Carotenoids are pigments required for photosynthesis, photoprotection and the production of carotenoid- derived hormones such as ABA and strigolactones. The carotenoid biosynthetic pathway bifurcates after lycopene to...Carotenoids are pigments required for photosynthesis, photoprotection and the production of carotenoid- derived hormones such as ABA and strigolactones. The carotenoid biosynthetic pathway bifurcates after lycopene to produce epsilon- and beta-carotenoids and this branch is critical for determining carotenoid composition. Here, we show how the branch point can be regulated by the chromatin-modifying histone methyltransferase, Set Domain Group 8 （SDG8） targeting the carotenoid isomerase （CRTISO）. SDG8 is required to maintain permissive expression of CRTISO during seedling development, in leaves, shoot apex, and some floral organs. The CRTISO and SDG8 promoters show overlapping tissue-specific patterns of reporter gene activity. Interestingly, CRTISO showed atypical reporter gene expression in terms of greater variability between different lines compared to the Cauliflower Mosaic Virus 35S promoter （CaMV35s） and ~LCY promoters, potentially due to chromosomal position effects. Regulation of the CRTISO promoter was dependent in part upon the presence or absence of SDG8. Knockouts of SDG8 （carotenoid and chloroplast regulation （ccrl）） and CRTISO （ccr2） result in altered carotenoid composition and this could be restored in ccr2 using the CaMV35s or CRTISO promoters. In contrast, varying degrees of GUS expression and carotenoid complementation by CRTISO overexpression using CaMV35S or CRTISO promoters in the ccrl background demonstrated that both the CRTISO promoter and open reading frame are necessary for SDG8-mediated expression of CRTISO.展开更多
In Chlamydomonas reinhardtii, the major protease involved in the maintenance of photosynthetic machinery in thylakoid membranes, the FtsH protease, mostly forms large hetero-oligomers （-1 MDa） comprising FtsH1 and F...In Chlamydomonas reinhardtii, the major protease involved in the maintenance of photosynthetic machinery in thylakoid membranes, the FtsH protease, mostly forms large hetero-oligomers （-1 MDa） comprising FtsH1 and FtsH2 subunits, whatever the light intensity for growth. Upon high light exposure, the FtsH subunits display a shorter half-life, which is counterbalanced by an increase in FTSH1/2 mRNA levels, resulting in the modest upregulation of FtsH1/2 proteins. Furthermore, we found that high light increases the protease activity through a hitherto unnoticed redox-controlled reduction of intermolecular disulfide bridges. We iso- lated a Chlamydomonas FTSH1 promoter-deficient mutant, ftsh1-3, resulting from the insertion of a TOC1 transposon, in which the high light-induced upregulation of FTSH1 gene expression is largely lost. In ftsh1- 3, the abundance of FtsH1 and FtsH2 proteins are loosely coupled （decreased by 70% and 30%, respectively） with no formation of large and stable homo-oligomers. Using strains exhibiting different accumulation levels of the FtsH1 subunit after complementation of ftsh1-3, we demonstrate that high light tolerance is tightly correlated with the abundance of the FtsH protease. Thus, the response of Chlamydomonas to light stress involves higher levels of FtsH 1/2 subunits associated into large complexes with increased proteolytic activity.展开更多
