China is one of the most important centers of origin for Citrus genetic resources. Due to the high content of secondary metabolites, mining wild Chinese Citrus for novel medical applications is promising. In this stud...China is one of the most important centers of origin for Citrus genetic resources. Due to the high content of secondary metabolites, mining wild Chinese Citrus for novel medical applications is promising. In this study, extracts of Chinese wild species from different taxonomical groups were screened for potential effects on microtubules （MTs） in vitro. MT density as a readout for nucleation, and frequency distribution over MT lengths as a readout for elongation and decay were determined by quantitative image analysis via a standardized coverslJp assay using fluorescently labelled neurotubulin. Extract from peels of Citrus ichangensis Swing. strongly increased the density of MTs; whereas, extract from peels of Cfurs limon （L.） Burm.f. exerted the opposite effect. Extract from pulp of Citrus limonia Osbeck promoted MT elongation, and in addition induced a small population of very long MTs. These data suggest that wild Chinese Citrus harbour compounds that act specifically on different aspects of MT nucleation, elongation, and decay.展开更多
Specific populations of plant microtubules cooperate with the plasma membrane to sense and process abiotic stress signals,such as cold stress.The current study derived from the question,to what extent this perception ...Specific populations of plant microtubules cooperate with the plasma membrane to sense and process abiotic stress signals,such as cold stress.The current study derived from the question,to what extent this perception system is active in biotic stress signalling.The experimental system consisted of grapevine cell lines,where microtubules or actin filaments are visualised by GFP,such that their response became visible in vivo.We used the bacterial elicitors harpin(inducing cell-death related defence),or flg22(inducing basal immunity)in combination with modulators of membrane fluidity,or microtubules.We show that DMSO,a membrane rigidifier,can cause microtubule bundling and trigger defence responses,including activation of phytoalexin transcripts.However,DMSO inhibited the gene expression in response to harpin,while promoting the gene expression in response to flg22.Treatment with DMSO also rendered microtubules more persistent to harpin.Paradoxically,Benzylalcohol(BA),a membrane fluidiser,acted in the same way as DMSO.Neither GdCl_(3),nor diphenylene iodonium were able to block the inhibitory effect of membrane rigidification on harpin-induced gene expression.Treatment with taxol stabilised microtubule against harpin but amplified the response of PAL transcripts.Therefore,the data support implications of a model that deploys specific responses to pathogen-derived signals.展开更多
Cell polarity and axes are central for plant morphogenesis. To study how polarity and axes are induced de novo, we investigated protoplasts of tobacco Nicotiana tabacum cv. BY-2 expressing fluorescently- tagged cytosk...Cell polarity and axes are central for plant morphogenesis. To study how polarity and axes are induced de novo, we investigated protoplasts of tobacco Nicotiana tabacum cv. BY-2 expressing fluorescently- tagged cytoskeletal markers. We standardized the system to such a degree that we were able to generate quantitative data on the temporal patterns of regeneration stages. The synthesis of a new cell wall marks the transition to the first stage of regeneration, and proceeds after a long preparatory phase within a few minutes. During this preparatory phase, the nucleus migrates actively, and cytoplasmic strands remodel vigorously. We probed this system for the effect of anti-cytoskeletal compounds, inducible bundling of actin, RGD-peptides, and temperature. Suppression of actin dynamics at an early stage leads to aberrant tripolar cells, whereas suppression of microtubule dynamics produces aberrant sausage- like cells with asymmetric cell walls. We integrated these data into a model, where the microtubular cytoskeleton conveys positional information between the nucleus and the membrane controlling the release or activation of components required for cell wall synthesis. Cell wall formation is followed by the induction of a new cell pole requiring dynamic actin filaments, and the new cell axis is manifested as elongation growth perpendicular to the orientation of the aligned cortical microtubules.展开更多
