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Shimon Meir – One of the best experts on this subject based on the ideXlab platform.

  • expression kinetics of regulatory genes involved in the vesicle trafficking processes operating in tomato flower Abscission Zone cells during pedicel Abscission
    Life, 2020
    Co-Authors: Srivignesh Sundaresan, Joseph Riov, Shoshana Salim, Sonia Philosophhadas, Shimon Meir
    Abstract:

    The Abscission process occurs in a specific Abscission Zone (AZ) as a consequence of the middle lamella dissolution, cell wall degradation, and formation of a defense layer. The proteins and metabolites related to these processes are secreted by vesicle trafficking through the plasma membrane to the cell wall and middle lamella of the separating cells in the AZ. We investigated this process, since the regulation of vesicle trafficking in Abscission systems is poorly understood. The data obtained describe, for the first time, the kinetics of the upregulated expression of genes encoding the components involved in vesicle trafficking, occurring specifically in the tomato (Solanum lycopersicum) flower AZ (FAZ) during pedicel Abscission induced by flower removal. The genes encoding vesicle trafficking components included soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), SNARE regulators, and small GTPases. Our results clearly show how the processes of protein secretion by vesicle trafficking are regulated, programmed, and orchestrated at the level of gene expression in the FAZ. The data provide evidence for target proteins, which can be further used for affinity purification of plant vesicles in their natural state. Such analyses and dissection of the complex vesicle trafficking networks are essential for further elucidating the mechanism of organ Abscission.

  • The Tomato Hybrid Proline-rich Protein regulates the Abscission Zone competence to respond to ethylene signals
    Horticulture research, 2018
    Co-Authors: Srivignesh Sundaresan, Sonia Philosoph-hadas, Cai-zhong Jiang, Joseph Riov, Raja Mugasimangalam, Betina Kochanek, Shoshana Salim, Michael S. Reid, Shimon Meir
    Abstract:

    The Tomato Hybrid Proline-rich Protein (THyPRP) gene was specifically expressed in the tomato (Solanum lycopersicum) flower Abscission Zone (FAZ), and its stable antisense silencing under the control of an Abscission Zone (AZ)-specific promoter, Tomato Abscission Polygalacturonase4, significantly inhibited tomato pedicel Abscission following flower removal. For understanding the THyPRP role in regulating pedicel Abscission, a transcriptomic analysis of the FAZ of THyPRP-silenced plants was performed, using a newly developed AZ-specific tomato microarray chip. Decreased expression of THyPRP in the silenced plants was already observed before Abscission induction, resulting in FAZ-specific altered gene expression of transcription factors, epigenetic modifiers, post-translational regulators, and transporters. Our data demonstrate that the effect of THyPRP silencing on pedicel Abscission was not mediated by its effect on auxin balance, but by decreased ethylene biosynthesis and response. Additionally, THyPRP silencing revealed new players, which were demonstrated for the first time to be involved in regulating pedicel Abscission processes. These include: gibberellin perception, Ca2+-Calmodulin signaling, Serpins and Small Ubiquitin-related Modifier proteins involved in post-translational modifications, Synthaxin and SNARE-like proteins, which participate in exocytosis, a process necessary for cell separation. These changes, occurring in the silenced plants early after flower removal, inhibited and/or delayed the acquisition of the competence of the FAZ cells to respond to ethylene signaling. Our results suggest that THyPRP acts as a master regulator of flower Abscission in tomato, predominantly by playing a role in the regulation of the FAZ cell competence to respond to ethylene signals.

  • de novo transcriptome sequencing and development of Abscission Zone specific microarray as a new molecular tool for analysis of tomato organ Abscission
    Frontiers in Plant Science, 2016
    Co-Authors: Srivignesh Sundaresan, Joseph Riov, Raja Mugasimangalam, Shoshana Salim, Sonia Philosophhadas, Bettina Kochanek, Mark L Tucker, Nagesh Aswathnarayana Kuravadi, Shimon Meir
    Abstract:

    Abscission of flower pedicels and leaf petioles of tomato (Solanum lycopersicum) can be induced by flower removal or leaf deblading, respectively, leading to auxin depletion, which results in increased sensitivity of the Abscission Zone (AZ) to ethylene. However, the molecular mechanisms that drive the acquisition of Abscission competence and its modulation by auxin gradients are not yet known. We used RNA-Sequencing (RNA-Seq) to obtain the comprehensive transcriptome of tomato flower AZ (FAZ) and leaf AZ (LAZ) during Abscission. RNA-Seq was performed on a pool of total RNA extracted from different Abscission stages of tomato FAZ and LAZ, followed by de novo assembly. The assembled clusters contained transcripts that are already known in Solanaceae (SOL) genomics database and NCBI databases, and over 8,823 identified novel tomato transcripts of varying sizes. An AZ-specific microarray, encompassing these novel transcripts identified in this study and all known transcripts from the SOL genomics and NCBI databases, was constructed to study the Abscission process. Multiple probes for longer genes and key AZ-specific genes, including antisense probes for all transcripts, make this array a unique tool for studying Abscission with a comprehensive set of transcripts, and for mining for naturally occurring antisense transcripts. We focused on comparing the global transcriptomes generated from the FAZ and the LAZ to establish the divergences and similarities in their transcriptional networks, and particularly to characterize the processes and transcriptional regulators enriched in gene clusters that are differentially regulated in these two AZs. This study is the first attempt to analyze the global gene expression in different AZs in tomato by combining the RNA-Seq technique with oligonucleotide microarrays. Our AZ-specific microarray chip provides a cost-effective approach for expression profiling and robust analysis of multiple samples in a rapid succession.

