High light induced photooxidation （HLIP） usually leads to leaf premature senescence and causes great yield loss in winter wheat. In order to explore the genetic control of wheat tolerance to HLIP stress, a quantitat...High light induced photooxidation （HLIP） usually leads to leaf premature senescence and causes great yield loss in winter wheat. In order to explore the genetic control of wheat tolerance to HLIP stress, a quantitative trait loci （QTL） analysis was conducted on a set of doubled haploid population, derived from two winter wheat cultivars. Actual values of chlorophyll content （Chl）, minimum fluorescence level （Fo）, maximum fluorescence level （Fm）, and the maximum quan^m efficiency of photosystem II （Fv/Fm） under both HLIP and non-stress conditions as well as the ratios of HLIP to non-stress were evaluated. HLIP considerably reduced Chl, Fm, and Fv/Fm, but in- creased Fo, compared with that under non-stress condition. A total of 27, 16, and 28 QTLs were associated with the investigated traits under HLIP and non-stress and the ratios of HLIP to non-stress, respectively. Most of the QTLs for the ratios of HLIP to non-stress collocated or nearly linked with those detected under HLIP condition. HLIP-induced QTLs were mapped on 15 chromosomes, involving in 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 4D, 5B, 6A, 6B, 7A, and 7D while those expressed under non-stress condition involved in nine chromosomes, includ- ing 1B, 1D, 2A, 2B, 3B, 4A, 5A, 5B, and 7A. The expression patterns of QTLs under HLIP condition were different from that under non-stress condition except for six loci on five chromosomes. The phenotypic variance explained by individual QTL ranged from 5.0% to 19.7% under HLIP, 8.3% to 20.8% under non-stress, and 4.9% to 20.2% for the ratios of HLIP to non-stress, respectively. Some markers, for example, Xgwm192 and WMC331 on 4D regulating Chl, Fo, Fm, and Fv/Fm under HLIP condition, might be used in marker assistant selection.展开更多
Carotenoids, a class of natural pigments found in all photosynthetic organisms, are involved in a variety of physiological processes, including coloration, photoprotection, biosynthesis of abscisic acid （ABA） and ch...Carotenoids, a class of natural pigments found in all photosynthetic organisms, are involved in a variety of physiological processes, including coloration, photoprotection, biosynthesis of abscisic acid （ABA） and chloroplast biogenesis. Although carotenoid biosynthesis has been well studied biochemically, the genetic basis of the pathway is not well understood. Here, we report the characterization of two allelic Arabidopsis mutants, spontaneous cell death1-1 （spcl-1） and spc1-2. The weak allele spc1-1 mutant showed characteristics of bleached leaves, accumulation of superoxide and mosaic cell death. The strong mutant allele spc1-2 caused a complete arrest of plant growth and development shortly after germination, leading to a seedling-lethal phenotype. Genetic and molecular analyses indicated that SPC1 encodes a putative ζ-carotene desaturase （ZDS） in the carotenoid biosynthesis pathway. Analysis of carotenoids revealed that several major carotenoid compounds downstream of SPC 1/ZDS were substantially reduced in spc1-1, suggesting that SPC 1 is a functional ZDS. Consistent with the downregulated expression of CAO and PORB, the chlorophyll content was decreased in spc1-1 plants. In addition, expression of Lhcb1. 1, Lhcbl. 4 and RbcS was absent in spc1-2, suggesting the possible involvement of carotenoids in the plastid-to-nucleus retrograde signaling. The spc1-1 mutant also displays an ABA-deficient phenotype that can be partially rescued by the externally supplied phytohormone. These results suggest that SPC1/ZDS is essential for biosynthesis of carotenoids and plays a crucial role in plant growth and development.展开更多
