SWEET(sugars will eventually be exported transporters)基因广泛存在于植物、动物和微生物中,在细胞膜或者细胞器膜形成跨膜孔道,协助糖类物质完成跨膜运输。拟南芥SWEET1/2/3基因属于SWEET基因家族CladeⅠ分支。通过表达谱数据分析...SWEET(sugars will eventually be exported transporters)基因广泛存在于植物、动物和微生物中,在细胞膜或者细胞器膜形成跨膜孔道,协助糖类物质完成跨膜运输。拟南芥SWEET1/2/3基因属于SWEET基因家族CladeⅠ分支。通过表达谱数据分析发现,SWEET1基因在花器官优先表达,SWEET2基因在营养生长和生殖生长期均有表达,SWEET3基因在花中表达。三个基因在体外鉴定具有葡萄糖转运活性,但由于缺少功能缺失的突变体和功能冗余,它们的生理功能仍不清楚。通过CRISPR/Cas9系统在SWEET1/2/3基因中创建了靶向突变,鉴定获得了sweet1、sweet1/2、sweet3和sweet1/2/3突变体。突变体在营养生长过程中表型与野生型相同,但它们的角果长度显著短于野生型的角果。在高浓度葡萄糖培养基上,sweet1、sweet1/2和sweet1/2/3突变体对葡萄糖敏感,其特征是根更短,高度严重降低,表明SWEET1/2/3基因在葡萄糖信号中具有功能。对葡萄糖信号通路中关键基因的进一步分析发现,HXK1、KIN10和KIN11在野生型和突变体之间转录和翻译水平没有显著差异。结果表明,拟南芥SWEET1/2/3基因在葡萄糖信号传导和调节角果的发育中起着重要作用。展开更多
Plant growth and development are significantly hampered in saline environments,limiting agricultural productivity.Thus,it is crucial to unravel the mechanism underlying plant responses to salt stress.β-1,4-Galactan(g...Plant growth and development are significantly hampered in saline environments,limiting agricultural productivity.Thus,it is crucial to unravel the mechanism underlying plant responses to salt stress.β-1,4-Galactan(galactan),which forms the side chains of pectic rhamnogalacturonan I,enhances plant sensitivity to high-salt stress.Galactan is synthesized by GALACTAN SYNTHASE1(GALS1).We previously showed that Na Cl relieves the direct suppression of GALS1 transcription by the transcription factors BPC1 and BPC2 to induce the excess accumulation of galactan in Arabidopsis(Arabidopsis thaliana).However,how plants adapt to this unfavorable environment remains unclear.Here,we determined that the transcription factors CBF1,CBF2,and CBF3 directly interact with the GALS1 promoter and repress its expression,leading to reduced galactan accumulation and enhanced salt tolerance.Salt stress enhances the binding of CBF1/CBF2/CBF3 to the GALS1 promoter by inducing CBF1/CBF2/CBF3 transcription and accumulation.Genetic analysis suggested that CBF1/CBF2/CBF3 function upstream of GALS1 to modulate salt-induced galactan biosynthesis and the salt response.CBF1/CBF2/CBF3 and BPC1/BPC2 function in parallel to regulate GALS1 expression,thereby modulating the salt response.Our results reveal a mechanism in which salt-activated CBF1/CBF2/CBF3 inhibit BPC1/BPC2-regulated GALS1 expression to alleviate galactan-induced salt hypersensitivity,providing an activation/deactivation fine-tune mechanism for dynamic regulation of GALS1 expression under salt stress in Arabidopsis.展开更多
Mitogen activated protein kinase kinase kinase 18(MAPKKK18)mediated signaling cascade plays important roles in Arabidopsis drought stress tolerance.However,the post-translational modulation patterns of MAPKKK18 are no...Mitogen activated protein kinase kinase kinase 18(MAPKKK18)mediated signaling cascade plays important roles in Arabidopsis drought stress tolerance.However,the post-translational modulation patterns of MAPKKK18 are not characterized.In this study,we found that the protein level of MAPKKK18 was tightly controlled by the 26 S proteasome.Ubiquitin ligases RGLG1 and RGLG2 ubiquitinated MAPKKK18 at lysine residue K32 and K154,and promoted its degradation.Deletion of RGLG1 and RGLG2 stabilized MAPKKK18 and further enhanced the drought stress tolerance of MAPKKK18-overexpression plants.Our data demonstrate that RGLG1 and RGLG2 negatively regulate MAPKKK18-mediated drought stress tolerance in Arabidopsis.展开更多
