Plants are capable of regulating their shoot architecture in response to diverse internal and external environments.The circadian clock is an adaptive mechanism that integrates information from internal and ambient co...Plants are capable of regulating their shoot architecture in response to diverse internal and external environments.The circadian clock is an adaptive mechanism that integrates information from internal and ambient conditions to help plants cope with recurring environmental fluctuations.Despite the current understanding of plant circadian clock and genetic framework underlying plant shoot architecture,the intricate connection between these two adaptive mechanisms remains largely unclear.In this study,we elucidated how the core clock gene LUX ARRHYTHMO(LUX)regulates shoot architecture in the model legume plant Medicago truncatula.We show that mtlux mutant displays increased main stem height,reduced lateral shoot length,and decreased the number of lateral branches and biomass yield.Gene expression analysis revealed that Mt LUX regulated shoot architecture by repressing the expression of strigolactone receptor MtD14 and MtTB1/MtTCP1A,a TCP gene that functions centrally in modulating shoot architecture.In vivo and in vitro experiments showed that Mt LUX directly binds to a cis-element in the promoter of MtTB1/MtTCP1A,suggesting that Mt LUX regulates branching by rhythmically suppressing MtTB1/MtTCP1A.This work demonstrates the regulatory effect of the circadian clock on shoot architecture,offering a new understanding underlying the genetic basis towards the flexibility of plant shoot architecture.展开更多
The R2R3-MYB genes make up one of the largest transcription factor families in plants, and play regulatory roles in various biological processes such as development, metabolism and defense response. Although genome-wi...The R2R3-MYB genes make up one of the largest transcription factor families in plants, and play regulatory roles in various biological processes such as development, metabolism and defense response. Although genome-wide analyses of this gene family have been conducted in several species, R2R3-MYB genes have not been systematically analyzed in Medicago truncatula, a sequenced model legume plant. Here, we performed a comprehensive, genome-wide computational analysis of the structural characteristics, phylogeny, functions and expression patterns of M. truncatula R2R3-MYB genes. DNA binding domains are highly conserved among the 155 putative MtR2R3-MYB proteins that we identified. Chromosomal location analysis revealed that these genes were distributed across all eight chromosomes. Results showed that the expansion of the MtR2R3-MYB family was mainly attributable to segmental duplication and tandem duplication. A comprehensive classification was performed based on phylogenetic analysis of the R2R3-MYB gene families in M. truncatula, Arabidopsis thaliana and other plant species. Evolutionary relationships within clades were supported by clade-specific conserved motifs outside the MYB domain. Species-specific clades have been gained or lost during evolution, resulting in functional divergence. Also, tissue-specific expression patterns were investigated. The functions of stress response-related clades were further verified by the changes in transcript levels of representative R2R3-MYB genes upon treatment with abiotic and biotic stresses. This study is the first report on identification and characterization of R2R3-MYB gene family based on the genome of M. truncatula, and will facilitate functional analysis of this gene family in the future.展开更多