RNA polymerase transcriptional pausing represents a major checkpoint in transcription in bacteria and metazoans,but it is unknown whether this phenomenon occurs in plant organelles.Here,we report that transcriptional ...RNA polymerase transcriptional pausing represents a major checkpoint in transcription in bacteria and metazoans,but it is unknown whether this phenomenon occurs in plant organelles.Here,we report that transcriptional pausing occurs in chloroplasts.We found that mTERF5 specifically and positively regulates the transcription of chloroplast psbEFLJ in Arabidopsis thaliana that encodes four key subunits of photosystem II.We found that mTERF5 causes the plastid-encoded RNA polymerase(PEP)complex to pause at psbEFLJ by binding to the+30 to+51 region of double-stranded DNA.Moreover,we revealed that mTERF5 interacts with pTAC6,an essential subunit of the PEP complex,although pTAC6 is not involved in the transcriptional pausing at psbEFLJ.We showed that mTERF5 recruits additional pTAC6 to the transcriptionally paused region of psbEFLJ,and the recruited pTAC6 proteins could be assembled into the PEP complex to regulate psbEFLJ transcription.Taken together,our findings shed light on the role of transcriptional pausing in chloroplast transcription in plants.展开更多
Flowering time(heading date)is a critical agronomic trait that determines the yield and regional adaptability of crops.Heading date 1(Hd1)is a central regulator of photoperiodic flowering in rice(Oryza sativa).However...Flowering time(heading date)is a critical agronomic trait that determines the yield and regional adaptability of crops.Heading date 1(Hd1)is a central regulator of photoperiodic flowering in rice(Oryza sativa).However,how the homeostasis of Hd1 protein is achieved is poorly understood.Here,we report that the nuclear autophagy pathway mediates Hd1 degradation in the dark to regulate flowering.Loss of autophagy function results in an accumulation of Hd1 and delays flowering under both short-day and long-day conditions.In the dark,nucleus-localized Hd1 is recognized as a substrate for autophagy and is subjected to vacuolar degradation via the autophagy protein OsATG8.The Hd1-0sATG8 interaction is required for autophagic degradation of Hd1 in the dark.Our study reveals a new mechanism by which Hd1 protein homeostasis is regulated by autophagy to control rice flowering.Our study also indicates that the regulation of flowering by autophagic degradation of Hd1 orthologs may have arisen over the course of mesangiosperm evolution,which would have increased their flexibility and adaptability to the environment by modulating flowering time.展开更多
Glutathione reductase（GR） catalyzes the reduction of glutathione disulfide（GSSG） to reduced glutathione（GSH）and participates in the ascorbate-glutathione cycle, which scavenges H_2O_2. Here, we report that chlor...Glutathione reductase（GR） catalyzes the reduction of glutathione disulfide（GSSG） to reduced glutathione（GSH）and participates in the ascorbate-glutathione cycle, which scavenges H_2O_2. Here, we report that chloroplastic/mitochondrial GR2 is an important regulator of leaf senescence. Seed development of the homozygous gr2 knockout mutant was blocked at the globular stage. Therefore, to investigate the function of GR2 in leaf senescence, we generated transgenic Arabidopsis plants with decreased GR2 using RNAi. The GR2 RNAi plants displayed early onset of age-dependent and darkand H2O2-induced leaf senescence, which was accompanied by the induction of the senescence-related marker genes SAG12 and SAG13. Furthermore, transcriptome analysis revealed that genes related to leaf senescence, oxidative stress, and phytohormone pathways were upregulated directly before senescence in RNAi plants. In addition, H2O2 accumulated to higher levels in RNAi plants than in wild-type plants and the levels of H_2O_2 peaked in RNAi plants directly before the early onset of leaf senescence. RNAi plants showed a greater decrease in GSH/GSSG levels than wild-type plants during leaf development. Our results suggest that GR2 plays an important role in leaf senescence by modulating H_2O_2 and glutathione signaling in Arabidopsis.展开更多