Indole-3-acetamide(IAM)is the first confirmed auxin biosynthetic intermediate in some plant pathogenic bacteria.Exogenously applied IAM or production of IAM by overexpressing the bacterial iaaM gene in Arabidopsis cau...Indole-3-acetamide(IAM)is the first confirmed auxin biosynthetic intermediate in some plant pathogenic bacteria.Exogenously applied IAM or production of IAM by overexpressing the bacterial iaaM gene in Arabidopsis causes auxin overproduction phenotypes.However,it is still inconclusive whether plants use IAM as a key precursor for auxin biosynthesis.Herein,we reported the isolation IAM HYDROLASE 1(IAMH1)gene in Arabidopsis from a forward genetic screen for IAM-insensitive mutants that display normal auxin sensitivities.IAMH1 has a close homolog named IAMH2 that is located right next to IAMH1on chromosomeⅣin Arabidopsis.We generated iamh1 iamh2 double mutants using our CRISPR/Cas9gene editing technology.We showed that disruption of the IAMH genes rendered Arabidopsis plants resistant to IAM treatments and also suppressed the iaaM overexpression phenotypes,suggesting that IAMH1 and IAMH2 are the main enzymes responsible for converting IAM into indole-3-acetic acid(IAA)in Arabidopsis.The iamh double mutants did not display obvious developmental defects,indicating that IAM does not play a major role in auxin biosynthesis under normal growth conditions.Our findings provide a solid foundation for clarifying the roles of IAM in auxin biosynthesis and plant development.展开更多
The mitotic activity of root apical meristem(RAM)is critical to primary root growth and development.Previous studies have identified the roles of ROOT GROWTH FACTOR 1(RGF1),a peptide ligand,and its receptors,RGF1 INSE...The mitotic activity of root apical meristem(RAM)is critical to primary root growth and development.Previous studies have identified the roles of ROOT GROWTH FACTOR 1(RGF1),a peptide ligand,and its receptors,RGF1 INSENSITIVEs(RGIs),a clade of five leucine-rich-repeat receptor-like kinases,in promoting cell division in the RAM,which determines the primary root length.However,the downstream signaling components remain elusive.In this study,we identify a complete mitogen-activated protein kinase(MAPK or MPK)cascade,composed of YDA,MKK4/MKK5,and MPK3/MPK6,that functions downstream of the RGF1-RGI ligand-receptor pair.Similar to the rgi1/2/3/4/5 quintuple mutant,loss-of-function mutants of MPK3 and MPK6,MKK4 and MKK5,or YDA show a short-root phenotype,which is associated with reduced mitotic activity and lower expression of PLETHORA 1(PLT1)/PLT2 in the RAM.Furthermore,MPK3/MPK6 activation in response to exogenous RGF1 treatment is impaired in the rgi1/2/3/4/5 quintuple,yda single,and mkk4 m kk5 double mutants.Epistatic analyses demonstrated that the expression of constitutively active MKK4,MKK5,or YDA driven by the RGI2 promoter can rescue the short-root phenotype of the rgi1/2/3/4/5 mutant.Taken together,these results suggest that the YDA-MKK4/MKK5-MPK3/MPK6 cascade functions downstream of the RGF1-RGI ligand-receptor pair and upstream of PLT1/PLT2 to modulate the stem cell population and primary root growth in Arabidopsis.展开更多
