The deterioration in fruit quality of commercial tomatoes is a major concern of modern tomato breeding.However,the metabolism and genetics of fruit quality are poorly understood.Here,we performed transgenic and molecu...The deterioration in fruit quality of commercial tomatoes is a major concern of modern tomato breeding.However,the metabolism and genetics of fruit quality are poorly understood.Here,we performed transgenic and molecular biology experiments to reveal that tomato phytoene synthase 1(SlPSY1)is responsible for the accumulation of an important flavor chemical,6-methyl-5-hepten-2-one(MHO).To dissect the function of SlPSY1 in regulating fruit quality,we generated and analyzed a dataset encompassing over 2000 compounds detected by GC-MS and LC-MS/MS along with transcriptomic data.The combined results illustrated that SlPSY1 deficiency imparts novel flavor to yellow tomatoes with 236 volatiles significantly changed and improves fruit firmness,possibly due to accumulation of seven cutins.Further analysis indicated SlPSY1 is essential for carotenoid-derived metabolite biosynthesis by catalyzing prephytoene-PP(PPPP)to 15-cis-phytoene.Notably,we showed that SlPSY1 can influence the metabolic flux between carotenoid and flavonoid pathways,and this metabolic flux was confirmed by silencing SlCHS1.Our study provided insights into the multiple effects of SlPSY1 on tomato fruit metabolome and highlights the potential to produce high-quality fruit by rational design of SlPSY1 expression.展开更多
[Objective] The aim was to establish an HPLC method for determination of phytoene content in tomato ketchup. [Method] The chromatographic conditions were as follows： column, Agilent AT C18 （250 mm×4.6 mm, 5 μm...[Objective] The aim was to establish an HPLC method for determination of phytoene content in tomato ketchup. [Method] The chromatographic conditions were as follows： column, Agilent AT C18 （250 mm×4.6 mm, 5 μm）; mobile phase, methanol-THF （75：25）; detection wavelength, 287 nm; flow rate, 1.0 ml/min; column temperature, 30 ℃; sample size, 50 μl. [Result] There was a good linear relation- ship in the phytoene content range of 0.186-1.116μg. The average recovery rate was 103.8% with RSD of 1.47%. The phytoene content in the tomato ketchup sample was determined as 10.7 rag/100 g simple, accurate, rapid and reliable, and phytoene content in tomato ketchup. [Conclusion] The established method is it can be used for the determination of展开更多
With tomato paste as raw material, the optimal extraction process of phy- toene from tomato paste was explored by orthogonal experiment on the basis of single-factor experiments. The results showed that the optimal ex...With tomato paste as raw material, the optimal extraction process of phy- toene from tomato paste was explored by orthogonal experiment on the basis of single-factor experiments. The results showed that the optimal extraction process for phytoene from tomato paste was as follows： extractant, acetone; solid to liquid ratio, 10：1; extraction time, 40 min; extraction temperature, 45 ℃. The developed extrac- tion process was stable, reasonable and feasible. Under the optimal extraction pro- cess, the extraction rate of phytoene reached 0.044 4%.展开更多
Carotenoids play an important role in many physiological processes in plants and the phytoene desaturase gene （PDS3） encodes one of the important enzymes in the carotenoid biosynthesis pathway. Here we report the id...Carotenoids play an important role in many physiological processes in plants and the phytoene desaturase gene （PDS3） encodes one of the important enzymes in the carotenoid biosynthesis pathway. Here we report the identification and analysis of a T-DNA insertion mutant of PDS3 gene. Functional complementation confirmed that both the albino and dwarfphenotypes ofthepds3 mutant resulted from functional disruption of the PDS3 gene. Chloroplast development was arrested at the proplastid stage in thepds3 mutant. Further analysis showed that high level ofphytoene was accumulated in the pds3 mutant. Addition of exogenous GA3 could partially rescue the dwarf phenotype, suggesting that the dwarf phenotype ofthepds3 mutant might be due to GA deficiency. Microarray and RT-PCR analysis showed that disrupting PDS3 gene resulted in gene expression changes involved in at least 20 metabolic pathways, including the inhibition of many genes in carotenoid, chlorophyll, and GA biosynthesis pathways. Our data suggest that the accumulated phytoene in the pds3 mutant might play an important role in certain negative feedbacks to affect gene expression of diverse cellular pathways.展开更多