Phytyl-diphosphate, which provides phytyl moieties as a common substrate in both tocopherol and phyllo- quinone biosynthesis, derives from de novo isoprenoid biosynthesis or a salvage pathway via phytol phos- phorylat...Phytyl-diphosphate, which provides phytyl moieties as a common substrate in both tocopherol and phyllo- quinone biosynthesis, derives from de novo isoprenoid biosynthesis or a salvage pathway via phytol phos- phorylation. However, very little is known about the role and origin of the phytyl moiety for phylloquinone biosynthesis. Since VTE6, a phytyl-phosphate kinase, is a key enzyme for phytol phosphorylation, we char- acterized Arabidopsis vte6 mutants to gain insight into the roles of phytyl moieties in phylloquinone biosyn- thesis and of phylloquinone in photosystem I （PSI） biogenesis. The VTE6 knockout mutants vte6-1 and vte6-2 lacked detectable phylloquinone, whereas the phylloquinone content in the VTE6 knockdown mutant vte6-3 was 90% lower than that in wild-type. In vte6 mutants, PSI function was impaired and accu- mulation of the PSI complex was defective. The PSI core subunits PsaA/B were efficiently synthesized and assembled into the PSI complex in vte6-3. However, the degradation rate of PSI subunits in the assembled PSI complex was more rapid in vte6-3 than in wild-type. In vte6-3, PSI was more susceptible to high-light damage than in wild-type. Our results provide the first genetic evidence that the phytol phosphorylation pathway is essential for phylloquinone biosynthesis, and that phylloquinone is required for PSI complex stability.展开更多
Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago.During subsequent coevolution with the nuclear genome,the chloroplast genome has remained independent,albeit strongly re...Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago.During subsequent coevolution with the nuclear genome,the chloroplast genome has remained independent,albeit strongly reduced,with its own transcriptional machinery and distinct features,such as chloroplast-specific innovations in gene expression and complicated post-transcriptional processing.Light activates the expression of chloroplast genes via mechanisms that optimize photosynthesis,minimize photodamage,and prioritize energy investments.Over the past few years,studies have moved from describing phases of chloroplast gene expression to exploring the underlying mechanisms.In this review,we focus on recent advances and emerging principles that govern chloroplast gene expression in land plants.We discuss engineering of pentatricopeptide repeat proteins and its biotechnological effects on chloroplast RNA research;new techniques for characterizing the molecular mechanisms of chloroplast gene expression;and important aspects of chloroplast gene expression for improving crop yield and stress tolerance.We also discuss biological and mechanistic questions that remain to be answered in the future.展开更多
To gain a better understanding of the molec-ular mechanisms of photosystem!(PSI)biogenesis,wecharacterized the Arabidopsis thaliana photosystem l bio-genesis factor 2(pbf2)mutant,which lacks PSl complex.PBF2 encodes a...To gain a better understanding of the molec-ular mechanisms of photosystem!(PSI)biogenesis,wecharacterized the Arabidopsis thaliana photosystem l bio-genesis factor 2(pbf2)mutant,which lacks PSl complex.PBF2 encodes a P-class pentatricopeptide repeat(PPR)protein.In the pbf2 mutants,we observed a striking de-crease in the transcript level of only one gene,thechloroplast gene ycf3,which is essential for PSl assembly.Further analysis of ycf3 transcripts showed that PBF2 isspecifically required for the splicing of ycf3 intron 1.Computational prediction of binding sequences and elec-trophoretic mobility shift assays reveal that PBF2 specifi-cally binds to a sequence in ycf3 intron 1.Moreover,we found that PBF2 interacted with two general factors forgroup ll intron splicing CHLOROPLAST RNA SPLICING2-AsSOCIATED FACTOR1(CAF1)and CAF2,and facilitated theassociation of these two factors with ycf3 intron 1.Ourresults suggest that PBF2 is specifically required for thesplicing of ycf3 intron 1 through cooperating with CAF1and CAF2.Our results also suggest that additional proteinsare required to contribute to the specificity of CAF-dependent group ll intron splicing.展开更多
