Morphological variations of the nucleus in starchy endosperm cell were observed by theelectron-transmisson microscope during endosperm development in rice. Along with thedevelopment of the starchy endosperm, the nucle...Morphological variations of the nucleus in starchy endosperm cell were observed by theelectron-transmisson microscope during endosperm development in rice. Along with thedevelopment of the starchy endosperm, the nuclei of the cells showed chromatin condensation,the typical feature of programmed cell death (PCD). The nuclei also showed nucleusdeformation, disruption of nuclear envelope, nucleoplasm leaking into the cytoplasm andnucleus disintegration resulting in nuclear residue formation. From the nucleus deformationto the nucleus disintegration, the morphological changes of the nucleus were orderlyprogressive. This indicated that the cell death of starchy endosperm in rice wasprogrammed cell death. Evans Blue staining observation showed that the cell death wasinitially detected in the central part of starchy endosperm in rice, then expandedoutward. The activities of superoxide dismutase (SOD) and catalase (CAT) in rice starchyendosperm both descended continuously as development progressed. The analysis of DNA ofrice starchy endosperm did not show the presence of DNA laddering. The above resultsshowed that the cell death of starchy endosperm in rice was a special form of PCD.展开更多
There is increasing evidence shows that programmed cell death (PCD) can occur underphysiological, pathological or stress conditions in plants. The present review describes themorphological and biochemical characterist...There is increasing evidence shows that programmed cell death (PCD) can occur underphysiological, pathological or stress conditions in plants. The present review describes themorphological and biochemical characteristics, physiological functions, and the research significance ofplant PCD in detail as well as makes comparison betWeen these aspects with those in animals. Inaddition, this paper is also making exploration of the possible pathway for signal transduction, geneticregulation of plant PCD, origin and evolution of PCD and proposes a tactic for research on plant PCDalthough it is still in a preliminary stage.Compared to PCD in animals, PCD in plants under various conditions has revealed much greaterdifference in morphological and biochemical characteristics, which presents different essence far fromthe definition of apoptosis of animals. Nevertheless, no inflammation, specific fragmentation of DNAand rise of the activities of endonuclease and protease in plant PCD are still typical hallmarks fordistinguishing PCD from necrosis. On view of molecular level, as in animals, PCD in plants is alsoregulated by specific genes and involves signal transduction pathway with the involvement of a varietyof signal molecules.The physiological functions of plant PCD are similar to those in animals too. In the importantphysiological and pathological processes in plants, i.e., during reproduction, development, growth,senescenced disease-resistance, and stress-resistance against adverse circumstance conditions, PCDtakes on functions as important as proliferation throughout the whole life cycle of living organisms.Obviously, the research on PCD in plants is of vital importance that should not be ignored either intheory or in agricultural production.At present, the research on PCD in plants is focusing on collecting morphological and biochemicalevidences. But many molecules of initiation signal participating in plant PCD have been identified andseveral genes directly related to this process were isolated, which provide useful enlightenment forillustrating signal transduction pathway of PCD. Moreover, some conserved signal molecules andregulating genes were found in plant PCD, and caspase-like proteases have been detected in HR celldeath as well as in development-associated PCD. These data provide strong evidence at molecular levelfor conservation and the origin and evolution of PCD.1 The authors want to extend the sincerely thanks to Prof. Michele C. Heath (University of Toronto, Canada),Prof. Niroo Fukuda (University of Tokyo, Japan), Prof. Duran L. Nooden (University of Michigan, USA),Prof. Chris Lamb (Salk institute, California), Prof. Sarah Hake (Agricultural Research Service, USA), Prof.David L. Vaux (The Walter and Eliza Hall insititue of Medical Research, Post Office Royal MelbourneHospital, Australia), Associate Prof. Jeffrey L. Dangl (University of North Carolina, USA), Associate Prof.Eric Lain (The State University of New Jersey, USA), Dr. Maki Katsuhara (Okayama University, Japan),Prof. Sarah Hake (AgricultUral Research Service, USA), Dr. Peter P. Repetti (University of California,USA), Da Blazena Koukalova (Academy of Sciences of the Czech Republic, CZ), Dr. Iona Weir(Horticulture and Food Research Institute of New Zealand, New Zealand), Dr. Thorsten Jabs (Institute forBiology III, Germany), Dr. Hong Wang (University of California, USA) and Dr. Patrick Gallois (Universityof Perpignan, France) for their kind providing their personal latest data of their research concerned andoffering academic exchanges with us.This project is granted by the National Natural Science Foundation of China (No. 39870423) and by StateCommission of Education, Doctorate Spot Foundation.Author for correspondence. E-mail: ycsong@whu.edu.cn.Evidences in various aspects indicate that PCD origins from prokaryote, and various forms of PCD arefound along the phylogenic tree.Conclusion: A variety of endogenous and exogenous signals can break the homeostasis within plantbody and result in differentiation, proliferation, quiescence, or death of cell at length展开更多