An efficient and simple method for constructing a genomic DNA library using a TAcloning vector is presented. It is based on the sonicative cleavage of genomic DNA and modification offragment ends with Taq DNA polymera...An efficient and simple method for constructing a genomic DNA library using a TAcloning vector is presented. It is based on the sonicative cleavage of genomic DNA and modification offragment ends with Taq DNA polymerase, followed by ligation using a TA vector. This method was ap-plied for cloning of the phytoene synthase gene crtB from Spirulina platensis. This method is useful whengenomic DNA cannot be efficiently digested with restriction enzymes, a problem often encountered duringthe construction of a genomic DNA library of cyanobacteria.展开更多
The unicellular green alga Dunaliella is outstanding for its ability of massive accumulation of carotenoids. To elucidate the carotenoids synthesis pathway in this alga,phytoene desaturase(pds) gene cDNA together with...The unicellular green alga Dunaliella is outstanding for its ability of massive accumulation of carotenoids. To elucidate the carotenoids synthesis pathway in this alga,phytoene desaturase(pds) gene cDNA together with its DNA sequences were isolated and their structures and functions analyzed. The full-length pds cDNA of 2290 bp(GenBank Accession No. DQ243892) was de-duced from RACE results,including untranslated 21 bp 5'-and 520 bp 3'-flanking regions and an open reading frame of 582 amino acids,coding a protein of 64.196 kDa. The DNA sequence of 2908 bp(GenBank Accession No. DQ845248) including five introns was obtained. The fifth intron was uncompleted and complex,including two bases' perfect repeats(GT) 10 and large different-sized repeats within the last 400 bp. The Southern blot hybridization result demonstrated that this gene occurred as a single copy in this species,and the quantitative RT-PCR result showed that the transcription of this gene was constitutive. The evolutional significance of pds was discussed.展开更多
A 2 149 bp full length phytoene desaturase (PDS) cDNA was first cloned from saffron (Crocus sativus L.) stigma using RT-PCR technique and a rapid amplification of cDNA end (RACE) strategy. The cDNA has an open reading...A 2 149 bp full length phytoene desaturase (PDS) cDNA was first cloned from saffron (Crocus sativus L.) stigma using RT-PCR technique and a rapid amplification of cDNA end (RACE) strategy. The cDNA has an open reading frame of 1 697 bp, which encodes a polypeptide of 565 amino acids. The coding region of the cDNA was inserted into a prokaryotic expression vector pET-21a(+) and over-expressed inE. coli BL21 (DE3). The fusion proteins were found largely in an insoluble inclusion bodies. The purified fusion protein was used to immunize rabbits to obtain polyclonal antiserum with titer of 1×105. Western blot analysis by using this particular antiserum showed that the higher expression level of PDS in mature stigma than in leaves and stamen, and the higher expression level of PDS in mature stigma than in young stigma. Key words saffron - carotenoids - phytoene desaturase - gene expression - antiserum - Western blot CLC number Q 781 - Q 786 Foundation item: Supported by the Doctoral Foundation of the Ministry of Education, P. R. China and the Young Science Foundation of Sichuan University (Grant 0020405505012)Biography: Bai Jie (1968-), female, Ph. D candidate, research direction: plant developmental biology and reproductive engineering.展开更多