Synonymous codon usage pattern presumably reflects gene expression optimization as a result of molecular evolution. Though much attention has been paid to various model organisms ranging from prokaryotes to eukaryotes...Synonymous codon usage pattern presumably reflects gene expression optimization as a result of molecular evolution. Though much attention has been paid to various model organisms ranging from prokaryotes to eukaryotes, codon usage has yet been extensively investigated for model legume Medicago truncatula. In present study, 39 531 available coding sequences （CDSs） from M. truncatula were examined for codon usage bias （CUB）. Based on analyses including neutrality plots, effective number of codons plots, and correlations between optimal codons frequency and codon adaptation index, we conclude that natural selection is a major driving force in M. truncatula CUB. We have identified 30 optimal codons encoding 18 amino acids based on relative synonymous codon usage. These optimal codons characteristically end with A or T, except for AGG and TTG encoding arginine and leucine respectively. Optimal codon usage is positively correlated with the GC content at three nucleotide positions of codons and the GC content of CDSs. The abundance of expressed sequence tag is a proxy for gene expression intensity in the legume, but has no relatedness with either CDS length or GC content. Collectively, we unravel the synonymous codon usage pattern in M. truncatula, which may serve as the valuable information on genetic engineering of the model legume and forage crop.展开更多
Objective: To investigate the potential of anemonin and Clematis flammula(C.flammula) extracts against infective organisms.Methods: The molluscicidal activities of anemonin and C.flammula extracts against Galba trunca...Objective: To investigate the potential of anemonin and Clematis flammula(C.flammula) extracts against infective organisms.Methods: The molluscicidal activities of anemonin and C.flammula extracts against Galba truncatula Mull.(Lymnaeidae) and Fasciola hepatica larval stages contaminating this snail in Tunisia were assessed by testing six groups of snails in 250 mL of extracts and aqueous dechlorinated solutions with different concentrations(ranging from 2.5 to 20.0 mg/L) for 48 h.Besides, the antifungal potential of C.flammula leaves and flowers was evaluated by using the diffusion agar and broth dilution methods against four fungal strains: Aspergillus niger, Pythium catenulatum, Rhizoctonia solani and Fusarium phyllophilum.Results: As a result, hexane and ethyl acetate flower extracts exhibited significant molluscicidal activities with LC_(50) median lethal concentrations values of 11.87 and 11.65 mg/L, respectively while LC_(50) value of anemonin was 9.64 mg/L after 48 h exposure.The flower extracts showed a larvicidal effect with a deterioration rate exceeding 35.39% where flower ethyl acetate residue gave a deterioration rate of cercariae close to 97%.Moreover, C.flammula extracts were not noxious to the associated fauna survival.All extracts inhibited the growth of P.catenulatum, the leaves and flowers methanolic extracts had the more important fungicide action with minimum inhibitory concentrations of 1.56 and 3.12 mg/mL together with minimum fungistatic concentrations of 3.12 and 6.25 mg/mL respectively.Only flower extracts were active against Rhizoctonia solani with minimum inhibitory concentrations varying between 0.70 and 1.56 mg/mL and 6.25 mg/mL of minimum fungistatic concentration.Phytochemical tests showed that the antifungal activity may be attributed to the presence of the flavonoids/saponins in the methanolic extracts and the molluscicide effects could be due to the richness of hexane and ethyl acetate extracts on sterols and triterpenoids.Conclusions: This study emphasizes the important molluscicidal and antiparasitic effects of flower ethyl acetate extracts and anemonin compound as well as the considerable antifungal activities of methanolic extracts.These results improve the therapeutic virtues of C.flammula aerial part extracts.展开更多
Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormo...Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormone.Despite its importance,functions of PSK-αin M.truncatula growth remains unknown.In this study,we identified five genes to encode PSK-αprecursors in M.truncatula.All of these precursors possess conserved PSK-αsignature motif.Expression pattern analysis of these MtPSK genes revealed that each gene was expressed in a tissue-specific or ubiquitous pattern and three of them were remarkably expressed in root.Treatment of M.truncatula seedlings with synthetic PSK-αpeptide significantly promoted root elongation.In addition,expression analysis of downstream genes by RNA-seq and qRT-PCR assays suggested that PSK-αsignaling might regulate cell wall structure via PMEI-PME module to promote root cell growth.Taken together,our results shed light on the mechanism by which PSK-αpromotes root growth in M.truncatula,providing a new resource for improvement of root growth in agriculture.展开更多
MicroRNAs(miRNAs)是一类内源性非编码小分子RNA,参与调控植物的生长发育、代谢和逆境响应等过程。本研究通过构建蒺藜苜蓿miR167c的海绵载体,探究miR167c及其靶基因对拟南芥生长发育的影响。靶基因预测结果显示,生长素响应因子6/8(Auxi...MicroRNAs(miRNAs)是一类内源性非编码小分子RNA,参与调控植物的生长发育、代谢和逆境响应等过程。本研究通过构建蒺藜苜蓿miR167c的海绵载体,探究miR167c及其靶基因对拟南芥生长发育的影响。靶基因预测结果显示,生长素响应因子6/8(Auxin response factor 6/8,ARF6/8)、类受体蛋白激酶家族蛋白(Receptor-like protein kinase-related family protein,RPK)和IAA-氨基酸水解酶(IAA-Alanine resistant 3,IAR3)基因为拟南芥miR167c的靶基因。实时荧光定量分析表明,转基因拟南芥植株中At-miR167c表达量较野生型显著降低,而上述4个靶基因的表达量显著上调。转基因拟南芥的花期提前,花序紧凑,花苞数量增多;莲座叶数量和鲜重显著增加;株高、分枝数和果荚数明显增加。研究结果为进一步解析miR167调控植物生长和花器官发育的分子机制提供了参考依据。展开更多
本文对蒺藜苜蓿叶绿体基因组全序列密码子进行分析，筛选出50条CDS（coding DNA sequence）利用Codo-nW软件进行分析其密码子使用模式。结果显示，蒺藜苜蓿叶绿体基因组密码子第3位碱基GC含量为26．9％，即第3位密码子富含A和U，ENC值...本文对蒺藜苜蓿叶绿体基因组全序列密码子进行分析，筛选出50条CDS（coding DNA sequence）利用Codo-nW软件进行分析其密码子使用模式。结果显示，蒺藜苜蓿叶绿体基因组密码子第3位碱基GC含量为26．9％，即第3位密码子富含A和U，ENC值在37．11～51．91之间密码子偏好性较弱。相对同义密码子使用度分析显示RSCU值大于1的密码子有23个，其中以A和U为结尾20个。中性绘图分析显示GC12与GC3的相关系数为0．341，相关性不显著，回归系数为0．4843；单基因ENC比值多分布在-0．05～0．05，即大部分基因ENC值离ENC期望值较近；对应性分析，第一轴显示了12．50％的差异为主要影响因素，第一轴与ENC和GC。的相关系数分别为0．091和-0．092，均相关不显著。综合这几项分析发现蒺藜苜蓿叶绿体基因组密码子偏好性主要受到突变的影响，但是并不是唯一的影响因素，其他因素对密码子偏好性也可能有一定的影响。最终通过高表达优越密码子方法确定得出UUA、UUG、CCU等23个密码子为最优密码子，为之后对外源基因进行改造，提高其在叶绿体中的表达效率奠定了基础。展开更多
基金supported by Laboratory of Lingnan Modern Agriculture Project(NZ2021001)State Key Laboratory for Conservation and Utilization of Subtropical Agrobioresources(SKICUSA-a202007)Natural Science Foundation of Guangdong Province(2022A1515011027,2019A1515012009)。
文摘Plants are capable of regulating their shoot architecture in response to diverse internal and external environments.The circadian clock is an adaptive mechanism that integrates information from internal and ambient conditions to help plants cope with recurring environmental fluctuations.Despite the current understanding of plant circadian clock and genetic framework underlying plant shoot architecture,the intricate connection between these two adaptive mechanisms remains largely unclear.In this study,we elucidated how the core clock gene LUX ARRHYTHMO(LUX)regulates shoot architecture in the model legume plant Medicago truncatula.We show that mtlux mutant displays increased main stem height,reduced lateral shoot length,and decreased the number of lateral branches and biomass yield.Gene expression analysis revealed that Mt LUX regulated shoot architecture by repressing the expression of strigolactone receptor MtD14 and MtTB1/MtTCP1A,a TCP gene that functions centrally in modulating shoot architecture.In vivo and in vitro experiments showed that Mt LUX directly binds to a cis-element in the promoter of MtTB1/MtTCP1A,suggesting that Mt LUX regulates branching by rhythmically suppressing MtTB1/MtTCP1A.This work demonstrates the regulatory effect of the circadian clock on shoot architecture,offering a new understanding underlying the genetic basis towards the flexibility of plant shoot architecture.