Cell death is an important physiological phenomenon in life.It can be programmed or unprogrammed.Unprogrammed cell death is usually induced by abiotic or biotic stress.Recent studies have shown that many proteins regu...Cell death is an important physiological phenomenon in life.It can be programmed or unprogrammed.Unprogrammed cell death is usually induced by abiotic or biotic stress.Recent studies have shown that many proteins regulate both cell death and immunity in plants.Here,we provide a review on the advances in plant immunity with cell death,especially the molecular regulation and underlying mechanisms of those proteins involved in both cell death and plant immunity.In addition,we discuss potential approaches toward improving plant immunity without compromising plant growth.展开更多
To investigate the changes of tissue transglutaminase activity, the leaves and young panicles of rice at different developmental stages were excised from the Honglian-type cytoplasmic male sterile line, Yuetai A and i...To investigate the changes of tissue transglutaminase activity, the leaves and young panicles of rice at different developmental stages were excised from the Honglian-type cytoplasmic male sterile line, Yuetai A and its maintainer line, Yuetai B, respectively. An ELISA measurement protocol for tissue transglutaminase activity detection in rice was well established. The results indicated that the tissue transglutaminase activity was regulated positively by calcium cation, and the tissue transglutaminase activity in senescent leaves was remarkably higher than that in young leaves. No distinct difference was noted between Yuetai A and Yuetai B. Moreover, from the tetrad to binucleate stages the tissue transglutaminase activity increased gradually with the progression of the young panicle development and up to maximum at binucleate stage in Yuetai A. However, no similar changes were observed in Yuetai B. This indicates that the tissue transglutaminase is involved in cell programmed death in abortive pollen.展开更多
The early stage of pollen chamber development in ovule and the cytological mechanism of nucellar cell death were studied in Ginkgo biloba L. DNA ladder appearance and TUNEL assay demonstrated that the nucellar cel...The early stage of pollen chamber development in ovule and the cytological mechanism of nucellar cell death were studied in Ginkgo biloba L. DNA ladder appearance and TUNEL assay demonstrated that the nucellar cell death, doomed to bring about pollen chamber formation, was a process of programmed cell death (PCD). A spatial distribution of PCD was visualized during the development of pollen chamber. Together with the observation under the scanning electron microscope, these results have revealed that the early developmental pattern of pollen chamber consists of four phases. Firstly, several layers of the nucellar cells at the micropylar end elongate longitudinally. Thereafter, the uppermost layer of the nucellar cells at the micropylar end initiate PCD; and the nucellar cell death extends in a basally and laterally oriented direction to form a cavity. Finally, the epidermal cells at the micropylar end detach from the other epidermis by dehiscence, bringing about the opening of the pollen chamber. The early development of pollen chamber begins sometime after the stage of megasporocyte and continues by the time of the formation of megaspore tetrad, and finally completes at the stage of development of female gametophyte. This shows a synchronous development of megaspore and pollen chamber.展开更多
Abstract: Cell death is a common event in all types of plant organisms. Understanding the phenomenon of programmed cell death (PCD) is an important area of research for plant scientists because of its role in senescen...Abstract: Cell death is a common event in all types of plant organisms. Understanding the phenomenon of programmed cell death (PCD) is an important area of research for plant scientists because of its role in senescence and the post-harvest quality of ornamentals, fruits, and vegetables. In the present paper, PCD in relation to petal senescence in ornamental plants is reviewed. Morphological, anatomical, physiological, and biochemical changes that are related to PCD in petals, such as water content, sink-source relationships, hormones, genes, and signal transduction pathways, are discussed. Several approaches to improving the quality of post-harvest ornamentals are reviewed and some prospects for future research are given.展开更多