Using the mRNA from the fruit of Cara Cara as the template, the cDNA of phytoene synthase （PSY） gene was amplified by reverse transcription polymerse chain reaction （RT-PCR）. Sequence analysis indicated that the c...Using the mRNA from the fruit of Cara Cara as the template, the cDNA of phytoene synthase （PSY） gene was amplified by reverse transcription polymerse chain reaction （RT-PCR）. Sequence analysis indicated that the cDNA was of 1 520 bp, which had an open reading frame of 1 308 bp and encoded a protein of 436 amino acids. The homology analysis showed that PSY of Cara Cara shared high similarities of nucleotides and deduced amino acids with those in other plants up to more than 75 and 70%, respectively. A putative signal transit peptide for plastid targeting was found in the N-terminal region of PSY. The mature forms of PSY included a transmembrane （TM） domain. The recombinant plasmid pET-CitPSY was constructed by subcloning the full coding sequence of PSY cDNA into pET-28 （＋）. After transformation of E. coli BL21 and induced by 1 mmol L^-1 isopropyl-β-D-thiogalacropyranoside （IPTG）, the fusion protein （6× His-PSY） with 52 kD was produced at a high level by prokaryotic expression system. The results of Western blot demonstrated that the fusion protein （6× His-PSY） could be recognized by anti-6 × His monoclonal antibody. The study could establish a basis for molecular improvement of Citrus fruit colors.展开更多
Phytoene synthase （PSY） is the crucial plastidial enzyme in the carotenoid biosynthetic pathway. However, its post-translational regulation remains elusive. Likewise, Clp protease constitutes a central part of the p...Phytoene synthase （PSY） is the crucial plastidial enzyme in the carotenoid biosynthetic pathway. However, its post-translational regulation remains elusive. Likewise, Clp protease constitutes a central part of the plastid protease network, but its substrates for degradation are not well known. In this study, we report that PSY is a substrate of the Clp protease. PSY was uncovered to physically interact with various Clp protease subunits （i.e., ClpS1, CIpC1, and CIpD）. High levels of PSY and several other carotenogenic enzyme proteins overac- cumulate in the clpcl, clpp4, and clprl-2 mutants. The overaccumulated PSY was found to be partially enzy- matically active. Impairment of Clp activity in clpcl results in a reduced rate of PSY protein turnover, further supporting the role of Clp protease in degrading PSY protein. On the other hand, the ORANGE （OR） protein, a major post-translational regulator of PSY with holdase chaperone activity, enhances PSY protein stability and increases the enzymatically active proportion of PSY in clpcl, counterbalancing CIp-mediated proteol- ysis in maintaining PSY protein homeostasis. Collectively, these findings provide novel insights into the qual- ity control of plastid-localized proteins and establish a hitherto unidentified post-translational regulatory mechanism of carotenogenic enzymes in modulating carotenoid biosynthesis in plants.展开更多
To understand the functional identification of large-scale genomic sequences in Forsythia,tobacco rattle virus(TRV)-mediated virus-induced gene silencing(VIGS),suitable for the plant,was explored in this study.The res...To understand the functional identification of large-scale genomic sequences in Forsythia,tobacco rattle virus(TRV)-mediated virus-induced gene silencing(VIGS),suitable for the plant,was explored in this study.The results showed that the TRV-mediated VIGS system could be successfully used in Forsythia for silencing the reporter gene FsPDS(Forsythia phytoene desaturase)using stem infiltration and leaf infiltrationmethods.All the treated plants were pruned below the injection site after 7–15 d infection;the FsPDS was silenced and typical photobleaching symptoms were observed in newly sprouted leaves at the whole-plant level.Meanwhile,this system has been successfully tested and verified through virus detection and qRT-PCR analysis.After the optimization,Forsythia magnesium chelatase subunit H(FsChlH)was silenced successfully in Forsythia using this system,resulting in yellow leaveswith decreased chlorophyll content.The system was stable,highly efficient and had greater rapidity and convenience,which made it suitable to study the function of genes related to physiological pathways such as growth and development,and metabolic regulation in Forsythia.展开更多
