 4.00 ]: We have identified a new chloroplast gene , chlB , that is required for the light-independent accumulation of chlorophyll in the green alga Chlamydomonas reinhardtii .
[ Sen. 6, subscore: 4.00 ]: Three unidentified open reading frames in chloroplast genomes of liverwort , black pine , and Chlamydomonas moewusii were also identified as chlB genes , based on their striking sequence similarities to the C reinhardtii chlB gene .
[ Sen. 7, subscore: 3.00 ]: A chlB-like gene is absent in chloroplast genomes of tobacco and rice , consistent with the lack of light-independent chlorophyll synthesis in these plants .
[ Sen. 3, subscore: 2.00 ]: The chlB gene was cloned , sequenced , and then disrupted by performing particle gun-mediated chloroplast transformation .
[ Sen. 8, subscore: 2.00 ]: Polypeptides encoded by the chloroplast chlB genes also show significant sequence similarities with the bchB gene product of Rhodobacter capsulatus .
[ Sen. 9, subscore: 2.00 ]: Comparisons among the chloroplast chlB and the bacterial bchB gene products revealed five highly conserved sequence areas that are interspersed by four stretches of highly variable and probably insertional sequences .
[ Sen. 1, subscore: 1.00 ]: Light-independent chlorophyll synthesis occurs in some algae , lower plants , and gymnosperms , but not in angiosperms .
[ Sen. 4, subscore: 1.00 ]: The resulting homoplasmic mutant was unable to accumulate chlorophyll in the dark and thus exhibited a yellow-in-the-dark phenotype .
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Score: 20.00 |
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| Title: Seasonal changes of chlorophyll content in field-grown rice crops and their relationships with growth .
| | Author: Yang CM Lee YJ .
| | Journal: Proc . Natl . Sci . Counc . Repub .
China B Citation: V : 25 ( 4 ) P : 233-8 Year: 2001 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub11699571 Accession (PMID): 11699571 | | Abstract: Field experiments were conducted on the experimental farm of the Taiwan Agricultural Research Institute ( TARI ) to examine seasonal changes in the amounts of chlorophylls in leaves and whole plants of rice ( Oryza sativa L cv .
Tainung 67 ) grown in the first and the second crop seasons in 1998 .
Chlorophyll ( Chl ) differences between two crops and their relationships with growth were also investigated .
The differences in climate conditions between the two crop seasons were quite phenomenal and led to different rates of plant growth and amounts of chlorophyll produced during the growth periods .
Seasonal changes in Chla , Chlb , and total Chl were curvilinear in style , with Chla making up the major portion of total chlorophyll .
Young plants of rice began with lower levels of chlorophyll , which increased as the plants developed , and decreased as the plants aged .
A significant increase in chlorophyll occurred in the early stage of the second crop compared to that of the first crop , and the difference was maintained throughout the growing season .
When the unit time transformation technique was used to exclude the difference in growth rate , the curves of the chlorophylls ( Chla , Chlb , and total ChI ) were similar in the two crops , but plants grown in the second crop season had higher levels of chlorophylls at the same time unit scale .
Generally , the ratio of Chla to Chlb ( Chla/Chlb ) decreased after transplanting , indicating a significant reduction ( p < 0 . 01 ) in the green-to-yellow pigment relationship .
Plants grown in the first crop had higher Chla/Chlb ratios than those grown in the second crop , especially in leaf blades .
Good agreement was found between growth traits and the respective total Chl cotent from regression analyses , and these growth traits were highly correlated with total Chl ( R2 > 0 . 8 ) .
However , rice plants grown in the first crop showed a higher levels of plant growth and leaf area at the same chlorophyll level than those grown in the second crop .
These results suggest that rice plants grown in the first crop may exhibit better growth and production than those grown in the second crop under normal growing conditions . | Matching Sentences:
[ Sen. 5, subscore: 5.00 ]: Seasonal changes in Chla , Chlb , and total Chl were curvilinear in style , with Chla making up the major portion of total chlorophyll .
[ Sen. 8, subscore: 4.00 ]: When the unit time transformation technique was used to exclude the difference in growth rate , the curves of the chlorophylls ( Chla , Chlb , and total ChI ) were similar in the two crops , but plants grown in the second crop season had higher levels of chlorophylls at the same time unit scale .
[ Sen. 3, subscore: 2.00 ]: Chlorophyll ( Chl ) differences between two crops and their relationships with growth were also investigated .