Programmed cell death (PCD) of the nucellar cells at the micropylar end is involved in pollen chamber morphogenesis in Ginkgo biloba L. A development-course observation of the morphological changes in the nucellar cel...Programmed cell death (PCD) of the nucellar cells at the micropylar end is involved in pollen chamber morphogenesis in Ginkgo biloba L. A development-course observation of the morphological changes in the nucellar cells undergoing PCD to form pollen chamber was performed. During the PCD, the nucellar cells degraded their cellular components through an orderly progression. Through the vactiolation, the cytosol was engulfed by the enlarging vacuole, leaving out various organelles, which remained morphologically integrated. As the vacuolation continued, the vacuole collapsed with the breakage of the tonoplast and the cytosol disappeared completely. Organelles were subsequently destroyed. Ultimately, nucellar cells digested away all of their cytoplasm, leaving with cell walls. They became collapsed as the nucellus developed. Intracellular membranes were strikingly changed, playing a role in leading to cell death. Some of these noticeable changes were the appearance of multivesicular body, multicycle-like membranes, membrane-bounded bodies containing some organelles, tonoplast rupture and numerous vesicles. The dehiscence of the apical epidermis, resulting in the opening, appeared to have followed two different pathways with one involving a specific epidermal cell autolysis and the other by detachment from middle lamella of two neighboring epidermal cells without cell autolysis. The specific epidermal cells had been dead prior to the dehiscence of the apical epidermis, which marked the sites of the dehiscence followed. In view of the changes in the cellular morphology, a process of nucellar cell PCD in the course of the pollen chamber formation was demonstrated.展开更多
The maize (Zea mays) spikelet consists of two florets, each of which contains three developmentally synchronized anthers. Morphologically, the anthers in the upper and lower florets proceed through apparently simila...The maize (Zea mays) spikelet consists of two florets, each of which contains three developmentally synchronized anthers. Morphologically, the anthers in the upper and lower florets proceed through apparently similar developmental programs. To test for global differences in gene expression and to identify genes that are coordinately regulated during maize anther development, RNA samples isolated from upper and lower floret anthers at six developmental stages were hybridized to cDNA microarrays. Approximately 9% of the tested genes exhibited statistically significant differences in expression between anthers in the upper and lower florets. This finding indicates that several basic biological processes are differentially regulated between upper and lower floret anthers, including metabolism, protein synthesis and signal transduction. Genes that are coordinately regulated across anther development were identified via cluster analysis. Analysis of these results identified stage-specific, early in development, late in development and bi-phasic expression profiles. Quantitative RT-PCR analysis revealed that four genes whose homologs in other plant species are involved in programmed cell death are up-regulated just prior to the time the tapetum begins to visibly degenerate (i.e., the mid-microspore stage). This finding supports the hypothesis that developmentally normal tapetal degeneration occurs via programmed cell death.展开更多
The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection b...The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection by biotrophic pathogens, but can, in fact, enhance infection by necrotrophic pathogens like Botrytis cinerea. In addition to signaling the induction of the HR, reactive oxygen species (ROS) produced during the oxidative burst are?antimicrobial. We hypothesize that pathogens such as B. cinerea survive the antimicrobial effects of ROS, at least partially by secreting the antioxidant mannitol during infection. This is supported by the previous observation that overexpression of the catabolic enzyme mannitol dehydrogenase (MTD) can decrease a plants susceptibility to mannitol-secreting pathogens like B. cinerea. To extend the above hypothesis, and test the general utility of this approach in an important horticultural crop, we overexpressed celery MTD in tomato (Solanum lycopersicum cv. “Moneymaker”). In these studies, we observed a significant increase (up to 90%) in resistance to B. cinerea in transgenic tomatoes expressing high amounts of MTD.展开更多