Eggplant （Solanum melongena） is an economically important vegetable requiring investigation into its various genomic functions. The current limitation in the investigation of genomic function in eggplant is the lack...Eggplant （Solanum melongena） is an economically important vegetable requiring investigation into its various genomic functions. The current limitation in the investigation of genomic function in eggplant is the lack of effective tools available for conducting functional assays. Virus-induced gene silencing （VIGS） has played a critical role in the functional genetic analyses. In this paper, TRV-mediated VIGS was successfully elicited in eggplant. We first cloned the CDS sequence of PDS （PHYTOENE DESATURASE） in eggplant and then silenced the PDS gene. Photo-bleaching was shown on the newly-developed leaves four weeks after agroinoculation, indicating that VIGS can be used to silence genes in eggplant. To further illustrate the reliability of VIGS in eggplant, we selected Chl H, Su and CLA1 as reporters to elicit VIGS using the high-pressure spray method. Suppression of Chl H and Su led to yellow leaves, while the depletion of CLA1 resulted in albino. In conclusion, four genes, PDS, Chl H, Su （Sulfur）, CLA1, were down-regulated significantly by VIGS, indicating that the VIGS system can be successfully applied in eggplant and is a reliable tool for the study of gene function.展开更多
The immutans （im） variegation mutant of Arabidopsis defines the gene for PTOX （plastid terminal oxidase）, a versatile plastoquinol oxidase in chloroplast membranes. In this report we used im to gain insight into t...The immutans （im） variegation mutant of Arabidopsis defines the gene for PTOX （plastid terminal oxidase）, a versatile plastoquinol oxidase in chloroplast membranes. In this report we used im to gain insight into the function of PTOX in etioplasts of dark-grown seedlings. We discovered that PTOX helps control the redox state of the plastoquinone （PQ） pool in these organelles, and that it plays an essential role in etioplast metabolism by participating in the desaturation reactions of carotenogenesis and in one or more redox pathways mediated by PGR5 （PROTON GRADIENT REGULATION 5） and NDH （NAD（P）H dehydrogenase）, both of which are central players in cyclic electron transport. We propose that these elements couple PTOX with electron flow from NAD（P）H to oxygen, and by analogy to chlororespiration （in chloroplasts） and chromorespiration （in chromoplasts）, we suggest that they define a respiratory process in etioplasts that we have termed ＂etiorespiration＂. We further show that the redox state of the PQ pool in etioplasts might control chlorophyll biosynthesis, perhaps by participating in mechanisms of retrograde （plastid- to-nucleus） signaling that coordinate biosynthetic and photoprotective activities required to poise the etioplast for light development. We conclude that PTOX is an important component of metabolism and redox sensing in etioplasts.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.31991185,31902019,32102384)National Key Research and Development Program of China(Grant No.2021YFF1000103)+2 种基金Key Research and Development Program of Guangdong Province(Grant No.2021B0707010005)Taishan Scholars Program of Shandong Province,China(2016-2020)supported by the Youth innovation Program of Chinese Academy of Agricultural Sciences(Grant No.Y2023QC05)。
文摘The deterioration in fruit quality of commercial tomatoes is a major concern of modern tomato breeding.However,the metabolism and genetics of fruit quality are poorly understood.Here,we performed transgenic and molecular biology experiments to reveal that tomato phytoene synthase 1(SlPSY1)is responsible for the accumulation of an important flavor chemical,6-methyl-5-hepten-2-one(MHO).To dissect the function of SlPSY1 in regulating fruit quality,we generated and analyzed a dataset encompassing over 2000 compounds detected by GC-MS and LC-MS/MS along with transcriptomic data.The combined results illustrated that SlPSY1 deficiency imparts novel flavor to yellow tomatoes with 236 volatiles significantly changed and improves fruit firmness,possibly due to accumulation of seven cutins.Further analysis indicated SlPSY1 is essential for carotenoid-derived metabolite biosynthesis by catalyzing prephytoene-PP(PPPP)to 15-cis-phytoene.Notably,we showed that SlPSY1 can influence the metabolic flux between carotenoid and flavonoid pathways,and this metabolic flux was confirmed by silencing SlCHS1.Our study provided insights into the multiple effects of SlPSY1 on tomato fruit metabolome and highlights the potential to produce high-quality fruit by rational design of SlPSY1 expression.