Polycomb-group （Pc-G） proteins repress their target gene expression by assemble complexes in Drosophila and mammals. Three groups of Pc-G genes, controlling seed development, flower development and vernalization res...Polycomb-group （Pc-G） proteins repress their target gene expression by assemble complexes in Drosophila and mammals. Three groups of Pc-G genes, controlling seed development, flower development and vernalization response, have been identified in Arabidopsis （Arabidopsis thaliana L.）. MEDEA （MEA）, FERTILIZATION INDEPENDENT SEED2 （FIS2）, and FERTILIZATION INDEPENDENT ENDOSPERM （FIE） are Pc-G genes in Arabidopsis. Their functions in seed development have been extensively explored. The advanced findings of molecular mechanism on how MEA, FIS2 and FIE control seed development in Arabidopsis are reviewed in this paper.展开更多
Unlike animals,plant development is plastic and sensitive to environmental changes.For example,Arabidopsis thaliana seedlings display distinct growth patterns when they are grown under different light or temperature c...Unlike animals,plant development is plastic and sensitive to environmental changes.For example,Arabidopsis thaliana seedlings display distinct growth patterns when they are grown under different light or temperature conditions.M oreover,endogenous plant hormone such as ethylene also impacts seedling morphol ogy.Ethylene induces hypocotyl elongation in light-grown seedlings but strongly inhibits hypocotyl elongation in etiolated(dark-grown)seedlings.Another characteristic ethylene response in etiolated seedlings is the formation of exaggerated apical hooks.Although it is well known that high ambient temperature promotes hypocotyl elongation in light-grown seedlings(thermomor-phogenesis),ethylene suppresses thermomorphogenesis.On another side,high ambient temperature also inhibits the ethylene-responsive hypocotyl shortening and exaggerated hook for mation in etiolated seedlings.Therefore,the simplest phytohormone ethylene exhibits almost the most complicated responses,depending on temperature and/or light conditions.In this review,we will focus on two topics related to the main theme of this special issue(response to high temperature):(1)how does high temperature suppress ethylene-induced seedling morphology in dark grown seedlings,and(2)how does ethylene inhibit high temperature-induced seedling growth in light-grown seedlings.Controlling ethylene biosynthesis through antisense technology was the hallmark event in plant genetic engi-neering in 1990,we assume that manipulations on plant ethylene signaling in agricultural plants may pave the way for coping with climate change in future.展开更多
文摘SWEET(sugars will eventually be exported transporters)基因广泛存在于植物、动物和微生物中,在细胞膜或者细胞器膜形成跨膜孔道,协助糖类物质完成跨膜运输。拟南芥SWEET1/2/3基因属于SWEET基因家族CladeⅠ分支。通过表达谱数据分析发现,SWEET1基因在花器官优先表达,SWEET2基因在营养生长和生殖生长期均有表达,SWEET3基因在花中表达。三个基因在体外鉴定具有葡萄糖转运活性,但由于缺少功能缺失的突变体和功能冗余,它们的生理功能仍不清楚。通过CRISPR/Cas9系统在SWEET1/2/3基因中创建了靶向突变,鉴定获得了sweet1、sweet1/2、sweet3和sweet1/2/3突变体。突变体在营养生长过程中表型与野生型相同,但它们的角果长度显著短于野生型的角果。在高浓度葡萄糖培养基上,sweet1、sweet1/2和sweet1/2/3突变体对葡萄糖敏感,其特征是根更短,高度严重降低,表明SWEET1/2/3基因在葡萄糖信号中具有功能。对葡萄糖信号通路中关键基因的进一步分析发现,HXK1、KIN10和KIN11在野生型和突变体之间转录和翻译水平没有显著差异。结果表明,拟南芥SWEET1/2/3基因在葡萄糖信号传导和调节角果的发育中起着重要作用。
基金supported by grants from the National Natural Science Foundation of China(32001445)。