Secondary xylem development has long been recognized as a typical case of programmed cell death (PCD) in plants. During PCD, the degradation of genomic DNA is catalyzed by endonucleases. However, to date, no endonuc...Secondary xylem development has long been recognized as a typical case of programmed cell death (PCD) in plants. During PCD, the degradation of genomic DNA is catalyzed by endonucleases. However, to date, no endonuclease has been shown to participate in secondary xylem development. Two novel Ca^2+-dependent DNase genes, EuCaN1 and EuCaN2, were identified from the differentiating secondary xylem of the tree Eucommia ulmoides Oliv., their functions were studied by DNase activity assay, in situ hybridization, protein immunolocalization and virus-induced gene silencing experiments. Full-length cDNAs of EuCaN1 and EuCaN2 contained an open reading frame of 987 bp, encoding two proteins of 328 amino acids with SNase-like functional domains. The genomic DNA sequence for EuCaN1 had no introns, while EuCaN2 had 8 introns. EuCaN1 and EuCaN2 digested ssDNA and dsDNA with Ca^2+-dependence at neutral pH. Their expression was confined to differentiating secondary xylem cells and the proteins were localized in the nucleus. Their activity dynamics was closely correlated with secondary xylem development. Secondary xylem cell differentiation is influenced by RNAi of endonuclease genes. The results provide evidence that the Ca^2+-dependent DNases are involved in secondary xylem development.展开更多
The spatial and temporal distributions of programmed cell death (PCD) in developing central nervous system (CNS) of human fetuses ranging from 12 to 39 weeks of gestation were investigated using techniques of flow cyt...The spatial and temporal distributions of programmed cell death (PCD) in developing central nervous system (CNS) of human fetuses ranging from 12 to 39 weeks of gestation were investigated using techniques of flow cytometry and terminal transferase-mediated nick end labeling (TUNEL). The results showed that PCD did occur in every representative brain region of all fetuses examined in different stages. It was found that there were two peaks of PCD appearing at the 12th and 39th weeks respectively, which suggested that the first peak of apoptosis may be involved in the selective elimination of neurons overproduced during the early development and the second may play an important role in establishing the correct neuronal circuitry.展开更多
Sphinganine or dihydrosphingosine (d18:0, DHS), one of the most abundant free sphingoid Long Chain Base (LCB) in plants, has been recently shown to induce both cytosolic and nuclear calcium transient increases an...Sphinganine or dihydrosphingosine (d18:0, DHS), one of the most abundant free sphingoid Long Chain Base (LCB) in plants, has been recently shown to induce both cytosolic and nuclear calcium transient increases and a correlated Programmed Cell Death (PCD) in tobacco BY-2 cells. In this study, in order to get deeper insight into the LCB signaling pathway leading to cell death, the putative role of Reactive Oxygen Species (ROS) has been investigated. We show that DHS triggers a rapid dose-dependent production of H2O2 that is blocked by diphenyleniodonium (DPI), indicating the involvement of NADPH oxidase(s) in the process. In addition, while DPI does not block DHS-induced calcium increases, the ROS production is inhibited by the broad spectrum calcium channel blocker lanthanum (La^3+). Therefore, ROS production occurs downstream of DHS-induced Ca^2+ transients. Interestingly, DHS activates expression of defense-related genes that is inhibited by both La^3+ and DPI. Since DPI does not prevent DHS-induced cell death, these results strongly indicate that DHS-induced H2O2 production is not implicated in PCD mechanisms but rather would be associated to basal cell defense mechanisms.展开更多
基金supported by the National Natural Science Foundation of China(30070363)the Foundation for Doctorate Research of Ministry of Education,China(200005041).
文摘Morphological variations of the nucleus in starchy endosperm cell were observed by theelectron-transmisson microscope during endosperm development in rice. Along with thedevelopment of the starchy endosperm, the nuclei of the cells showed chromatin condensation,the typical feature of programmed cell death (PCD). The nuclei also showed nucleusdeformation, disruption of nuclear envelope, nucleoplasm leaking into the cytoplasm andnucleus disintegration resulting in nuclear residue formation. From the nucleus deformationto the nucleus disintegration, the morphological changes of the nucleus were orderlyprogressive. This indicated that the cell death of starchy endosperm in rice wasprogrammed cell death. Evans Blue staining observation showed that the cell death wasinitially detected in the central part of starchy endosperm in rice, then expandedoutward. The activities of superoxide dismutase (SOD) and catalase (CAT) in rice starchyendosperm both descended continuously as development progressed. The analysis of DNA ofrice starchy endosperm did not show the presence of DNA laddering. The above resultsshowed that the cell death of starchy endosperm in rice was a special form of PCD.