基金Supported by Special Fund for Small and Medium Enterprises of Shihezi in the Eighth Division of Xinjiang Production and Construction Corps(2013QY16)~~
文摘[Objective] The aim was to establish an HPLC method for determination of phytoene content in tomato ketchup. [Method] The chromatographic conditions were as follows： column, Agilent AT C18 （250 mm×4.6 mm, 5 μm）; mobile phase, methanol-THF （75：25）; detection wavelength, 287 nm; flow rate, 1.0 ml/min; column temperature, 30 ℃; sample size, 50 μl. [Result] There was a good linear relation- ship in the phytoene content range of 0.186-1.116μg. The average recovery rate was 103.8% with RSD of 1.47%. The phytoene content in the tomato ketchup sample was determined as 10.7 rag/100 g simple, accurate, rapid and reliable, and phytoene content in tomato ketchup. [Conclusion] The established method is it can be used for the determination of
文摘With tomato paste as raw material, the optimal extraction process of phy- toene from tomato paste was explored by orthogonal experiment on the basis of single-factor experiments. The results showed that the optimal extraction process for phytoene from tomato paste was as follows： extractant, acetone; solid to liquid ratio, 10：1; extraction time, 40 min; extraction temperature, 45 ℃. The developed extrac- tion process was stable, reasonable and feasible. Under the optimal extraction pro- cess, the extraction rate of phytoene reached 0.044 4%.
基金the National Natural Science Foundation of China （Grant No. 30470172）.
文摘Carotenoids play an important role in many physiological processes in plants and the phytoene desaturase gene （PDS3） encodes one of the important enzymes in the carotenoid biosynthesis pathway. Here we report the identification and analysis of a T-DNA insertion mutant of PDS3 gene. Functional complementation confirmed that both the albino and dwarfphenotypes ofthepds3 mutant resulted from functional disruption of the PDS3 gene. Chloroplast development was arrested at the proplastid stage in thepds3 mutant. Further analysis showed that high level ofphytoene was accumulated in the pds3 mutant. Addition of exogenous GA3 could partially rescue the dwarf phenotype, suggesting that the dwarf phenotype ofthepds3 mutant might be due to GA deficiency. Microarray and RT-PCR analysis showed that disrupting PDS3 gene resulted in gene expression changes involved in at least 20 metabolic pathways, including the inhibition of many genes in carotenoid, chlorophyll, and GA biosynthesis pathways. Our data suggest that the accumulated phytoene in the pds3 mutant might play an important role in certain negative feedbacks to affect gene expression of diverse cellular pathways.
文摘An efficient and simple method for constructing a genomic DNA library using a TAcloning vector is presented. It is based on the sonicative cleavage of genomic DNA and modification offragment ends with Taq DNA polymerase, followed by ligation using a TA vector. This method was ap-plied for cloning of the phytoene synthase gene crtB from Spirulina platensis. This method is useful whengenomic DNA cannot be efficiently digested with restriction enzymes, a problem often encountered duringthe construction of a genomic DNA library of cyanobacteria.
文摘The unicellular green alga Dunaliella is outstanding for its ability of massive accumulation of carotenoids. To elucidate the carotenoids synthesis pathway in this alga,phytoene desaturase(pds) gene cDNA together with its DNA sequences were isolated and their structures and functions analyzed. The full-length pds cDNA of 2290 bp(GenBank Accession No. DQ243892) was de-duced from RACE results,including untranslated 21 bp 5'-and 520 bp 3'-flanking regions and an open reading frame of 582 amino acids,coding a protein of 64.196 kDa. The DNA sequence of 2908 bp(GenBank Accession No. DQ845248) including five introns was obtained. The fifth intron was uncompleted and complex,including two bases' perfect repeats(GT) 10 and large different-sized repeats within the last 400 bp. The Southern blot hybridization result demonstrated that this gene occurred as a single copy in this species,and the quantitative RT-PCR result showed that the transcription of this gene was constitutive. The evolutional significance of pds was discussed.