Traditional Chinese medicine(TCM)belongs to the most elaborate and extensive systems of plant-based healing.The herb Northern Ban Lan(Isatis tinctoria)is famous for its antiviral and anti-inflammatory activity.Althoug...Traditional Chinese medicine(TCM)belongs to the most elaborate and extensive systems of plant-based healing.The herb Northern Ban Lan(Isatis tinctoria)is famous for its antiviral and anti-inflammatory activity.Although numerous components isolated from I.tinctoria have been characterized so far,their modes of action have remained unclear.Here,we show that extracts from I.tinctoria exert antimicrotubular activity.Using time-lapse microscopy in living tobacco BY-2(Nicotiana tabacum L.cvBrightYellow2)cellsexpressing greenfluorescentprotein-tubulin,weuse activity-guided fractionation to screen out the biologically active compounds of I.tinctoria.Among 54 fractions obtained from either leaves or roots of I.tinctoria by methanol(MeOH/H_(2)O 8:2),or ethyl acetate extraction,one specific methanolic root fraction was selected,because it efficiently and rapidly eliminated microtubules.By combination of further purification with ultrahigh-performance liquid chromatography and high-resolution tandem mass spectrometry most of the bioactivity could be assigned to the glucosinolate compound glucobrassicin.Glucobrassicin can also affect microtubules and induce apoptosis in HeLa cells.In the light of these findings,the antiviral activity of Northern Ban Lan is discussed in the context of microtubules being hijacked by many viral pathogens for cell-to-cell spread.展开更多
The detyrosination/retyrosination cycle is the most common post-translational modification of α-tubulin.Removal of the conserved C-terminal tyrosine of α-tubulin by a still elusive tubulin tyrosine carboxypeptidase,...The detyrosination/retyrosination cycle is the most common post-translational modification of α-tubulin.Removal of the conserved C-terminal tyrosine of α-tubulin by a still elusive tubulin tyrosine carboxypeptidase, and religation of this tyrosine by a tubulin tyrosine ligase(TTL), are probably common to all eukaryotes. Interestingly, for plants, the only candidates qualifying as potential TTL homologs are the tubulin tyrosine ligase-like 12 proteins. To get insight into the biological functions of these potential TTL homologs, we cloned the rice TTL-like 12 protein(Os TTLL12)andgeneratedoverexpression Os TTLL12-RFP lines in both rice and tobacco BY-2 cells. We found, unexpectedly, that overexpression of this Os TTLL12-RFP increased the relative abundance of detyrosinated α-tubulin in both coleoptile and seminal root, correlated with more stable microtubules. This was independent of the respective orientation of cortical microtubule, and followed by correspondingly changing growth of coleoptiles and seminal roots. A perturbed organization of phragmoplast microtubules and disoriented cell walls were further characteristics of this phenotype. Thus, the elevated tubulin detyrosination in consequence of Os TTLL12 overexpression affects structural and dynamic features of microtubules, followed by changes in the axiality of cell plate deposition and, consequently, plant growth.展开更多
Nuclear migration and positioning are crucial for the morphogenesis of plant cells. We addressed the potential role of nuclear positioning for polarity induction using an experimental system based on regenerating prot...Nuclear migration and positioning are crucial for the morphogenesis of plant cells. We addressed the potential role of nuclear positioning for polarity induction using an experimental system based on regenerating protoplasts, where the induction of a cell axis de novo can be followed by quantification of specific regeneration stages. Using overexpression of fluorescently tagged extranuclear （perinu- clear actin basket, kinesins with a calponin homology domain （KCH）） as well as intranuclear （histone H2B） factors of nuclear positioning and time-lapse series of the early stages of regeneration, we found that nuclear position is no prerequi- site for polarity formation. However, polarity formation and nuclear migration were both modulated in the transgenic lines, indicating that both phenomena depend on factors affecting cytoskeletal tensegrity and chromatin structure. We integrated these findings into a model where retrograde signals are required for polarity induction. These signals travel via the cytoskeleton from the nucleus toward targets at the plasma membrane.展开更多
Grapevine cultivation has been gaining commercial popularity in many parts of the world due to the high yield and versatility of this horticultural crop.A recent survey from the International Organization of Vine and ...Grapevine cultivation has been gaining commercial popularity in many parts of the world due to the high yield and versatility of this horticultural crop.A recent survey from the International Organization of Vine and Wine(OIV)estimated that the global area under vine cultivation in 2018 was about 7.4 million hectares and that the world production of grapes was about 77.8 million tons in total(OIV,2019).The majority of the global grape yield is used for producing wines,fresh fruit,and raisins,bringing in annual revenue of billions of US dollars(Alston and Sambucci,2019).In addition to its economic value,the grapevine is also a useful model for the study of the genetic basis of clonality,fruit development,sex determination,grafting,evolution,and domestication(This et al.,2006).Furthermore,for many countries in the world traditional viniculture and viticulture are important emblems of cultural identity.All these factors have made grapevine one of the most heavily invested plants in horticultural research.展开更多