[ Sen. 9, subscore: 2.00 ]: Generally , the ratio of Chla to Chlb ( Chla/Chlb ) decreased after transplanting , indicating a significant reduction ( p < 0 . 01 ) in the green-to-yellow pigment relationship .
[ Sen. 11, subscore: 2.00 ]: Good agreement was found between growth traits and the respective total Chl cotent from regression analyses , and these growth traits were highly correlated with total Chl ( R2 > 0 . 8 ) .
[ Sen. 1, subscore: 1.00 ]: Field experiments were conducted on the experimental farm of the Taiwan Agricultural Research Institute ( TARI ) to examine seasonal changes in the amounts of chlorophylls in leaves and whole plants of rice ( Oryza sativa L cv .
[ Sen. 4, subscore: 1.00 ]: The differences in climate conditions between the two crop seasons were quite phenomenal and led to different rates of plant growth and amounts of chlorophyll produced during the growth periods .
[ Sen. 6, subscore: 1.00 ]: Young plants of rice began with lower levels of chlorophyll , which increased as the plants developed , and decreased as the plants aged .
[ Sen. 7, subscore: 1.00 ]: A significant increase in chlorophyll occurred in the early stage of the second crop compared to that of the first crop , and the difference was maintained throughout the growing season .
[ Sen. 12, subscore: 1.00 ]: However , rice plants grown in the first crop showed a higher levels of plant growth and leaf area at the same chlorophyll level than those grown in the second crop .
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Score: 16.00 |
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| Title: A chlorophyll-deficient rice mutant with impaired chlorophyllide esterification in chlorophyll biosynthesis .
| | Author: Wu Z Zhang X He B Diao L Sheng S Wang J Guo X Su N Wang L Jiang L Wang C Zhai H Wan J | | Journal: Plant Physiol Citation: V : 145 P : 29-40 Year: 2007 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub17535821 Accession (PMID): 17535821 | | Abstract: Chlorophyll ( Chl ) synthase catalyzes esterification of chlorophyllide to complete the last step of Chl biosynthesis .
Although the Chl synthases and the corresponding genes from various organisms have been well characterized , Chl synthase mutants have not yet been reported in higher plants .
In this study , a rice ( Oryza Sativa ) Chl-deficient mutant , yellow-green leaf1 ( ygl1 ) , was isolated , which showed yellow-green leaves in young plants with decreased Chl synthesis , increased level of tetrapyrrole intermediates , and delayed chloroplast development .
Genetic analysis demonstrated that the phenotype of ygl1 was caused by a recessive mutation in a nuclear gene .
The ygl1 locus was mapped to chromosome 5 and isolated by map-based cloning .
Sequence analysis revealed that it encodes the Chl synthase and its identity was verified by transgenic complementation .
A missense mutation was found in a highly conserved residue of YGL1 in the ygl1 mutant , resulting in reduction of the enzymatic activity .
YGL1 is constitutively expressed in all it issues , and its expression is not significantly affected in the ygl1 mutant .
Interestingly , the mRNA expression of the cab1R gene encoding the Chl a/b-binding protein was severely suppressed in the ygl1 mutant .
Moreover , the expression of some nuclear genes associated with Chl biosynthesis or chloroplast development was also affected in ygl1 seedlings .
These results indicate that the expression of nuclear genes encoding various chloroplast proteins might be feedback regulated by the level of Chl or Chl precursors .
| Matching Sentences:
[ Sen. 1, subscore: 4.00 ]: Chlorophyll ( Chl ) synthase catalyzes esterification of chlorophyllide to complete the last step of Chl biosynthesis .
[ Sen. 3, subscore: 3.00 ]: In this study , a rice ( Oryza Sativa ) Chl-deficient mutant , yellow-green leaf1 ( ygl1 ) , was isolated , which showed yellow-green leaves in young plants with decreased Chl synthesis , increased level of tetrapyrrole intermediates , and delayed chloroplast development .
[ Sen. 11, subscore: 3.00 ]: These results indicate that the expression of nuclear genes encoding various chloroplast proteins might be feedback regulated by the level of Chl or Chl precursors .
[ Sen. 2, subscore: 2.00 ]: Although the Chl synthases and the corresponding genes from various organisms have been well characterized , Chl synthase mutants have not yet been reported in higher plants .
[ Sen. 10, subscore: 2.00 ]: Moreover , the expression of some nuclear genes associated with Chl biosynthesis or chloroplast development was also affected in ygl1 seedlings .