文摘Plant growth and development are significantly hampered in saline environments,limiting agricultural productivity.Thus,it is crucial to unravel the mechanism underlying plant responses to salt stress.β-1,4-Galactan(galactan),which forms the side chains of pectic rhamnogalacturonan I,enhances plant sensitivity to high-salt stress.Galactan is synthesized by GALACTAN SYNTHASE1(GALS1).We previously showed that Na Cl relieves the direct suppression of GALS1 transcription by the transcription factors BPC1 and BPC2 to induce the excess accumulation of galactan in Arabidopsis(Arabidopsis thaliana).However,how plants adapt to this unfavorable environment remains unclear.Here,we determined that the transcription factors CBF1,CBF2,and CBF3 directly interact with the GALS1 promoter and repress its expression,leading to reduced galactan accumulation and enhanced salt tolerance.Salt stress enhances the binding of CBF1/CBF2/CBF3 to the GALS1 promoter by inducing CBF1/CBF2/CBF3 transcription and accumulation.Genetic analysis suggested that CBF1/CBF2/CBF3 function upstream of GALS1 to modulate salt-induced galactan biosynthesis and the salt response.CBF1/CBF2/CBF3 and BPC1/BPC2 function in parallel to regulate GALS1 expression,thereby modulating the salt response.Our results reveal a mechanism in which salt-activated CBF1/CBF2/CBF3 inhibit BPC1/BPC2-regulated GALS1 expression to alleviate galactan-induced salt hypersensitivity,providing an activation/deactivation fine-tune mechanism for dynamic regulation of GALS1 expression under salt stress in Arabidopsis.
基金supported by the National Natural Science Foundation of China(31771878 and 31901752)the Major Program of Shandong Province Natural Science Foundation(ZR2018ZB0212)。
文摘Mitogen activated protein kinase kinase kinase 18(MAPKKK18)mediated signaling cascade plays important roles in Arabidopsis drought stress tolerance.However,the post-translational modulation patterns of MAPKKK18 are not characterized.In this study,we found that the protein level of MAPKKK18 was tightly controlled by the 26 S proteasome.Ubiquitin ligases RGLG1 and RGLG2 ubiquitinated MAPKKK18 at lysine residue K32 and K154,and promoted its degradation.Deletion of RGLG1 and RGLG2 stabilized MAPKKK18 and further enhanced the drought stress tolerance of MAPKKK18-overexpression plants.Our data demonstrate that RGLG1 and RGLG2 negatively regulate MAPKKK18-mediated drought stress tolerance in Arabidopsis.
文摘Indole-3-acetamide(IAM)is the first confirmed auxin biosynthetic intermediate in some plant pathogenic bacteria.Exogenously applied IAM or production of IAM by overexpressing the bacterial iaaM gene in Arabidopsis causes auxin overproduction phenotypes.However,it is still inconclusive whether plants use IAM as a key precursor for auxin biosynthesis.Herein,we reported the isolation IAM HYDROLASE 1(IAMH1)gene in Arabidopsis from a forward genetic screen for IAM-insensitive mutants that display normal auxin sensitivities.IAMH1 has a close homolog named IAMH2 that is located right next to IAMH1on chromosomeⅣin Arabidopsis.We generated iamh1 iamh2 double mutants using our CRISPR/Cas9gene editing technology.We showed that disruption of the IAMH genes rendered Arabidopsis plants resistant to IAM treatments and also suppressed the iaaM overexpression phenotypes,suggesting that IAMH1 and IAMH2 are the main enzymes responsible for converting IAM into indole-3-acetic acid(IAA)in Arabidopsis.The iamh double mutants did not display obvious developmental defects,indicating that IAM does not play a major role in auxin biosynthesis under normal growth conditions.Our findings provide a solid foundation for clarifying the roles of IAM in auxin biosynthesis and plant development.
基金grants from the National Natural Science Foundation of China(31922005)the Natural Science Foundation of Zhejiang Province(LR18C020001)+1 种基金the Young Elite Scientist Sponsorship Program of China Association for Science and Technology(CAST)(2018QNRC001)111 Project(B14027)to J.X.