基金supported by the Fundamental Research Funds for the Central Universities,China(SWU113107 and XDJK2014A014)the Programs for Research on the Teaching Reform of Graduate Education and Basic Science and Cutting-edge Technology Research(yjg153078 and cstc2016jcyj A0489) in Chongqing,ChinaA fellowship of Chinese “111” project(B12006) to Mr. Tan Si in lab of Prof. Peter Nick,Molecular Cell Biology,Botanical Institute,Karlsruhe Institute of Technology,Germany
文摘China is one of the most important centers of origin for Citrus genetic resources. Due to the high content of secondary metabolites, mining wild Chinese Citrus for novel medical applications is promising. In this study, extracts of Chinese wild species from different taxonomical groups were screened for potential effects on microtubules （MTs） in vitro. MT density as a readout for nucleation, and frequency distribution over MT lengths as a readout for elongation and decay were determined by quantitative image analysis via a standardized coverslJp assay using fluorescently labelled neurotubulin. Extract from peels of Citrus ichangensis Swing. strongly increased the density of MTs; whereas, extract from peels of Cfurs limon （L.） Burm.f. exerted the opposite effect. Extract from pulp of Citrus limonia Osbeck promoted MT elongation, and in addition induced a small population of very long MTs. These data suggest that wild Chinese Citrus harbour compounds that act specifically on different aspects of MT nucleation, elongation, and decay.
基金This work was supported by project of the National Natural Science Foundation of China 32102308fellowships from the China Scholarship Council to Pingyin Guan and Wenjing Shi.
文摘Specific populations of plant microtubules cooperate with the plasma membrane to sense and process abiotic stress signals,such as cold stress.The current study derived from the question,to what extent this perception system is active in biotic stress signalling.The experimental system consisted of grapevine cell lines,where microtubules or actin filaments are visualised by GFP,such that their response became visible in vivo.We used the bacterial elicitors harpin(inducing cell-death related defence),or flg22(inducing basal immunity)in combination with modulators of membrane fluidity,or microtubules.We show that DMSO,a membrane rigidifier,can cause microtubule bundling and trigger defence responses,including activation of phytoalexin transcripts.However,DMSO inhibited the gene expression in response to harpin,while promoting the gene expression in response to flg22.Treatment with DMSO also rendered microtubules more persistent to harpin.Paradoxically,Benzylalcohol(BA),a membrane fluidiser,acted in the same way as DMSO.Neither GdCl_(3),nor diphenylene iodonium were able to block the inhibitory effect of membrane rigidification on harpin-induced gene expression.Treatment with taxol stabilised microtubule against harpin but amplified the response of PAL transcripts.Therefore,the data support implications of a model that deploys specific responses to pathogen-derived signals.
基金supported by funds from the Sino-German Center for Research Promotion, GZ 614 "Probing the Self-Organization of Plant Cells by Micropattern and Microfluidics"
文摘Cell polarity and axes are central for plant morphogenesis. To study how polarity and axes are induced de novo, we investigated protoplasts of tobacco Nicotiana tabacum cv. BY-2 expressing fluorescently- tagged cytoskeletal markers. We standardized the system to such a degree that we were able to generate quantitative data on the temporal patterns of regeneration stages. The synthesis of a new cell wall marks the transition to the first stage of regeneration, and proceeds after a long preparatory phase within a few minutes. During this preparatory phase, the nucleus migrates actively, and cytoplasmic strands remodel vigorously. We probed this system for the effect of anti-cytoskeletal compounds, inducible bundling of actin, RGD-peptides, and temperature. Suppression of actin dynamics at an early stage leads to aberrant tripolar cells, whereas suppression of microtubule dynamics produces aberrant sausage- like cells with asymmetric cell walls. We integrated these data into a model, where the microtubular cytoskeleton conveys positional information between the nucleus and the membrane controlling the release or activation of components required for cell wall synthesis. Cell wall formation is followed by the induction of a new cell pole requiring dynamic actin filaments, and the new cell axis is manifested as elongation growth perpendicular to the orientation of the aligned cortical microtubules.