[ Sen. 6, subscore: 1.00 ]: Sequence analysis revealed that it encodes the Chl synthase and its identity was verified by transgenic complementation .
[ Sen. 9, subscore: 1.00 ]: Interestingly , the mRNA expression of the cab1R gene encoding the Chl a/b-binding protein was severely suppressed in the ygl1 mutant .
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Score: 15.00 |
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| Title: Differential changes in degradation of chlorophyll-protein complexes of photosystem I and photosystem II during flag leaf senescence of rice .
| | Author: Tang Y Wen X Lu C | | Journal: Plant Physiol . Biochem . Citation: V : 43 ( 2 ) P : 193-201 Year: 2005 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub15820668 Accession (PMID): 15820668 | | Abstract: The stability of chlorophyll-protein complexes of photosystem I ( PSI ) and photosystem II ( PSII ) was investigated by chlorophyll ( Chl ) fluorescence spectroscopy , absorption spectra and native green gel separation system during flag leaf senescence of two rice varieties ( IIyou 129 and Shanyou 63 ) grown under outdoor conditions .
During leaf senescence , photosynthetic CO ( 2 ) assimilation rate , carboxylase activity of Rubisco , chlorophyll and carotenoids contents , and the chlorophyll a/b ratio decreased significantly .
The 77 K Chl fluorescence emission spectra of thylakoid membranes from mature leaves had two peaks at around 685 and 735 nm emitting mainly from PSII and PSI , respectively .
The total Chl fluorescence yields of PSI and PSII decreased significantly with senescence progressing .
However , the decrease in the Chl fluorescence yield of PSI was greater than in the yield of PSII , suggesting that the rate of degradation in chlorophyll-protein complexes of PSI was greater than in chlorophyll-protein complexes of PSII .
The fluorescence yields for all chlorophyll-protein complexes decreased significantly with leaf senescence in two rice varieties but the extents of their decrease were significantly different .
The greatest decrease in the Chl fluorescence yield was in PSI core , followed by LHCI , CP47 , CP43 , and LHCII .
These results indicate that the rate of degradation for each chlorophyll-protein complex was different and the order for the stability of chlorophyll-protein complexes during leaf senescence was : LHCII>CP43>CP47>LHCI>PSI core , which was partly supported by the green gel electrophoresis of the chlorophyll-protein complexes . | Matching Sentences:
[ Sen. 1, subscore: 3.00 ]: The stability of chlorophyll-protein complexes of photosystem I ( PSI ) and photosystem II ( PSII ) was investigated by chlorophyll ( Chl ) fluorescence spectroscopy , absorption spectra and native green gel separation system during flag leaf senescence of two rice varieties ( IIyou 129 and Shanyou 63 ) grown under outdoor conditions .
[ Sen. 5, subscore: 3.00 ]: However , the decrease in the Chl fluorescence yield of PSI was greater than in the yield of PSII , suggesting that the rate of degradation in chlorophyll-protein complexes of PSI was greater than in chlorophyll-protein complexes of PSII .
[ Sen. 8, subscore: 3.00 ]: These results indicate that the rate of degradation for each chlorophyll-protein complex was different and the order for the stability of chlorophyll-protein complexes during leaf senescence was : LHCII>CP43>CP47>LHCI>PSI core , which was partly supported by the green gel electrophoresis of the chlorophyll-protein complexes .
[ Sen. 2, subscore: 2.00 ]: During leaf senescence , photosynthetic CO ( 2 ) assimilation rate , carboxylase activity of Rubisco , chlorophyll and carotenoids contents , and the chlorophyll a/b ratio decreased significantly .
[ Sen. 3, subscore: 1.00 ]: The 77 K Chl fluorescence emission spectra of thylakoid membranes from mature leaves had two peaks at around 685 and 735 nm emitting mainly from PSII and PSI , respectively .
[ Sen. 4, subscore: 1.00 ]: The total Chl fluorescence yields of PSI and PSII decreased significantly with senescence progressing .
[ Sen. 6, subscore: 1.00 ]: The fluorescence yields for all chlorophyll-protein complexes decreased significantly with leaf senescence in two rice varieties but the extents of their decrease were significantly different .
[ Sen. 7, subscore: 1.00 ]: The greatest decrease in the Chl fluorescence yield was in PSI core , followed by LHCI , CP47 , CP43 , and LHCII .
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