文摘There is increasing evidence shows that programmed cell death (PCD) can occur underphysiological, pathological or stress conditions in plants. The present review describes themorphological and biochemical characteristics, physiological functions, and the research significance ofplant PCD in detail as well as makes comparison betWeen these aspects with those in animals. Inaddition, this paper is also making exploration of the possible pathway for signal transduction, geneticregulation of plant PCD, origin and evolution of PCD and proposes a tactic for research on plant PCDalthough it is still in a preliminary stage.Compared to PCD in animals, PCD in plants under various conditions has revealed much greaterdifference in morphological and biochemical characteristics, which presents different essence far fromthe definition of apoptosis of animals. Nevertheless, no inflammation, specific fragmentation of DNAand rise of the activities of endonuclease and protease in plant PCD are still typical hallmarks fordistinguishing PCD from necrosis. On view of molecular level, as in animals, PCD in plants is alsoregulated by specific genes and involves signal transduction pathway with the involvement of a varietyof signal molecules.The physiological functions of plant PCD are similar to those in animals too. In the importantphysiological and pathological processes in plants, i.e., during reproduction, development, growth,senescenced disease-resistance, and stress-resistance against adverse circumstance conditions, PCDtakes on functions as important as proliferation throughout the whole life cycle of living organisms.Obviously, the research on PCD in plants is of vital importance that should not be ignored either intheory or in agricultural production.At present, the research on PCD in plants is focusing on collecting morphological and biochemicalevidences. But many molecules of initiation signal participating in plant PCD have been identified andseveral genes directly related to this process were isolated, which provide useful enlightenment forillustrating signal transduction pathway of PCD. Moreover, some conserved signal molecules andregulating genes were found in plant PCD, and caspase-like proteases have been detected in HR celldeath as well as in development-associated PCD. These data provide strong evidence at molecular levelfor conservation and the origin and evolution of PCD.1 The authors want to extend the sincerely thanks to Prof. Michele C. Heath (University of Toronto, Canada),Prof. Niroo Fukuda (University of Tokyo, Japan), Prof. Duran L. Nooden (University of Michigan, USA),Prof. Chris Lamb (Salk institute, California), Prof. Sarah Hake (Agricultural Research Service, USA), Prof.David L. Vaux (The Walter and Eliza Hall insititue of Medical Research, Post Office Royal MelbourneHospital, Australia), Associate Prof. Jeffrey L. Dangl (University of North Carolina, USA), Associate Prof.Eric Lain (The State University of New Jersey, USA), Dr. Maki Katsuhara (Okayama University, Japan),Prof. Sarah Hake (AgricultUral Research Service, USA), Dr. Peter P. Repetti (University of California,USA), Da Blazena Koukalova (Academy of Sciences of the Czech Republic, CZ), Dr. Iona Weir(Horticulture and Food Research Institute of New Zealand, New Zealand), Dr. Thorsten Jabs (Institute forBiology III, Germany), Dr. Hong Wang (University of California, USA) and Dr. Patrick Gallois (Universityof Perpignan, France) for their kind providing their personal latest data of their research concerned andoffering academic exchanges with us.This project is granted by the National Natural Science Foundation of China (No. 39870423) and by StateCommission of Education, Doctorate Spot Foundation.Author for correspondence. E-mail: ycsong@whu.edu.cn.Evidences in various aspects indicate that PCD origins from prokaryote, and various forms of PCD arefound along the phylogenic tree.Conclusion: A variety of endogenous and exogenous signals can break the homeostasis within plantbody and result in differentiation, proliferation, quiescence, or death of cell at length
基金supported by the National Natural Science Foundation of China (NSFC, 31972254)the Fok Ying Tung Education Foundation (171021)+5 种基金the Tianfu Tenthousand Talents Program (Tianfu Science and Technology Elite Project), Chinathe Outstanding Young Scientific and Technological Talents Project in Sichuan Province, China (2019JDJQ0045)Outstanding Youth Science Foundation of Sichuan Agricultural University, China (2021SZYQ002) to Li Weitaothe Key R&D Projects of Science & Technology Department of Sichuan Province (2018JZ0072)NSFC (31825022) to Chen Xueweithe NSFC (32072041) to Yin Junjie。
文摘Cell death is an important physiological phenomenon in life.It can be programmed or unprogrammed.Unprogrammed cell death is usually induced by abiotic or biotic stress.Recent studies have shown that many proteins regulate both cell death and immunity in plants.Here,we provide a review on the advances in plant immunity with cell death,especially the molecular regulation and underlying mechanisms of those proteins involved in both cell death and plant immunity.In addition,we discuss potential approaches toward improving plant immunity without compromising plant growth.