基金supported by the National Natural Science Foundation of China(31372362)
文摘The R2R3-MYB genes make up one of the largest transcription factor families in plants, and play regulatory roles in various biological processes such as development, metabolism and defense response. Although genome-wide analyses of this gene family have been conducted in several species, R2R3-MYB genes have not been systematically analyzed in Medicago truncatula, a sequenced model legume plant. Here, we performed a comprehensive, genome-wide computational analysis of the structural characteristics, phylogeny, functions and expression patterns of M. truncatula R2R3-MYB genes. DNA binding domains are highly conserved among the 155 putative MtR2R3-MYB proteins that we identified. Chromosomal location analysis revealed that these genes were distributed across all eight chromosomes. Results showed that the expansion of the MtR2R3-MYB family was mainly attributable to segmental duplication and tandem duplication. A comprehensive classification was performed based on phylogenetic analysis of the R2R3-MYB gene families in M. truncatula, Arabidopsis thaliana and other plant species. Evolutionary relationships within clades were supported by clade-specific conserved motifs outside the MYB domain. Species-specific clades have been gained or lost during evolution, resulting in functional divergence. Also, tissue-specific expression patterns were investigated. The functions of stress response-related clades were further verified by the changes in transcript levels of representative R2R3-MYB genes upon treatment with abiotic and biotic stresses. This study is the first report on identification and characterization of R2R3-MYB gene family based on the genome of M. truncatula, and will facilitate functional analysis of this gene family in the future.
基金supported by the National Basic Research Program of China (2014CB138702)the National Natural Science Foundation of China (31502001)
文摘Synonymous codon usage pattern presumably reflects gene expression optimization as a result of molecular evolution. Though much attention has been paid to various model organisms ranging from prokaryotes to eukaryotes, codon usage has yet been extensively investigated for model legume Medicago truncatula. In present study, 39 531 available coding sequences （CDSs） from M. truncatula were examined for codon usage bias （CUB）. Based on analyses including neutrality plots, effective number of codons plots, and correlations between optimal codons frequency and codon adaptation index, we conclude that natural selection is a major driving force in M. truncatula CUB. We have identified 30 optimal codons encoding 18 amino acids based on relative synonymous codon usage. These optimal codons characteristically end with A or T, except for AGG and TTG encoding arginine and leucine respectively. Optimal codon usage is positively correlated with the GC content at three nucleotide positions of codons and the GC content of CDSs. The abundance of expressed sequence tag is a proxy for gene expression intensity in the legume, but has no relatedness with either CDS length or GC content. Collectively, we unravel the synonymous codon usage pattern in M. truncatula, which may serve as the valuable information on genetic engineering of the model legume and forage crop.
基金supported by the Tunisian National Ministry of Higher Education and Scientific Research
文摘Objective: To investigate the potential of anemonin and Clematis flammula(C.flammula) extracts against infective organisms.Methods: The molluscicidal activities of anemonin and C.flammula extracts against Galba truncatula Mull.(Lymnaeidae) and Fasciola hepatica larval stages contaminating this snail in Tunisia were assessed by testing six groups of snails in 250 mL of extracts and aqueous dechlorinated solutions with different concentrations(ranging from 2.5 to 20.0 mg/L) for 48 h.Besides, the antifungal potential of C.flammula leaves and flowers was evaluated by using the diffusion agar and broth dilution methods against four fungal strains: Aspergillus niger, Pythium catenulatum, Rhizoctonia solani and Fusarium phyllophilum.Results: As a result, hexane and ethyl acetate flower extracts exhibited significant molluscicidal activities with LC_(50) median lethal concentrations values of 11.87 and 11.65 mg/L, respectively while LC_(50) value of anemonin was 9.64 mg/L after 48 h exposure.The flower extracts showed a larvicidal effect with a deterioration rate exceeding 35.39% where flower ethyl acetate residue gave a deterioration rate of cercariae close to 97%.Moreover, C.flammula extracts were not noxious to the associated fauna survival.All extracts inhibited the growth of P.catenulatum, the leaves and flowers methanolic extracts had the more important fungicide action with minimum inhibitory concentrations of 1.56 and 3.12 mg/mL together with minimum fungistatic concentrations of 3.12 and 6.25 mg/mL respectively.Only flower extracts were active against Rhizoctonia solani with minimum inhibitory concentrations varying between 0.70 and 1.56 mg/mL and 6.25 mg/mL of minimum fungistatic concentration.Phytochemical tests showed that the antifungal activity may be attributed to the presence of the flavonoids/saponins in the methanolic extracts and the molluscicide effects could be due to the richness of hexane and ethyl acetate extracts on sterols and triterpenoids.Conclusions: This study emphasizes the important molluscicidal and antiparasitic effects of flower ethyl acetate extracts and anemonin compound as well as the considerable antifungal activities of methanolic extracts.These results improve the therapeutic virtues of C.flammula aerial part extracts.
