Seed germination is a critical developmental switch from a quiescent state to active growth,which involves extensive changes in metabolism,gene expression,and cellular identity.However,our understanding of epigenetic ...Seed germination is a critical developmental switch from a quiescent state to active growth,which involves extensive changes in metabolism,gene expression,and cellular identity.However,our understanding of epigenetic and transcriptional reprogramming during this process is limited.The histone H3 lysine 27 trimethylation(H3K27me3)plays a key role in regulating gene repression and cell fate specification.Here,we profile H3K27me3 dynamics and dissect the function of H3K27 demethylation during germination in Arabidopsis.Our temporal genome-wide profiling of H3K27me3 and transcription reveals delayed H3K27me3reprogramming compared with transcriptomic changes during germination,with H3K27me3 changes mainly occurring when the embryo is entering into vegetative development.RELATIVE OF EARLY FLOWERING 6(REF6)-mediated H3K27 demethylation is necessary for robust germination but does not significantly contribute to H3K27me3 dynamics during germination,but rather stably establishes an H3K27me3-depleted state that facilitates the activation of hormone-related and expansin-coding genes important for germination.We also show that the REF6 chromatin occupancy is gradually established during germination to counteract increased Polycomb repressive complex 2(PRC2).Our study provides key insights into the H3K27me3 dynamics during germination and suggests the function of H3K27me3 in facilitating cell fate switch.Furthermore,we reveal the importance of H3K27 demethylation-established transcriptional competence in gene activation during germination and likely other developmental processes.展开更多
The H3K27 methyltransferase CLF inhibits lateral root(LR) formation through depositing the repressive H3K27me3 mark to the chromatin of PIN1, a key polar auxin transporter gene. Here, we show that the H3K27me3 demethy...The H3K27 methyltransferase CLF inhibits lateral root(LR) formation through depositing the repressive H3K27me3 mark to the chromatin of PIN1, a key polar auxin transporter gene. Here, we show that the H3K27me3 demethylase REF6 promotes lateral root primordium initiation and LR emergence. REF6 directly binds to the chromatin of PIN1/3/7. Dysfunction in REF6 results in increased levels of H3K27me3 on PIN1/3/7 and suppressed expression of PIN genes. Genetic analysis of the clf ref6 double mutant revealed an antagonistic action between CLF and REF6, in terms of LR formation.Our findings indicate that H3K27 methylation and demethylation activities are likely coordinated to ensure proper LR organogenesis.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Precision Seed Design and Breeding,XDA24020303)the National Key R&D Program of China(2019YFA0903903)the National Natural Science Foundation of China(31970527,32170545,and 32150610472)。
文摘Seed germination is a critical developmental switch from a quiescent state to active growth,which involves extensive changes in metabolism,gene expression,and cellular identity.However,our understanding of epigenetic and transcriptional reprogramming during this process is limited.The histone H3 lysine 27 trimethylation(H3K27me3)plays a key role in regulating gene repression and cell fate specification.Here,we profile H3K27me3 dynamics and dissect the function of H3K27 demethylation during germination in Arabidopsis.Our temporal genome-wide profiling of H3K27me3 and transcription reveals delayed H3K27me3reprogramming compared with transcriptomic changes during germination,with H3K27me3 changes mainly occurring when the embryo is entering into vegetative development.RELATIVE OF EARLY FLOWERING 6(REF6)-mediated H3K27 demethylation is necessary for robust germination but does not significantly contribute to H3K27me3 dynamics during germination,but rather stably establishes an H3K27me3-depleted state that facilitates the activation of hormone-related and expansin-coding genes important for germination.We also show that the REF6 chromatin occupancy is gradually established during germination to counteract increased Polycomb repressive complex 2(PRC2).Our study provides key insights into the H3K27me3 dynamics during germination and suggests the function of H3K27me3 in facilitating cell fate switch.Furthermore,we reveal the importance of H3K27 demethylation-established transcriptional competence in gene activation during germination and likely other developmental processes.
基金supported by the Science and Technology Commission of Shanghai Municipality(15JC1400800 to G.R.)the National Natural Science Foundation of China(31622009 to G.R.,31700246 to J.G.)
文摘The H3K27 methyltransferase CLF inhibits lateral root(LR) formation through depositing the repressive H3K27me3 mark to the chromatin of PIN1, a key polar auxin transporter gene. Here, we show that the H3K27me3 demethylase REF6 promotes lateral root primordium initiation and LR emergence. REF6 directly binds to the chromatin of PIN1/3/7. Dysfunction in REF6 results in increased levels of H3K27me3 on PIN1/3/7 and suppressed expression of PIN genes. Genetic analysis of the clf ref6 double mutant revealed an antagonistic action between CLF and REF6, in terms of LR formation.Our findings indicate that H3K27 methylation and demethylation activities are likely coordinated to ensure proper LR organogenesis.
