The maintenance of stem cells within the root meristem is the foundation for the continuous growth of the root system.The PLETHORA(PLT)transcription factors control root meristem patterning,but the underlying molecula...The maintenance of stem cells within the root meristem is the foundation for the continuous growth of the root system.The PLETHORA(PLT)transcription factors control root meristem patterning,but the underlying molecular mechanism remains unclear.In this study,we show that rice PLT3,PLT4,and PLT5 promote a repressive chromatin state to maintain stem cell fate in the root meristem.We demonstrated that PLT5 interacts with Polycomb repressive complex 2(PRC2),which deposits the repressive mark H3K27me3,and the histone demethylase JMJ703,which removes the active mark H3K4me3 in rice root meristem cells.In addition,JMJ703 itself associates with PRC2 proteins.We found that loss of PLT3,PLT4,and PLT5 function results in decreased PRC2 association H3K27me3,increased H3K4me3,and upregulated expression of genes decorated with the two marks in the root meristem.Further analyses revealed that PLT interactions with PRC2 and JMJ703 enhance the H3K27me3/H3K4me3 ratio at a set of bivalent genes,thereby maintaining their silent state.Taken together,these results uncover a chromatin mechanism by which PLTs control the stem cell fate in the rice root meristem.展开更多
Conserved non-coding sequences(CNSs)are integral elements of transcriptional regulation.Transcriptional tuning of PLETHORA(PLT)genes that encode master regulators of plant development is vital for embryogenesis and me...Conserved non-coding sequences(CNSs)are integral elements of transcriptional regulation.Transcriptional tuning of PLETHORA(PLT)genes that encode master regulators of plant development is vital for embryogenesis and meristematic function.However,how the expression of PLT genes is modulated through CNSs remains unclear.Through motif-based mining of upstream sequences in 120 angiosperm ge-nomes,we identified 21 conserved and lineage-specific CNSs,two of which are unusually long,similar,and colinear within eudicots.Using Arabidopsis thaliana,we demonstrate that these two deeply conserved elements,which we named BOX1 and BOX2,control PLT1 and PLT2 expression.CRISPR mutants within these elements specifically reduced PLT expression levels,and reporter lines revealed that deletion of either or both BOXes altered and/or abrogated the PLT2 expression pattern in the root tip,affecting the abil-ity to rescue the plt1 plt2 double mutant.We further show that the influence of these elements on expres-sion patterns is already exerted during embryogenesis and functional in the context of the early embryo.Finally,we reveal the existence of a BOX-mediated autoregulatory feedback loop that,in large part,explains CNS influence on expression patterns.Wethus uncover a transcriptional mechanism by which genes encoding master regulators of embryo and root meristem development are regulated.展开更多
L-Cysteine plays a prominent role in sulfur metabo- lism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. E...L-Cysteine plays a prominent role in sulfur metabo- lism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PiNs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and 5CR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth.展开更多
A plethora of studies suggest that the non-transformed cellularand non-ceHular comp on ents of the tumor,collectively known as the tumor microenvironment,have a significa nt impact on the tumorigenic process.It was su...A plethora of studies suggest that the non-transformed cellularand non-ceHular comp on ents of the tumor,collectively known as the tumor microenvironment,have a significa nt impact on the tumorigenic process.It was suggested that the microenvironment,which initially restricts tumor development,is recruited by the tumor and main tains a crosstalk that further promotes cancer progression.展开更多
Pre-mRNA(messenger RNA)splicing participates in the regulation of numerous biological processes in plants.For example,alternative splicing shapes transcriptomic responses to abiotic and biotic stress,and controls deve...Pre-mRNA(messenger RNA)splicing participates in the regulation of numerous biological processes in plants.For example,alternative splicing shapes transcriptomic responses to abiotic and biotic stress,and controls developmental programs.However,no study has revealed a role for splicing in maintaining the root stem cell niche.Here,a screen for defects in root growth in Arabidopsis thaliana identified an ethyl methane sulfonate mutant defective in pre-m RNA splicing(rdm16-4).The rdm16-4 mutant displays a short-root phenotype resulting from fewer cells in the root apical meristem.The PLETHORA1(PLT1)and PLT2 transcription factor genes are important for root development and were alternatively spliced in rdm16-4 mutants,resulting in a disordered root stem cell niche and retarded root growth.The root cap of rdm16-4 contained reduced levels of cytokinins,which promote differentiation in the developing root.This reduction was associated with the alternative splicing of genes encoding cytokinin signaling factors,such as ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN5 and ARABIDOPSIS RESPONSE REGULATORS(ARR1,ARR2,and ARR11).Furthermore,expression of the full-length coding sequence of ARR1 or exogenous cytokinin application partially rescued the short-root phenotype of rdm16-4.This reveals that the RDM16-mediated alternative splicing of cytokinin signaling components contributes to root growth.展开更多
基金supported by National Natural Science Foundation of China(324700359 and 32470307)the Fundamental Research Funds for the Central Universities,China(2016RC003,2662025SKPY002,and 2662015PY228)+2 种基金the Fundamental Research Program of Hubei Province(2024AFE001)the Earmarked Fund for China Agriculture Research System(No.CARS-01)Fujian Provincial Middle-aged and Young Teachers Education Research Project(JAT241023).