The nuclear-encoded factors and the photosynthetic apparatus have been studied extensively during chloroplast biogenesis.However,many questions regarding these processes remain unanswered,particularly in perennial woo...The nuclear-encoded factors and the photosynthetic apparatus have been studied extensively during chloroplast biogenesis.However,many questions regarding these processes remain unanswered,particularly in perennial woody plants.As a model material of woody plants,poplar not only has very significant value of research,but also possesses economic and ecological properties.This study reports the Populus trichocarpa DJ-1C(PtrDJ1C)factor,encoded by a nuclear gene,and a member of the DJ-1 superfamily.PtrDJ1C knock-out with the CRISPR/Cas9 system resulted in different albino phenotypes.Chlorophyll fluorescence and immunoblot analyses showed that the levels of photosynthetic complex proteins decreased significantly.Moreover,the transcript level of plastid-encoded RNA polymerase-dependent genes and the splicing efficiency of several introns were affected in the mutant line.Furthermore,rRNA accumulation was abnormal,leading to developmental defects in chloroplasts and affecting lignin accumulation.We concluded that the PtrDJ1C protein is essential for early chloroplast development and lignin deposition in poplar.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
为研究不同类型愈伤组织的叶绿体活性氧(ROS)代谢相关基因表达,探讨尾叶桉再生型愈伤组织转绿和不定芽分化之间的关系,将9 d苗龄的尾叶桉(Eucalyptus urophylla S. T. Blake)幼苗下胚轴接种在添加N-苯基-N-噻唑基脲、6-苄氨基腺嘌呤、吲...为研究不同类型愈伤组织的叶绿体活性氧(ROS)代谢相关基因表达,探讨尾叶桉再生型愈伤组织转绿和不定芽分化之间的关系,将9 d苗龄的尾叶桉(Eucalyptus urophylla S. T. Blake)幼苗下胚轴接种在添加N-苯基-N-噻唑基脲、6-苄氨基腺嘌呤、吲哚-3-乙酸的标准平板计数琼脂培养基(SPCA)中,外植体先膨大形成白色愈伤组织,8周后分化形成不同类型的愈伤组织(绿色带芽点愈伤组织、绿色愈伤组织、红色愈伤组织、白色愈伤组织)。4种愈伤组织中叶绿素质量分数分别为0.24、0.18、0.07、0.03 mg/g。实时荧光定量多聚核苷酸链式反应(qPCR)检测叶绿体rbcL基因和6个ROS代谢相关基因(TDP1、SOD2、DAR1、TRM4、TRF2、WTR1)的表达。qPCR检测到8周前的白色愈伤组织中4个叶绿体基因rbcL、TDP1、SOD2和DAR1的转录。其中,rbcL、TDP1、SOD2的转录水平随愈伤组织块的膨大不断升高,DAR1基因转录水平则较低。8周后,叶绿体rbcL基因和6个活性氧代谢相关基因均在绿色带芽点愈伤组织、绿色愈伤组织、红色愈伤组织中转录。设定红色愈伤组织中对应基因的表达量为1,绿色愈伤组织中,上述7个叶绿体基因(rbcL、TDP1、SOD2、DAR1、TRM4、TRF2、WTR1)相对表达量分别为8.84、3.36、2.89、2.65、2.53、1.28和7.49,绿色带芽点愈伤组织中7个基因的相对表达量分别为19.57、3.72、4.59、3.53、4.73、3.08和4.12。结果表明,愈伤组织转绿和不定芽分化过程中,叶绿体发育开始启动、叶绿素大量合成、rbcL转录显著增强,叶绿体中与活性氧代谢相关基因的表达水平升高。展开更多
An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Souther...An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Southern-blotting, Northern-blotting and Western-blotting assays after selecting on resistant medium and incubating in the dark. The results展开更多
文摘Carotenoids are pigments required for photosynthesis, photoprotection and the production of carotenoid- derived hormones such as ABA and strigolactones. The carotenoid biosynthetic pathway bifurcates after lycopene to produce epsilon- and beta-carotenoids and this branch is critical for determining carotenoid composition. Here, we show how the branch point can be regulated by the chromatin-modifying histone methyltransferase, Set Domain Group 8 （SDG8） targeting the carotenoid isomerase （CRTISO）. SDG8 is required to maintain permissive expression of CRTISO during seedling development, in leaves, shoot apex, and some floral organs. The CRTISO and SDG8 promoters show overlapping tissue-specific patterns of reporter gene activity. Interestingly, CRTISO showed atypical reporter gene expression in terms of greater variability between different lines compared to the Cauliflower Mosaic Virus 35S promoter （CaMV35s） and ~LCY promoters, potentially due to chromosomal position effects. Regulation of the CRTISO promoter was dependent in part upon the presence or absence of SDG8. Knockouts of SDG8 （carotenoid and chloroplast regulation （ccrl）） and CRTISO （ccr2） result in altered carotenoid composition and this could be restored in ccr2 using the CaMV35s or CRTISO promoters. In contrast, varying degrees of GUS expression and carotenoid complementation by CRTISO overexpression using CaMV35S or CRTISO promoters in the ccrl background demonstrated that both the CRTISO promoter and open reading frame are necessary for SDG8-mediated expression of CRTISO.