文摘A 2 149 bp full length phytoene desaturase (PDS) cDNA was first cloned from saffron (Crocus sativus L.) stigma using RT-PCR technique and a rapid amplification of cDNA end (RACE) strategy. The cDNA has an open reading frame of 1 697 bp, which encodes a polypeptide of 565 amino acids. The coding region of the cDNA was inserted into a prokaryotic expression vector pET-21a(+) and over-expressed inE. coli BL21 (DE3). The fusion proteins were found largely in an insoluble inclusion bodies. The purified fusion protein was used to immunize rabbits to obtain polyclonal antiserum with titer of 1×105. Western blot analysis by using this particular antiserum showed that the higher expression level of PDS in mature stigma than in leaves and stamen, and the higher expression level of PDS in mature stigma than in young stigma. Key words saffron - carotenoids - phytoene desaturase - gene expression - antiserum - Western blot CLC number Q 781 - Q 786 Foundation item: Supported by the Doctoral Foundation of the Ministry of Education, P. R. China and the Young Science Foundation of Sichuan University (Grant 0020405505012)Biography: Bai Jie (1968-), female, Ph. D candidate, research direction: plant developmental biology and reproductive engineering.
文摘Using the mRNA from the fruit of Cara Cara as the template, the cDNA of phytoene synthase （PSY） gene was amplified by reverse transcription polymerse chain reaction （RT-PCR）. Sequence analysis indicated that the cDNA was of 1 520 bp, which had an open reading frame of 1 308 bp and encoded a protein of 436 amino acids. The homology analysis showed that PSY of Cara Cara shared high similarities of nucleotides and deduced amino acids with those in other plants up to more than 75 and 70%, respectively. A putative signal transit peptide for plastid targeting was found in the N-terminal region of PSY. The mature forms of PSY included a transmembrane （TM） domain. The recombinant plasmid pET-CitPSY was constructed by subcloning the full coding sequence of PSY cDNA into pET-28 （＋）. After transformation of E. coli BL21 and induced by 1 mmol L^-1 isopropyl-β-D-thiogalacropyranoside （IPTG）, the fusion protein （6× His-PSY） with 52 kD was produced at a high level by prokaryotic expression system. The results of Western blot demonstrated that the fusion protein （6× His-PSY） could be recognized by anti-6 × His monoclonal antibody. The study could establish a basis for molecular improvement of Citrus fruit colors.
文摘Phytoene synthase （PSY） is the crucial plastidial enzyme in the carotenoid biosynthetic pathway. However, its post-translational regulation remains elusive. Likewise, Clp protease constitutes a central part of the plastid protease network, but its substrates for degradation are not well known. In this study, we report that PSY is a substrate of the Clp protease. PSY was uncovered to physically interact with various Clp protease subunits （i.e., ClpS1, CIpC1, and CIpD）. High levels of PSY and several other carotenogenic enzyme proteins overac- cumulate in the clpcl, clpp4, and clprl-2 mutants. The overaccumulated PSY was found to be partially enzy- matically active. Impairment of Clp activity in clpcl results in a reduced rate of PSY protein turnover, further supporting the role of Clp protease in degrading PSY protein. On the other hand, the ORANGE （OR） protein, a major post-translational regulator of PSY with holdase chaperone activity, enhances PSY protein stability and increases the enzymatically active proportion of PSY in clpcl, counterbalancing CIp-mediated proteol- ysis in maintaining PSY protein homeostasis. Collectively, these findings provide novel insights into the qual- ity control of plastid-localized proteins and establish a hitherto unidentified post-translational regulatory mechanism of carotenogenic enzymes in modulating carotenoid biosynthesis in plants.