文摘The mitotic activity of root apical meristem(RAM)is critical to primary root growth and development.Previous studies have identified the roles of ROOT GROWTH FACTOR 1(RGF1),a peptide ligand,and its receptors,RGF1 INSENSITIVEs(RGIs),a clade of five leucine-rich-repeat receptor-like kinases,in promoting cell division in the RAM,which determines the primary root length.However,the downstream signaling components remain elusive.In this study,we identify a complete mitogen-activated protein kinase(MAPK or MPK)cascade,composed of YDA,MKK4/MKK5,and MPK3/MPK6,that functions downstream of the RGF1-RGI ligand-receptor pair.Similar to the rgi1/2/3/4/5 quintuple mutant,loss-of-function mutants of MPK3 and MPK6,MKK4 and MKK5,or YDA show a short-root phenotype,which is associated with reduced mitotic activity and lower expression of PLETHORA 1(PLT1)/PLT2 in the RAM.Furthermore,MPK3/MPK6 activation in response to exogenous RGF1 treatment is impaired in the rgi1/2/3/4/5 quintuple,yda single,and mkk4 m kk5 double mutants.Epistatic analyses demonstrated that the expression of constitutively active MKK4,MKK5,or YDA driven by the RGI2 promoter can rescue the short-root phenotype of the rgi1/2/3/4/5 mutant.Taken together,these results suggest that the YDA-MKK4/MKK5-MPK3/MPK6 cascade functions downstream of the RGF1-RGI ligand-receptor pair and upstream of PLT1/PLT2 to modulate the stem cell population and primary root growth in Arabidopsis.
基金Publication of this paper is supported by the National Natural Science Foundation of China （30624808） and Science Publication Foundation of the Chinese Academy of Sciences.
文摘Polycomb-group （Pc-G） proteins repress their target gene expression by assemble complexes in Drosophila and mammals. Three groups of Pc-G genes, controlling seed development, flower development and vernalization response, have been identified in Arabidopsis （Arabidopsis thaliana L.）. MEDEA （MEA）, FERTILIZATION INDEPENDENT SEED2 （FIS2）, and FERTILIZATION INDEPENDENT ENDOSPERM （FIE） are Pc-G genes in Arabidopsis. Their functions in seed development have been extensively explored. The advanced findings of molecular mechanism on how MEA, FIS2 and FIE control seed development in Arabidopsis are reviewed in this paper.
基金the National Natural Science Foundation of China(31970256)the Natural Science Foundation of jiangsu Province(BK20201371)the Qing Lan Project and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Unlike animals,plant development is plastic and sensitive to environmental changes.For example,Arabidopsis thaliana seedlings display distinct growth patterns when they are grown under different light or temperature conditions.M oreover,endogenous plant hormone such as ethylene also impacts seedling morphol ogy.Ethylene induces hypocotyl elongation in light-grown seedlings but strongly inhibits hypocotyl elongation in etiolated(dark-grown)seedlings.Another characteristic ethylene response in etiolated seedlings is the formation of exaggerated apical hooks.Although it is well known that high ambient temperature promotes hypocotyl elongation in light-grown seedlings(thermomor-phogenesis),ethylene suppresses thermomorphogenesis.On another side,high ambient temperature also inhibits the ethylene-responsive hypocotyl shortening and exaggerated hook for mation in etiolated seedlings.Therefore,the simplest phytohormone ethylene exhibits almost the most complicated responses,depending on temperature and/or light conditions.In this review,we will focus on two topics related to the main theme of this special issue(response to high temperature):(1)how does high temperature suppress ethylene-induced seedling morphology in dark grown seedlings,and(2)how does ethylene inhibit high temperature-induced seedling growth in light-grown seedlings.Controlling ethylene biosynthesis through antisense technology was the hallmark event in plant genetic engi-neering in 1990,we assume that manipulations on plant ethylene signaling in agricultural plants may pave the way for coping with climate change in future.