文摘To investigate the changes of tissue transglutaminase activity, the leaves and young panicles of rice at different developmental stages were excised from the Honglian-type cytoplasmic male sterile line, Yuetai A and its maintainer line, Yuetai B, respectively. An ELISA measurement protocol for tissue transglutaminase activity detection in rice was well established. The results indicated that the tissue transglutaminase activity was regulated positively by calcium cation, and the tissue transglutaminase activity in senescent leaves was remarkably higher than that in young leaves. No distinct difference was noted between Yuetai A and Yuetai B. Moreover, from the tetrad to binucleate stages the tissue transglutaminase activity increased gradually with the progression of the young panicle development and up to maximum at binucleate stage in Yuetai A. However, no similar changes were observed in Yuetai B. This indicates that the tissue transglutaminase is involved in cell programmed death in abortive pollen.
文摘The early stage of pollen chamber development in ovule and the cytological mechanism of nucellar cell death were studied in Ginkgo biloba L. DNA ladder appearance and TUNEL assay demonstrated that the nucellar cell death, doomed to bring about pollen chamber formation, was a process of programmed cell death (PCD). A spatial distribution of PCD was visualized during the development of pollen chamber. Together with the observation under the scanning electron microscope, these results have revealed that the early developmental pattern of pollen chamber consists of four phases. Firstly, several layers of the nucellar cells at the micropylar end elongate longitudinally. Thereafter, the uppermost layer of the nucellar cells at the micropylar end initiate PCD; and the nucellar cell death extends in a basally and laterally oriented direction to form a cavity. Finally, the epidermal cells at the micropylar end detach from the other epidermis by dehiscence, bringing about the opening of the pollen chamber. The early development of pollen chamber begins sometime after the stage of megasporocyte and continues by the time of the formation of megaspore tetrad, and finally completes at the stage of development of female gametophyte. This shows a synchronous development of megaspore and pollen chamber.
文摘Abstract: Cell death is a common event in all types of plant organisms. Understanding the phenomenon of programmed cell death (PCD) is an important area of research for plant scientists because of its role in senescence and the post-harvest quality of ornamentals, fruits, and vegetables. In the present paper, PCD in relation to petal senescence in ornamental plants is reviewed. Morphological, anatomical, physiological, and biochemical changes that are related to PCD in petals, such as water content, sink-source relationships, hormones, genes, and signal transduction pathways, are discussed. Several approaches to improving the quality of post-harvest ornamentals are reviewed and some prospects for future research are given.
文摘Programmed cell death (PCD) of the nucellar cells at the micropylar end is involved in pollen chamber morphogenesis in Ginkgo biloba L. A development-course observation of the morphological changes in the nucellar cells undergoing PCD to form pollen chamber was performed. During the PCD, the nucellar cells degraded their cellular components through an orderly progression. Through the vactiolation, the cytosol was engulfed by the enlarging vacuole, leaving out various organelles, which remained morphologically integrated. As the vacuolation continued, the vacuole collapsed with the breakage of the tonoplast and the cytosol disappeared completely. Organelles were subsequently destroyed. Ultimately, nucellar cells digested away all of their cytoplasm, leaving with cell walls. They became collapsed as the nucellus developed. Intracellular membranes were strikingly changed, playing a role in leading to cell death. Some of these noticeable changes were the appearance of multivesicular body, multicycle-like membranes, membrane-bounded bodies containing some organelles, tonoplast rupture and numerous vesicles. The dehiscence of the apical epidermis, resulting in the opening, appeared to have followed two different pathways with one involving a specific epidermal cell autolysis and the other by detachment from middle lamella of two neighboring epidermal cells without cell autolysis. The specific epidermal cells had been dead prior to the dehiscence of the apical epidermis, which marked the sites of the dehiscence followed. In view of the changes in the cellular morphology, a process of nucellar cell PCD in the course of the pollen chamber formation was demonstrated.
基金the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service (No 2002-35301-12234 and 2004-35301-14620)Hatch Act and State of Iowa funds
文摘The maize (Zea mays) spikelet consists of two florets, each of which contains three developmentally synchronized anthers. Morphologically, the anthers in the upper and lower florets proceed through apparently similar developmental programs. To test for global differences in gene expression and to identify genes that are coordinately regulated during maize anther development, RNA samples isolated from upper and lower floret anthers at six developmental stages were hybridized to cDNA microarrays. Approximately 9% of the tested genes exhibited statistically significant differences in expression between anthers in the upper and lower florets. This finding indicates that several basic biological processes are differentially regulated between upper and lower floret anthers, including metabolism, protein synthesis and signal transduction. Genes that are coordinately regulated across anther development were identified via cluster analysis. Analysis of these results identified stage-specific, early in development, late in development and bi-phasic expression profiles. Quantitative RT-PCR analysis revealed that four genes whose homologs in other plant species are involved in programmed cell death are up-regulated just prior to the time the tapetum begins to visibly degenerate (i.e., the mid-microspore stage). This finding supports the hypothesis that developmentally normal tapetal degeneration occurs via programmed cell death.