文摘The maintenance of stem cells within the root meristem is the foundation for the continuous growth of the root system.The PLETHORA(PLT)transcription factors control root meristem patterning,but the underlying molecular mechanism remains unclear.In this study,we show that rice PLT3,PLT4,and PLT5 promote a repressive chromatin state to maintain stem cell fate in the root meristem.We demonstrated that PLT5 interacts with Polycomb repressive complex 2(PRC2),which deposits the repressive mark H3K27me3,and the histone demethylase JMJ703,which removes the active mark H3K4me3 in rice root meristem cells.In addition,JMJ703 itself associates with PRC2 proteins.We found that loss of PLT3,PLT4,and PLT5 function results in decreased PRC2 association H3K27me3,increased H3K4me3,and upregulated expression of genes decorated with the two marks in the root meristem.Further analyses revealed that PLT interactions with PRC2 and JMJ703 enhance the H3K27me3/H3K4me3 ratio at a set of bivalent genes,thereby maintaining their silent state.Taken together,these results uncover a chromatin mechanism by which PLTs control the stem cell fate in the rice root meristem.
基金funded by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek(GSGT.2019.019 to M.K.)supported by the Office of Science of the US Department of Energy(Contract No.DE-AC02-05CH11231).
文摘Conserved non-coding sequences(CNSs)are integral elements of transcriptional regulation.Transcriptional tuning of PLETHORA(PLT)genes that encode master regulators of plant development is vital for embryogenesis and meristematic function.However,how the expression of PLT genes is modulated through CNSs remains unclear.Through motif-based mining of upstream sequences in 120 angiosperm ge-nomes,we identified 21 conserved and lineage-specific CNSs,two of which are unusually long,similar,and colinear within eudicots.Using Arabidopsis thaliana,we demonstrate that these two deeply conserved elements,which we named BOX1 and BOX2,control PLT1 and PLT2 expression.CRISPR mutants within these elements specifically reduced PLT expression levels,and reporter lines revealed that deletion of either or both BOXes altered and/or abrogated the PLT2 expression pattern in the root tip,affecting the abil-ity to rescue the plt1 plt2 double mutant.We further show that the influence of these elements on expres-sion patterns is already exerted during embryogenesis and functional in the context of the early embryo.Finally,we reveal the existence of a BOX-mediated autoregulatory feedback loop that,in large part,explains CNS influence on expression patterns.Wethus uncover a transcriptional mechanism by which genes encoding master regulators of embryo and root meristem development are regulated.
文摘L-Cysteine plays a prominent role in sulfur metabo- lism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PiNs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and 5CR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth.
基金supported by the Eshkol fellowship issued by the Israeli Ministry of Science,Technology and Space.Research in the laboratory of Varda Rotter is supported by a Center of Excellence Grant from the Israel Science Foundation (ISF) and a Center of Excellence Grant from the Flight Attendant Medical Research Institute (FAMRI).
文摘A plethora of studies suggest that the non-transformed cellularand non-ceHular comp on ents of the tumor,collectively known as the tumor microenvironment,have a significa nt impact on the tumorigenic process.It was suggested that the microenvironment,which initially restricts tumor development,is recruited by the tumor and main tains a crosstalk that further promotes cancer progression.
基金supported by grants from the Ministry of Science and Technology of China(2015CB942901 to ZD)the National Natural Science Foundation of China(Projects 31470371 and 31222005 to ZD)+1 种基金Project funded by China Postdoctoral Science Foundation(2018T110683 to BL)the Special Support for Post-doc Creative Funding in Shandong(201701007 to BL)。
文摘Pre-mRNA(messenger RNA)splicing participates in the regulation of numerous biological processes in plants.For example,alternative splicing shapes transcriptomic responses to abiotic and biotic stress,and controls developmental programs.However,no study has revealed a role for splicing in maintaining the root stem cell niche.Here,a screen for defects in root growth in Arabidopsis thaliana identified an ethyl methane sulfonate mutant defective in pre-m RNA splicing(rdm16-4).The rdm16-4 mutant displays a short-root phenotype resulting from fewer cells in the root apical meristem.The PLETHORA1(PLT1)and PLT2 transcription factor genes are important for root development and were alternatively spliced in rdm16-4 mutants,resulting in a disordered root stem cell niche and retarded root growth.The root cap of rdm16-4 contained reduced levels of cytokinins,which promote differentiation in the developing root.This reduction was associated with the alternative splicing of genes encoding cytokinin signaling factors,such as ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN5 and ARABIDOPSIS RESPONSE REGULATORS(ARR1,ARR2,and ARR11).Furthermore,expression of the full-length coding sequence of ARR1 or exogenous cytokinin application partially rescued the short-root phenotype of rdm16-4.This reveals that the RDM16-mediated alternative splicing of cytokinin signaling components contributes to root growth.