基金This work is supported by the National Natural Science Foundation of China(31500197).
文摘Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormone.Despite its importance,functions of PSK-αin M.truncatula growth remains unknown.In this study,we identified five genes to encode PSK-αprecursors in M.truncatula.All of these precursors possess conserved PSK-αsignature motif.Expression pattern analysis of these MtPSK genes revealed that each gene was expressed in a tissue-specific or ubiquitous pattern and three of them were remarkably expressed in root.Treatment of M.truncatula seedlings with synthetic PSK-αpeptide significantly promoted root elongation.In addition,expression analysis of downstream genes by RNA-seq and qRT-PCR assays suggested that PSK-αsignaling might regulate cell wall structure via PMEI-PME module to promote root cell growth.Taken together,our results shed light on the mechanism by which PSK-αpromotes root growth in M.truncatula,providing a new resource for improvement of root growth in agriculture.
文摘MicroRNAs(miRNAs)是一类内源性非编码小分子RNA,参与调控植物的生长发育、代谢和逆境响应等过程。本研究通过构建蒺藜苜蓿miR167c的海绵载体,探究miR167c及其靶基因对拟南芥生长发育的影响。靶基因预测结果显示,生长素响应因子6/8(Auxin response factor 6/8,ARF6/8)、类受体蛋白激酶家族蛋白(Receptor-like protein kinase-related family protein,RPK)和IAA-氨基酸水解酶(IAA-Alanine resistant 3,IAR3)基因为拟南芥miR167c的靶基因。实时荧光定量分析表明,转基因拟南芥植株中At-miR167c表达量较野生型显著降低,而上述4个靶基因的表达量显著上调。转基因拟南芥的花期提前,花序紧凑,花苞数量增多;莲座叶数量和鲜重显著增加;株高、分枝数和果荚数明显增加。研究结果为进一步解析miR167调控植物生长和花器官发育的分子机制提供了参考依据。
文摘本文对蒺藜苜蓿叶绿体基因组全序列密码子进行分析，筛选出50条CDS（coding DNA sequence）利用Codo-nW软件进行分析其密码子使用模式。结果显示，蒺藜苜蓿叶绿体基因组密码子第3位碱基GC含量为26．9％，即第3位密码子富含A和U，ENC值在37．11～51．91之间密码子偏好性较弱。相对同义密码子使用度分析显示RSCU值大于1的密码子有23个，其中以A和U为结尾20个。中性绘图分析显示GC12与GC3的相关系数为0．341，相关性不显著，回归系数为0．4843；单基因ENC比值多分布在-0．05～0．05，即大部分基因ENC值离ENC期望值较近；对应性分析，第一轴显示了12．50％的差异为主要影响因素，第一轴与ENC和GC。的相关系数分别为0．091和-0．092，均相关不显著。综合这几项分析发现蒺藜苜蓿叶绿体基因组密码子偏好性主要受到突变的影响，但是并不是唯一的影响因素，其他因素对密码子偏好性也可能有一定的影响。最终通过高表达优越密码子方法确定得出UUA、UUG、CCU等23个密码子为最优密码子，为之后对外源基因进行改造，提高其在叶绿体中的表达效率奠定了基础。
