In the past decade, significant knowledge has accumulated regarding gibberellin (GA) signal transductlon In rice as a result of studies using multiple approaches, particularly molecular genetics. The present review ...In the past decade, significant knowledge has accumulated regarding gibberellin (GA) signal transductlon In rice as a result of studies using multiple approaches, particularly molecular genetics. The present review highlights the recent developments In the identification of GA signaling pathway components, the discovery of GA-Induced destructlon of GA signaling repressor (DELLA protein), and the possible mechanism underlying the regulation of GA- responsive gene expression in rice.展开更多
Arabidopsis De-etiolated 1 (DET1) is one of the key repressors that maintain the etiolated state of seedlings in darkness. The plant hormone gibberellic acid (GA) also participates in this process, and plants defi...Arabidopsis De-etiolated 1 (DET1) is one of the key repressors that maintain the etiolated state of seedlings in darkness. The plant hormone gibberellic acid (GA) also participates in this process, and plants deficient in GA synthesis or signaling show a partially de.etiolated phenotype in darkness. However, how DET1 and the GA pathway work in concert in repressing photomorphogenesis remains largely unknown. In this study, we found that the abundance of DELLA proteins in detl-1 was increased in comparison with that in the wildtype plants. Mutation in DET1 changed the sensitivity of hypocotyl elongation of mutant seedlings to GA and paclobutrazol (PAC), an inhibitor of GA synthesis. However, we did not find obvious differences between detl-1 and wild-type plants with regard to the bioactive GA content or the GA signaling upstream of DELLAs. Genetic data showed that removal of several DELLA proteins suppressed the detl-1 mutant phenotype more obviously than GA treatment, indicating that DET1 can regulate DELLA proteins via some other mechanisms. In addition, a large-scale transcriptomic analysis revealed that DET1 and DELLAs play antagonistic roles in regulating expression of photosynthetic and cell elongation-related genes in etiolated seedlings. Taken together, our results show that DET1 represses photomorphogenesis in darkness in part by reducing the abundance of DELLA proteins.展开更多
PICKLE(PKL), a putative CHD3 chromatin remodeling factor, has been suggested to be involved in multiple processes in Arabidopsis. Here, we confirmed the late-flowering phenotype caused by pkl mutation with pkl mutants...PICKLE(PKL), a putative CHD3 chromatin remodeling factor, has been suggested to be involved in multiple processes in Arabidopsis. Here, we confirmed the late-flowering phenotype caused by pkl mutation with pkl mutants in two different ecotypes, and investigated the possible mechanisms that account for PKL regulation of flowering time. Quantitative RT-PCR and RNA-seq assays showed that expression of the LEAFY gene(LFY) and a number of LFY-regulated floral homeotic genes were down-regulated in seedlings of the pkl mutants. As predicted, overexpression of LFY restored normal flowering time of pkl mutants. Our results suggest that PKL may be involved in regulating flowering time via LFY expression. To uncover the underlying mechanism, Ch IP-PCR using anti-PKL was performed on materials from three developmental stages of seedlings. Our results showed that PKL associated with the genomic sequences of LFY, particularly at 10-day and 25-day after germination. We also showed that loss of PKL affected H3K27me3 level at the promoter of LFY. Taken together, our data suggest that transcriptional regulation of LFY at the chromatin level by PKL may at least partially account for the late-flowering phenotype of pkl mutants.展开更多
Free cytosolic Ca^2+ ([Ca^2+]cyt) is an ubiquitous second messenger in plant cell signaling, and [Ca^2+]cyt elevation is associated with Ca^2+-permeable channels in the plasma membrane and endomembranes regulate...Free cytosolic Ca^2+ ([Ca^2+]cyt) is an ubiquitous second messenger in plant cell signaling, and [Ca^2+]cyt elevation is associated with Ca^2+-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca^2+ channels and their regulation remains limited in planta. A type of voltage- dependent Ca^2+-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba^2+ and Ca^2+, and their activities can be inhibited by micromolar Gd^3+. The unitary conductance and the reversal potential of the channels depend on the Ca^2+ or Ba^2+ gradients across the plasma membrane. The inward whole-cell Ca^2+ (Ba^2+) current, as well as the unitary current amplitude and NPo of the single Ca^2+ channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NPo of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.展开更多
Nitrogen(N)availability is a major limiting factor for plant growth and agricultural productivity.Although the gene regulation network in response to N starvation has been extensively studied,it remains unknown whethe...Nitrogen(N)availability is a major limiting factor for plant growth and agricultural productivity.Although the gene regulation network in response to N starvation has been extensively studied,it remains unknown whether N starvation has an impact on the activity of transposable elements(TEs).Here,we report that TEs can be transcriptionally activated in Arabidopsis under N starvation conditions.Through genetic screening of idm1-14 suppressors,we cloned GLU1,which encodes a glutamate synthase that catalyzes the synthesis of glutamate in the primary N assimilation pathway.We found that glutamate synthase 1(GLU1)and its functional homologs GLU2 and glutamate transport 1(GLT1)are redundantly required for TE silencing,suggesting that N metabolism can regulate TE activity.Transcriptome and methylome analyses revealed that N starvation results in genome-wide TE activation without inducing obvious alteration of DNA methylation.Genetic analysis indicated that N starvationinduced TE activation is also independent of other well-established epigenetic mechanisms,including histone methylation and heterochromatin decondensation.Our results provide new insights into the regulation of TE activity under stressful environments in planta.展开更多
基金Publication of this paper is supported by the National Natural Science Foundation of China (30624808).