文摘In Chlamydomonas reinhardtii, the major protease involved in the maintenance of photosynthetic machinery in thylakoid membranes, the FtsH protease, mostly forms large hetero-oligomers （-1 MDa） comprising FtsH1 and FtsH2 subunits, whatever the light intensity for growth. Upon high light exposure, the FtsH subunits display a shorter half-life, which is counterbalanced by an increase in FTSH1/2 mRNA levels, resulting in the modest upregulation of FtsH1/2 proteins. Furthermore, we found that high light increases the protease activity through a hitherto unnoticed redox-controlled reduction of intermolecular disulfide bridges. We iso- lated a Chlamydomonas FTSH1 promoter-deficient mutant, ftsh1-3, resulting from the insertion of a TOC1 transposon, in which the high light-induced upregulation of FTSH1 gene expression is largely lost. In ftsh1- 3, the abundance of FtsH1 and FtsH2 proteins are loosely coupled （decreased by 70% and 30%, respectively） with no formation of large and stable homo-oligomers. Using strains exhibiting different accumulation levels of the FtsH1 subunit after complementation of ftsh1-3, we demonstrate that high light tolerance is tightly correlated with the abundance of the FtsH protease. Thus, the response of Chlamydomonas to light stress involves higher levels of FtsH 1/2 subunits associated into large complexes with increased proteolytic activity.
基金supported by the National Natural Science Foundation of China(Grant Nos.32201516,91954202)the Youth Top-notch Talent Program of Hebei Education Department(BJK2022028)+1 种基金National Training Program of Innovation and Entrepreneurship for Undergraduates(Grant Nos.S202110022037,G202010022075)the funding of Hebei North University(XJ2021013)。
文摘The nuclear-encoded factors and the photosynthetic apparatus have been studied extensively during chloroplast biogenesis.However,many questions regarding these processes remain unanswered,particularly in perennial woody plants.As a model material of woody plants,poplar not only has very significant value of research,but also possesses economic and ecological properties.This study reports the Populus trichocarpa DJ-1C(PtrDJ1C)factor,encoded by a nuclear gene,and a member of the DJ-1 superfamily.PtrDJ1C knock-out with the CRISPR/Cas9 system resulted in different albino phenotypes.Chlorophyll fluorescence and immunoblot analyses showed that the levels of photosynthetic complex proteins decreased significantly.Moreover,the transcript level of plastid-encoded RNA polymerase-dependent genes and the splicing efficiency of several introns were affected in the mutant line.Furthermore,rRNA accumulation was abnormal,leading to developmental defects in chloroplasts and affecting lignin accumulation.We concluded that the PtrDJ1C protein is essential for early chloroplast development and lignin deposition in poplar.
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.
文摘为研究不同类型愈伤组织的叶绿体活性氧(ROS)代谢相关基因表达,探讨尾叶桉再生型愈伤组织转绿和不定芽分化之间的关系,将9 d苗龄的尾叶桉(Eucalyptus urophylla S. T. Blake)幼苗下胚轴接种在添加N-苯基-N-噻唑基脲、6-苄氨基腺嘌呤、吲哚-3-乙酸的标准平板计数琼脂培养基(SPCA)中,外植体先膨大形成白色愈伤组织,8周后分化形成不同类型的愈伤组织(绿色带芽点愈伤组织、绿色愈伤组织、红色愈伤组织、白色愈伤组织)。4种愈伤组织中叶绿素质量分数分别为0.24、0.18、0.07、0.03 mg/g。实时荧光定量多聚核苷酸链式反应(qPCR)检测叶绿体rbcL基因和6个ROS代谢相关基因(TDP1、SOD2、DAR1、TRM4、TRF2、WTR1)的表达。qPCR检测到8周前的白色愈伤组织中4个叶绿体基因rbcL、TDP1、SOD2和DAR1的转录。其中,rbcL、TDP1、SOD2的转录水平随愈伤组织块的膨大不断升高,DAR1基因转录水平则较低。8周后,叶绿体rbcL基因和6个活性氧代谢相关基因均在绿色带芽点愈伤组织、绿色愈伤组织、红色愈伤组织中转录。设定红色愈伤组织中对应基因的表达量为1,绿色愈伤组织中,上述7个叶绿体基因(rbcL、TDP1、SOD2、DAR1、TRM4、TRF2、WTR1)相对表达量分别为8.84、3.36、2.89、2.65、2.53、1.28和7.49,绿色带芽点愈伤组织中7个基因的相对表达量分别为19.57、3.72、4.59、3.53、4.73、3.08和4.12。结果表明,愈伤组织转绿和不定芽分化过程中,叶绿体发育开始启动、叶绿素大量合成、rbcL转录显著增强,叶绿体中与活性氧代谢相关基因的表达水平升高。
文摘An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Southern-blotting, Northern-blotting and Western-blotting assays after selecting on resistant medium and incubating in the dark. The results