基金Thanks for the technical support of Dr.Daqi Fu and Dr.Lanhuan Meng of China Agricultural University.This work was supported by Beijing Municipal Science and Technology Project(Grant No.Z181100002418006)the Fundamental Research Fund for the Central University(Grant No.2015ZCQ-YL-03)the World-Class Discipline Construction and Characteristic Development Guidance Funds for Beijing Forestry University(Grant No.2019XKJS0323).
文摘To understand the functional identification of large-scale genomic sequences in Forsythia,tobacco rattle virus(TRV)-mediated virus-induced gene silencing(VIGS),suitable for the plant,was explored in this study.The results showed that the TRV-mediated VIGS system could be successfully used in Forsythia for silencing the reporter gene FsPDS(Forsythia phytoene desaturase)using stem infiltration and leaf infiltrationmethods.All the treated plants were pruned below the injection site after 7–15 d infection;the FsPDS was silenced and typical photobleaching symptoms were observed in newly sprouted leaves at the whole-plant level.Meanwhile,this system has been successfully tested and verified through virus detection and qRT-PCR analysis.After the optimization,Forsythia magnesium chelatase subunit H(FsChlH)was silenced successfully in Forsythia using this system,resulting in yellow leaveswith decreased chlorophyll content.The system was stable,highly efficient and had greater rapidity and convenience,which made it suitable to study the function of genes related to physiological pathways such as growth and development,and metabolic regulation in Forsythia.
基金supported by grants from the National Natural Science Foundation of China(31000925)the Doctoral Fund of Ministry of Education of China(20110008120019)+1 种基金the Foundation for the Authors of National Excellent Doctoral Dissertations of China(201062)the Basic Research Universities Special Fund Operations(2010JS077)
文摘Eggplant （Solanum melongena） is an economically important vegetable requiring investigation into its various genomic functions. The current limitation in the investigation of genomic function in eggplant is the lack of effective tools available for conducting functional assays. Virus-induced gene silencing （VIGS） has played a critical role in the functional genetic analyses. In this paper, TRV-mediated VIGS was successfully elicited in eggplant. We first cloned the CDS sequence of PDS （PHYTOENE DESATURASE） in eggplant and then silenced the PDS gene. Photo-bleaching was shown on the newly-developed leaves four weeks after agroinoculation, indicating that VIGS can be used to silence genes in eggplant. To further illustrate the reliability of VIGS in eggplant, we selected Chl H, Su and CLA1 as reporters to elicit VIGS using the high-pressure spray method. Suppression of Chl H and Su led to yellow leaves, while the depletion of CLA1 resulted in albino. In conclusion, four genes, PDS, Chl H, Su （Sulfur）, CLA1, were down-regulated significantly by VIGS, indicating that the VIGS system can be successfully applied in eggplant and is a reliable tool for the study of gene function.
文摘The immutans （im） variegation mutant of Arabidopsis defines the gene for PTOX （plastid terminal oxidase）, a versatile plastoquinol oxidase in chloroplast membranes. In this report we used im to gain insight into the function of PTOX in etioplasts of dark-grown seedlings. We discovered that PTOX helps control the redox state of the plastoquinone （PQ） pool in these organelles, and that it plays an essential role in etioplast metabolism by participating in the desaturation reactions of carotenogenesis and in one or more redox pathways mediated by PGR5 （PROTON GRADIENT REGULATION 5） and NDH （NAD（P）H dehydrogenase）, both of which are central players in cyclic electron transport. We propose that these elements couple PTOX with electron flow from NAD（P）H to oxygen, and by analogy to chlororespiration （in chloroplasts） and chromorespiration （in chromoplasts）, we suggest that they define a respiratory process in etioplasts that we have termed ＂etiorespiration＂. We further show that the redox state of the PQ pool in etioplasts might control chlorophyll biosynthesis, perhaps by participating in mechanisms of retrograde （plastid- to-nucleus） signaling that coordinate biosynthetic and photoprotective activities required to poise the etioplast for light development. We conclude that PTOX is an important component of metabolism and redox sensing in etioplasts.