Adventitious roots form from non-root tissues as part of normal development or in response to stress or wounding.The root primordia form in the source tissue,and during emergence the adventitious roots penetrate the i...Adventitious roots form from non-root tissues as part of normal development or in response to stress or wounding.The root primordia form in the source tissue,and during emergence the adventitious roots penetrate the inner cell layers and the epidermis;however,the mechanisms underlying this emergence remain largely unexplored.Here,we report that a regulatory module composed of the AP2/ERF transcription factor ABSCISIC ACID INSENSITIVE 4(ABI4),the MAP kinases MPK3 and MPK6,and the phosphatase PP2C12 plays an important role in the emergence of junction adventitious roots(J-ARs)from the root-hypocotyl junctions in Arabidopsis thaliana.ABI4 negatively regulates J-AR emergence,preventing the accumulation of reactive oxygen species and death of epidermal cells,which would otherwise facilitate J-AR emergence.Phosphorylation by MPK3/MPK6 activates ABI4 and dephosphorylation by PP2C12 inactivates ABI4.MPK3/MPK6 also directly phosphorylate and inactivate PP2C12 during J-AR emergence.We propose that this"double-check"mechanism increases the robustness of MAP kinase signaling and finely regulates the local programmed cell death required for J-AR emergence.展开更多
Photosynthesis is a process that converts solar energy to chemical energy in many different organisms, ranging from plants to bacteria. Photosynthesis provides all the food we eat and all the fossil fuel we use. Photo...Photosynthesis is a process that converts solar energy to chemical energy in many different organisms, ranging from plants to bacteria. Photosynthesis provides all the food we eat and all the fossil fuel we use. Photosynthesis has long been studied in order to understand its underlying mechanisms and then to apply this knowledge to the production of energy and food for the needs of our society. The 15th International Congress on Photosynthesis will be held in Beijing from August 22 to 27, 2010. It will feature eminent plenary speakers and state-of-the-art symposium speakers who are at the cutting edge of discovery in their fields and provide an exciting scientific program which will cover the breadth and depth of photosynthesis from molecular to global. To celebrate this congress, Journal of Integrative Plant Biology （JIPB） publishes a special issue on photosynthesis which includes reviews of the recent progress on the various aspects of photosynthesis.展开更多
基金supported by the National Key Basic Research Program (Nos. 2009CB118506, 2004CB117205, and 2002CB111304)the Natural Science Foundation of China (No. 30330390)+1 种基金the Knowledge Innovation Program (KIP) key project from the Chinese Academy of Sciences (No. KSCX1-YW-03)the National Science and Tech-nology Supporting Program (No. 2006GB24910466)
文摘High light induced photooxidation （HLIP） usually leads to leaf premature senescence and causes great yield loss in winter wheat. In order to explore the genetic control of wheat tolerance to HLIP stress, a quantitative trait loci （QTL） analysis was conducted on a set of doubled haploid population, derived from two winter wheat cultivars. Actual values of chlorophyll content （Chl）, minimum fluorescence level （Fo）, maximum fluorescence level （Fm）, and the maximum quan^m efficiency of photosystem II （Fv/Fm） under both HLIP and non-stress conditions as well as the ratios of HLIP to non-stress were evaluated. HLIP considerably reduced Chl, Fm, and Fv/Fm, but in- creased Fo, compared with that under non-stress condition. A total of 27, 16, and 28 QTLs were associated with the investigated traits under HLIP and non-stress and the ratios of HLIP to non-stress, respectively. Most of the QTLs for the ratios of HLIP to non-stress collocated or nearly linked with those detected under HLIP condition. HLIP-induced QTLs were mapped on 15 chromosomes, involving in 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 4D, 5B, 6A, 6B, 7A, and 7D while those expressed under non-stress condition involved in nine chromosomes, includ- ing 1B, 1D, 2A, 2B, 3B, 4A, 5A, 5B, and 7A. The expression patterns of QTLs under HLIP condition were different from that under non-stress condition except for six loci on five chromosomes. The phenotypic variance explained by individual QTL ranged from 5.0% to 19.7% under HLIP, 8.3% to 20.8% under non-stress, and 4.9% to 20.2% for the ratios of HLIP to non-stress, respectively. Some markers, for example, Xgwm192 and WMC331 on 4D regulating Chl, Fo, Fm, and Fv/Fm under HLIP condition, might be used in marker assistant selection.