基金supported by fellowships from the China Scholarship Council。
文摘Traditional Chinese medicine(TCM)belongs to the most elaborate and extensive systems of plant-based healing.The herb Northern Ban Lan(Isatis tinctoria)is famous for its antiviral and anti-inflammatory activity.Although numerous components isolated from I.tinctoria have been characterized so far,their modes of action have remained unclear.Here,we show that extracts from I.tinctoria exert antimicrotubular activity.Using time-lapse microscopy in living tobacco BY-2(Nicotiana tabacum L.cvBrightYellow2)cellsexpressing greenfluorescentprotein-tubulin,weuse activity-guided fractionation to screen out the biologically active compounds of I.tinctoria.Among 54 fractions obtained from either leaves or roots of I.tinctoria by methanol(MeOH/H_(2)O 8:2),or ethyl acetate extraction,one specific methanolic root fraction was selected,because it efficiently and rapidly eliminated microtubules.By combination of further purification with ultrahigh-performance liquid chromatography and high-resolution tandem mass spectrometry most of the bioactivity could be assigned to the glucosinolate compound glucobrassicin.Glucobrassicin can also affect microtubules and induce apoptosis in HeLa cells.In the light of these findings,the antiviral activity of Northern Ban Lan is discussed in the context of microtubules being hijacked by many viral pathogens for cell-to-cell spread.
基金This work was supported by a fellowship from the the Chinese Scholarship Council to Kunxi ZhangOpen access funding enabled and organized by Projekt DEAL。
文摘The detyrosination/retyrosination cycle is the most common post-translational modification of α-tubulin.Removal of the conserved C-terminal tyrosine of α-tubulin by a still elusive tubulin tyrosine carboxypeptidase, and religation of this tyrosine by a tubulin tyrosine ligase(TTL), are probably common to all eukaryotes. Interestingly, for plants, the only candidates qualifying as potential TTL homologs are the tubulin tyrosine ligase-like 12 proteins. To get insight into the biological functions of these potential TTL homologs, we cloned the rice TTL-like 12 protein(Os TTLL12)andgeneratedoverexpression Os TTLL12-RFP lines in both rice and tobacco BY-2 cells. We found, unexpectedly, that overexpression of this Os TTLL12-RFP increased the relative abundance of detyrosinated α-tubulin in both coleoptile and seminal root, correlated with more stable microtubules. This was independent of the respective orientation of cortical microtubule, and followed by correspondingly changing growth of coleoptiles and seminal roots. A perturbed organization of phragmoplast microtubules and disoriented cell walls were further characteristics of this phenotype. Thus, the elevated tubulin detyrosination in consequence of Os TTLL12 overexpression affects structural and dynamic features of microtubules, followed by changes in the axiality of cell plate deposition and, consequently, plant growth.
基金supported by a Ph.D. fellowship of State of BadenWürttemberg (Landesgraduiertenfrderung) to L. Brochhausenfunds from the Deutsche Forschungsgemeinschaft (NI 324/19-1)
文摘Nuclear migration and positioning are crucial for the morphogenesis of plant cells. We addressed the potential role of nuclear positioning for polarity induction using an experimental system based on regenerating protoplasts, where the induction of a cell axis de novo can be followed by quantification of specific regeneration stages. Using overexpression of fluorescently tagged extranuclear （perinu- clear actin basket, kinesins with a calponin homology domain （KCH）） as well as intranuclear （histone H2B） factors of nuclear positioning and time-lapse series of the early stages of regeneration, we found that nuclear position is no prerequi- site for polarity formation. However, polarity formation and nuclear migration were both modulated in the transgenic lines, indicating that both phenomena depend on factors affecting cytoskeletal tensegrity and chromatin structure. We integrated these findings into a model where retrograde signals are required for polarity induction. These signals travel via the cytoskeleton from the nucleus toward targets at the plasma membrane.
基金Yunnan Provincial Key Programs of Yunnan Eco-friendly Food International Cooperation Research Center Project(2019ZG00908).
文摘Grapevine cultivation has been gaining commercial popularity in many parts of the world due to the high yield and versatility of this horticultural crop.A recent survey from the International Organization of Vine and Wine(OIV)estimated that the global area under vine cultivation in 2018 was about 7.4 million hectares and that the world production of grapes was about 77.8 million tons in total(OIV,2019).The majority of the global grape yield is used for producing wines,fresh fruit,and raisins,bringing in annual revenue of billions of US dollars(Alston and Sambucci,2019).In addition to its economic value,the grapevine is also a useful model for the study of the genetic basis of clonality,fruit development,sex determination,grafting,evolution,and domestication(This et al.,2006).Furthermore,for many countries in the world traditional viniculture and viticulture are important emblems of cultural identity.All these factors have made grapevine one of the most heavily invested plants in horticultural research.