文摘In the past decade, significant knowledge has accumulated regarding gibberellin (GA) signal transductlon In rice as a result of studies using multiple approaches, particularly molecular genetics. The present review highlights the recent developments In the identification of GA signaling pathway components, the discovery of GA-Induced destructlon of GA signaling repressor (DELLA protein), and the possible mechanism underlying the regulation of GA- responsive gene expression in rice.
基金This work was supported by grants to H.C. from the National Natural Science Foundation of China (31271294), the National Program on Key Basic Research Project of China (973 Program: 2011CB100101), the National High Technology Research and Development Program of China (863 Pro- gram: 2012AA10A304), the Ministry of Agriculture of China (948 Program: 2011-G2B), and State Key Laboratory of Protein and Plant Gene Research and grants to X.W.D. from the National Natural Science Foundation of China (31330048, U1031001), the National Program on Key Basic Research Project of China (973 Program: 2012CB910900), Peking-Tsinghua Center for Life Sciences, and State Key Laboratory of Protein and Plant Gene Research.ACKNOWLEDGMENTS We thank Renbo Yu, Jie Dong, and other laboratory members for their constructive discussion and help. No conflict of interest declared.
文摘Arabidopsis De-etiolated 1 (DET1) is one of the key repressors that maintain the etiolated state of seedlings in darkness. The plant hormone gibberellic acid (GA) also participates in this process, and plants deficient in GA synthesis or signaling show a partially de.etiolated phenotype in darkness. However, how DET1 and the GA pathway work in concert in repressing photomorphogenesis remains largely unknown. In this study, we found that the abundance of DELLA proteins in detl-1 was increased in comparison with that in the wildtype plants. Mutation in DET1 changed the sensitivity of hypocotyl elongation of mutant seedlings to GA and paclobutrazol (PAC), an inhibitor of GA synthesis. However, we did not find obvious differences between detl-1 and wild-type plants with regard to the bioactive GA content or the GA signaling upstream of DELLAs. Genetic data showed that removal of several DELLA proteins suppressed the detl-1 mutant phenotype more obviously than GA treatment, indicating that DET1 can regulate DELLA proteins via some other mechanisms. In addition, a large-scale transcriptomic analysis revealed that DET1 and DELLAs play antagonistic roles in regulating expression of photosynthetic and cell elongation-related genes in etiolated seedlings. Taken together, our results show that DET1 represses photomorphogenesis in darkness in part by reducing the abundance of DELLA proteins.
文摘PICKLE(PKL), a putative CHD3 chromatin remodeling factor, has been suggested to be involved in multiple processes in Arabidopsis. Here, we confirmed the late-flowering phenotype caused by pkl mutation with pkl mutants in two different ecotypes, and investigated the possible mechanisms that account for PKL regulation of flowering time. Quantitative RT-PCR and RNA-seq assays showed that expression of the LEAFY gene(LFY) and a number of LFY-regulated floral homeotic genes were down-regulated in seedlings of the pkl mutants. As predicted, overexpression of LFY restored normal flowering time of pkl mutants. Our results suggest that PKL may be involved in regulating flowering time via LFY expression. To uncover the underlying mechanism, Ch IP-PCR using anti-PKL was performed on materials from three developmental stages of seedlings. Our results showed that PKL associated with the genomic sequences of LFY, particularly at 10-day and 25-day after germination. We also showed that loss of PKL affected H3K27me3 level at the promoter of LFY. Taken together, our data suggest that transcriptional regulation of LFY at the chromatin level by PKL may at least partially account for the late-flowering phenotype of pkl mutants.
基金Supported by the National Natural Science Foundation of China (30671029)the State Key Basic Research and Development Plan of China(2006CB100100)
文摘Free cytosolic Ca^2+ ([Ca^2+]cyt) is an ubiquitous second messenger in plant cell signaling, and [Ca^2+]cyt elevation is associated with Ca^2+-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca^2+ channels and their regulation remains limited in planta. A type of voltage- dependent Ca^2+-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba^2+ and Ca^2+, and their activities can be inhibited by micromolar Gd^3+. The unitary conductance and the reversal potential of the channels depend on the Ca^2+ or Ba^2+ gradients across the plasma membrane. The inward whole-cell Ca^2+ (Ba^2+) current, as well as the unitary current amplitude and NPo of the single Ca^2+ channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NPo of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.
基金the National Natural Science Foundation of China(31970614)the National Key R&D Program of China(2018YFE0204700)。
文摘Nitrogen(N)availability is a major limiting factor for plant growth and agricultural productivity.Although the gene regulation network in response to N starvation has been extensively studied,it remains unknown whether N starvation has an impact on the activity of transposable elements(TEs).Here,we report that TEs can be transcriptionally activated in Arabidopsis under N starvation conditions.Through genetic screening of idm1-14 suppressors,we cloned GLU1,which encodes a glutamate synthase that catalyzes the synthesis of glutamate in the primary N assimilation pathway.We found that glutamate synthase 1(GLU1)and its functional homologs GLU2 and glutamate transport 1(GLT1)are redundantly required for TE silencing,suggesting that N metabolism can regulate TE activity.Transcriptome and methylome analyses revealed that N starvation results in genome-wide TE activation without inducing obvious alteration of DNA methylation.Genetic analysis indicated that N starvationinduced TE activation is also independent of other well-established epigenetic mechanisms,including histone methylation and heterochromatin decondensation.Our results provide new insights into the regulation of TE activity under stressful environments in planta.