基金grants from National Natural Science Foundation of China （Grant Nos. 30330360, 30125025 , 30221002） Chinese Academy of Sciences （Grant No. KSCX2- YW-N-015）
文摘Carotenoids, a class of natural pigments found in all photosynthetic organisms, are involved in a variety of physiological processes, including coloration, photoprotection, biosynthesis of abscisic acid （ABA） and chloroplast biogenesis. Although carotenoid biosynthesis has been well studied biochemically, the genetic basis of the pathway is not well understood. Here, we report the characterization of two allelic Arabidopsis mutants, spontaneous cell death1-1 （spcl-1） and spc1-2. The weak allele spc1-1 mutant showed characteristics of bleached leaves, accumulation of superoxide and mosaic cell death. The strong mutant allele spc1-2 caused a complete arrest of plant growth and development shortly after germination, leading to a seedling-lethal phenotype. Genetic and molecular analyses indicated that SPC1 encodes a putative ζ-carotene desaturase （ZDS） in the carotenoid biosynthesis pathway. Analysis of carotenoids revealed that several major carotenoid compounds downstream of SPC 1/ZDS were substantially reduced in spc1-1, suggesting that SPC 1 is a functional ZDS. Consistent with the downregulated expression of CAO and PORB, the chlorophyll content was decreased in spc1-1 plants. In addition, expression of Lhcb1. 1, Lhcbl. 4 and RbcS was absent in spc1-2, suggesting the possible involvement of carotenoids in the plastid-to-nucleus retrograde signaling. The spc1-1 mutant also displays an ABA-deficient phenotype that can be partially rescued by the externally supplied phytohormone. These results suggest that SPC1/ZDS is essential for biosynthesis of carotenoids and plays a crucial role in plant growth and development.
基金the National Natural Science Foundation of China(reference number 31730102)the State Key Basic Research and Development Plan of China(reference number 2015CB150105)+2 种基金the Key Research Plan of Frontier Sciences of the Chinese Academy of Sciences(reference number QYZDJ-SSW-SMC003)the Strategic Priority Research Program of the Chinese Academy of Sciences(reference number XDB17030100)the National Key Scientific Instrument and Equipment Development Project of China(grant no.2013YQ030595).
文摘RNA polymerase transcriptional pausing represents a major checkpoint in transcription in bacteria and metazoans,but it is unknown whether this phenomenon occurs in plant organelles.Here,we report that transcriptional pausing occurs in chloroplasts.We found that mTERF5 specifically and positively regulates the transcription of chloroplast psbEFLJ in Arabidopsis thaliana that encodes four key subunits of photosystem II.We found that mTERF5 causes the plastid-encoded RNA polymerase(PEP)complex to pause at psbEFLJ by binding to the+30 to+51 region of double-stranded DNA.Moreover,we revealed that mTERF5 interacts with pTAC6,an essential subunit of the PEP complex,although pTAC6 is not involved in the transcriptional pausing at psbEFLJ.We showed that mTERF5 recruits additional pTAC6 to the transcriptionally paused region of psbEFLJ,and the recruited pTAC6 proteins could be assembled into the PEP complex to regulate psbEFLJ transcription.Taken together,our findings shed light on the role of transcriptional pausing in chloroplast transcription in plants.
基金supported by the National Key Research and Development Program of China(2020YFA0907602)the National Natural Science Foundation of China(31730102).