文摘The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection by biotrophic pathogens, but can, in fact, enhance infection by necrotrophic pathogens like Botrytis cinerea. In addition to signaling the induction of the HR, reactive oxygen species (ROS) produced during the oxidative burst are?antimicrobial. We hypothesize that pathogens such as B. cinerea survive the antimicrobial effects of ROS, at least partially by secreting the antioxidant mannitol during infection. This is supported by the previous observation that overexpression of the catabolic enzyme mannitol dehydrogenase (MTD) can decrease a plants susceptibility to mannitol-secreting pathogens like B. cinerea. To extend the above hypothesis, and test the general utility of this approach in an important horticultural crop, we overexpressed celery MTD in tomato (Solanum lycopersicum cv. “Moneymaker”). In these studies, we observed a significant increase (up to 90%) in resistance to B. cinerea in transgenic tomatoes expressing high amounts of MTD.
基金supported by the National Basic Research Program of China (2012CB114500)the National Natural Science Foundation of China (31070156)
文摘Secondary xylem development has long been recognized as a typical case of programmed cell death (PCD) in plants. During PCD, the degradation of genomic DNA is catalyzed by endonucleases. However, to date, no endonuclease has been shown to participate in secondary xylem development. Two novel Ca^2+-dependent DNase genes, EuCaN1 and EuCaN2, were identified from the differentiating secondary xylem of the tree Eucommia ulmoides Oliv., their functions were studied by DNase activity assay, in situ hybridization, protein immunolocalization and virus-induced gene silencing experiments. Full-length cDNAs of EuCaN1 and EuCaN2 contained an open reading frame of 987 bp, encoding two proteins of 328 amino acids with SNase-like functional domains. The genomic DNA sequence for EuCaN1 had no introns, while EuCaN2 had 8 introns. EuCaN1 and EuCaN2 digested ssDNA and dsDNA with Ca^2+-dependence at neutral pH. Their expression was confined to differentiating secondary xylem cells and the proteins were localized in the nucleus. Their activity dynamics was closely correlated with secondary xylem development. Secondary xylem cell differentiation is influenced by RNAi of endonuclease genes. The results provide evidence that the Ca^2+-dependent DNases are involved in secondary xylem development.
文摘The spatial and temporal distributions of programmed cell death (PCD) in developing central nervous system (CNS) of human fetuses ranging from 12 to 39 weeks of gestation were investigated using techniques of flow cytometry and terminal transferase-mediated nick end labeling (TUNEL). The results showed that PCD did occur in every representative brain region of all fetuses examined in different stages. It was found that there were two peaks of PCD appearing at the 12th and 39th weeks respectively, which suggested that the first peak of apoptosis may be involved in the selective elimination of neurons overproduced during the early development and the second may play an important role in establishing the correct neuronal circuitry.
文摘Sphinganine or dihydrosphingosine (d18:0, DHS), one of the most abundant free sphingoid Long Chain Base (LCB) in plants, has been recently shown to induce both cytosolic and nuclear calcium transient increases and a correlated Programmed Cell Death (PCD) in tobacco BY-2 cells. In this study, in order to get deeper insight into the LCB signaling pathway leading to cell death, the putative role of Reactive Oxygen Species (ROS) has been investigated. We show that DHS triggers a rapid dose-dependent production of H2O2 that is blocked by diphenyleniodonium (DPI), indicating the involvement of NADPH oxidase(s) in the process. In addition, while DPI does not block DHS-induced calcium increases, the ROS production is inhibited by the broad spectrum calcium channel blocker lanthanum (La^3+). Therefore, ROS production occurs downstream of DHS-induced Ca^2+ transients. Interestingly, DHS activates expression of defense-related genes that is inhibited by both La^3+ and DPI. Since DPI does not prevent DHS-induced cell death, these results strongly indicate that DHS-induced H2O2 production is not implicated in PCD mechanisms but rather would be associated to basal cell defense mechanisms.