文摘Flowering time(heading date)is a critical agronomic trait that determines the yield and regional adaptability of crops.Heading date 1(Hd1)is a central regulator of photoperiodic flowering in rice(Oryza sativa).However,how the homeostasis of Hd1 protein is achieved is poorly understood.Here,we report that the nuclear autophagy pathway mediates Hd1 degradation in the dark to regulate flowering.Loss of autophagy function results in an accumulation of Hd1 and delays flowering under both short-day and long-day conditions.In the dark,nucleus-localized Hd1 is recognized as a substrate for autophagy and is subjected to vacuolar degradation via the autophagy protein OsATG8.The Hd1-0sATG8 interaction is required for autophagic degradation of Hd1 in the dark.Our study reveals a new mechanism by which Hd1 protein homeostasis is regulated by autophagy to control rice flowering.Our study also indicates that the regulation of flowering by autophagic degradation of Hd1 orthologs may have arisen over the course of mesangiosperm evolution,which would have increased their flexibility and adaptability to the environment by modulating flowering time.
基金supported by the National Natural Science Foundation of China(30970218)the State Key Basic Research and Development Plan of China(2015CB150105)
文摘Glutathione reductase（GR） catalyzes the reduction of glutathione disulfide（GSSG） to reduced glutathione（GSH）and participates in the ascorbate-glutathione cycle, which scavenges H_2O_2. Here, we report that chloroplastic/mitochondrial GR2 is an important regulator of leaf senescence. Seed development of the homozygous gr2 knockout mutant was blocked at the globular stage. Therefore, to investigate the function of GR2 in leaf senescence, we generated transgenic Arabidopsis plants with decreased GR2 using RNAi. The GR2 RNAi plants displayed early onset of age-dependent and darkand H2O2-induced leaf senescence, which was accompanied by the induction of the senescence-related marker genes SAG12 and SAG13. Furthermore, transcriptome analysis revealed that genes related to leaf senescence, oxidative stress, and phytohormone pathways were upregulated directly before senescence in RNAi plants. In addition, H2O2 accumulated to higher levels in RNAi plants than in wild-type plants and the levels of H_2O_2 peaked in RNAi plants directly before the early onset of leaf senescence. RNAi plants showed a greater decrease in GSH/GSSG levels than wild-type plants during leaf development. Our results suggest that GR2 plays an important role in leaf senescence by modulating H_2O_2 and glutathione signaling in Arabidopsis.
文摘Phytyl-diphosphate, which provides phytyl moieties as a common substrate in both tocopherol and phyllo- quinone biosynthesis, derives from de novo isoprenoid biosynthesis or a salvage pathway via phytol phos- phorylation. However, very little is known about the role and origin of the phytyl moiety for phylloquinone biosynthesis. Since VTE6, a phytyl-phosphate kinase, is a key enzyme for phytol phosphorylation, we char- acterized Arabidopsis vte6 mutants to gain insight into the roles of phytyl moieties in phylloquinone biosyn- thesis and of phylloquinone in photosystem I （PSI） biogenesis. The VTE6 knockout mutants vte6-1 and vte6-2 lacked detectable phylloquinone, whereas the phylloquinone content in the VTE6 knockdown mutant vte6-3 was 90% lower than that in wild-type. In vte6 mutants, PSI function was impaired and accu- mulation of the PSI complex was defective. The PSI core subunits PsaA/B were efficiently synthesized and assembled into the PSI complex in vte6-3. However, the degradation rate of PSI subunits in the assembled PSI complex was more rapid in vte6-3 than in wild-type. In vte6-3, PSI was more susceptible to high-light damage than in wild-type. Our results provide the first genetic evidence that the phytol phosphorylation pathway is essential for phylloquinone biosynthesis, and that phylloquinone is required for PSI complex stability.
基金supported by the National Key Research and Development Program of China(grant no.2020YFA0907600)the National Natural Science Foundation of China(grant nos.31730102 and 32000184)+1 种基金the Natural Science Foundation of Shandong Province(grant no.ZR2020QC023)the China Postdoctoral Science Foundation(grant no.2020M672093).
文摘Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago.During subsequent coevolution with the nuclear genome,the chloroplast genome has remained independent,albeit strongly reduced,with its own transcriptional machinery and distinct features,such as chloroplast-specific innovations in gene expression and complicated post-transcriptional processing.Light activates the expression of chloroplast genes via mechanisms that optimize photosynthesis,minimize photodamage,and prioritize energy investments.Over the past few years,studies have moved from describing phases of chloroplast gene expression to exploring the underlying mechanisms.In this review,we focus on recent advances and emerging principles that govern chloroplast gene expression in land plants.We discuss engineering of pentatricopeptide repeat proteins and its biotechnological effects on chloroplast RNA research;new techniques for characterizing the molecular mechanisms of chloroplast gene expression;and important aspects of chloroplast gene expression for improving crop yield and stress tolerance.We also discuss biological and mechanistic questions that remain to be answered in the future.
基金This work was supported by the National Natural Science Foundation of China(reference numbers 31730102 and 31401035)the Key Research Plan of Frontier Sciences of the Chinese Academy of Sciences(reference number QYZDJ-SSW-SMC003)。
文摘To gain a better understanding of the molec-ular mechanisms of photosystem!(PSI)biogenesis,wecharacterized the Arabidopsis thaliana photosystem l bio-genesis factor 2(pbf2)mutant,which lacks PSl complex.PBF2 encodes a P-class pentatricopeptide repeat(PPR)protein.In the pbf2 mutants,we observed a striking de-crease in the transcript level of only one gene,thechloroplast gene ycf3,which is essential for PSl assembly.Further analysis of ycf3 transcripts showed that PBF2 isspecifically required for the splicing of ycf3 intron 1.Computational prediction of binding sequences and elec-trophoretic mobility shift assays reveal that PBF2 specifi-cally binds to a sequence in ycf3 intron 1.Moreover,we found that PBF2 interacted with two general factors forgroup ll intron splicing CHLOROPLAST RNA SPLICING2-AsSOCIATED FACTOR1(CAF1)and CAF2,and facilitated theassociation of these two factors with ycf3 intron 1.Ourresults suggest that PBF2 is specifically required for thesplicing of ycf3 intron 1 through cooperating with CAF1and CAF2.Our results also suggest that additional proteinsare required to contribute to the specificity of CAF-dependent group ll intron splicing.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciencesthe Ministry of Agriculture of China(grant no.2016ZX08009003-005).
文摘Adventitious roots form from non-root tissues as part of normal development or in response to stress or wounding.The root primordia form in the source tissue,and during emergence the adventitious roots penetrate the inner cell layers and the epidermis;however,the mechanisms underlying this emergence remain largely unexplored.Here,we report that a regulatory module composed of the AP2/ERF transcription factor ABSCISIC ACID INSENSITIVE 4(ABI4),the MAP kinases MPK3 and MPK6,and the phosphatase PP2C12 plays an important role in the emergence of junction adventitious roots(J-ARs)from the root-hypocotyl junctions in Arabidopsis thaliana.ABI4 negatively regulates J-AR emergence,preventing the accumulation of reactive oxygen species and death of epidermal cells,which would otherwise facilitate J-AR emergence.Phosphorylation by MPK3/MPK6 activates ABI4 and dephosphorylation by PP2C12 inactivates ABI4.MPK3/MPK6 also directly phosphorylate and inactivate PP2C12 during J-AR emergence.We propose that this"double-check"mechanism increases the robustness of MAP kinase signaling and finely regulates the local programmed cell death required for J-AR emergence.
文摘Photosynthesis is a process that converts solar energy to chemical energy in many different organisms, ranging from plants to bacteria. Photosynthesis provides all the food we eat and all the fossil fuel we use. Photosynthesis has long been studied in order to understand its underlying mechanisms and then to apply this knowledge to the production of energy and food for the needs of our society. The 15th International Congress on Photosynthesis will be held in Beijing from August 22 to 27, 2010. It will feature eminent plenary speakers and state-of-the-art symposium speakers who are at the cutting edge of discovery in their fields and provide an exciting scientific program which will cover the breadth and depth of photosynthesis from molecular to global. To celebrate this congress, Journal of Integrative Plant Biology （JIPB） publishes a special issue on photosynthesis which includes reviews of the recent progress on the various aspects of photosynthesis.