Srivignesh Sundaresan – One of the best experts on this subject based on the ideXlab platform.

  • expression kinetics of regulatory genes involved in the vesicle trafficking processes operating in tomato flower Abscission Zone cells during pedicel Abscission
    Life, 2020
    Co-Authors: Srivignesh Sundaresan, Joseph Riov, Shoshana Salim, Sonia Philosophhadas, Shimon Meir
    Abstract:

    The Abscission process occurs in a specific Abscission Zone (AZ) as a consequence of the middle lamella dissolution, cell wall degradation, and formation of a defense layer. The proteins and metabolites related to these processes are secreted by vesicle trafficking through the plasma membrane to the cell wall and middle lamella of the separating cells in the AZ. We investigated this process, since the regulation of vesicle trafficking in Abscission systems is poorly understood. The data obtained describe, for the first time, the kinetics of the upregulated expression of genes encoding the components involved in vesicle trafficking, occurring specifically in the tomato (Solanum lycopersicum) flower AZ (FAZ) during pedicel Abscission induced by flower removal. The genes encoding vesicle trafficking components included soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), SNARE regulators, and small GTPases. Our results clearly show how the processes of protein secretion by vesicle trafficking are regulated, programmed, and orchestrated at the level of gene expression in the FAZ. The data provide evidence for target proteins, which can be further used for affinity purification of plant vesicles in their natural state. Such analyses and dissection of the complex vesicle trafficking networks are essential for further elucidating the mechanism of organ Abscission.

  • The Tomato Hybrid Proline-rich Protein regulates the Abscission Zone competence to respond to ethylene signals
    Horticulture research, 2018
    Co-Authors: Srivignesh Sundaresan, Sonia Philosoph-hadas, Cai-zhong Jiang, Joseph Riov, Raja Mugasimangalam, Betina Kochanek, Shoshana Salim, Michael S. Reid, Shimon Meir
    Abstract:

    The Tomato Hybrid Proline-rich Protein (THyPRP) gene was specifically expressed in the tomato (Solanum lycopersicum) flower Abscission Zone (FAZ), and its stable antisense silencing under the control of an Abscission Zone (AZ)-specific promoter, Tomato Abscission Polygalacturonase4, significantly inhibited tomato pedicel Abscission following flower removal. For understanding the THyPRP role in regulating pedicel Abscission, a transcriptomic analysis of the FAZ of THyPRP-silenced plants was performed, using a newly developed AZ-specific tomato microarray chip. Decreased expression of THyPRP in the silenced plants was already observed before Abscission induction, resulting in FAZ-specific altered gene expression of transcription factors, epigenetic modifiers, post-translational regulators, and transporters. Our data demonstrate that the effect of THyPRP silencing on pedicel Abscission was not mediated by its effect on auxin balance, but by decreased ethylene biosynthesis and response. Additionally, THyPRP silencing revealed new players, which were demonstrated for the first time to be involved in regulating pedicel Abscission processes. These include: gibberellin perception, Ca2+-Calmodulin signaling, Serpins and Small Ubiquitin-related Modifier proteins involved in post-translational modifications, Synthaxin and SNARE-like proteins, which participate in exocytosis, a process necessary for cell separation. These changes, occurring in the silenced plants early after flower removal, inhibited and/or delayed the acquisition of the competence of the FAZ cells to respond to ethylene signaling. Our results suggest that THyPRP acts as a master regulator of flower Abscission in tomato, predominantly by playing a role in the regulation of the FAZ cell competence to respond to ethylene signals.

  • de novo transcriptome sequencing and development of Abscission Zone specific microarray as a new molecular tool for analysis of tomato organ Abscission
    Frontiers in Plant Science, 2016
    Co-Authors: Srivignesh Sundaresan, Joseph Riov, Raja Mugasimangalam, Shoshana Salim, Sonia Philosophhadas, Bettina Kochanek, Mark L Tucker, Nagesh Aswathnarayana Kuravadi, Shimon Meir
    Abstract:

    Abscission of flower pedicels and leaf petioles of tomato (Solanum lycopersicum) can be induced by flower removal or leaf deblading, respectively, leading to auxin depletion, which results in increased sensitivity of the Abscission Zone (AZ) to ethylene. However, the molecular mechanisms that drive the acquisition of Abscission competence and its modulation by auxin gradients are not yet known. We used RNA-Sequencing (RNA-Seq) to obtain the comprehensive transcriptome of tomato flower AZ (FAZ) and leaf AZ (LAZ) during Abscission. RNA-Seq was performed on a pool of total RNA extracted from different Abscission stages of tomato FAZ and LAZ, followed by de novo assembly. The assembled clusters contained transcripts that are already known in Solanaceae (SOL) genomics database and NCBI databases, and over 8,823 identified novel tomato transcripts of varying sizes. An AZ-specific microarray, encompassing these novel transcripts identified in this study and all known transcripts from the SOL genomics and NCBI databases, was constructed to study the Abscission process. Multiple probes for longer genes and key AZ-specific genes, including antisense probes for all transcripts, make this array a unique tool for studying Abscission with a comprehensive set of transcripts, and for mining for naturally occurring antisense transcripts. We focused on comparing the global transcriptomes generated from the FAZ and the LAZ to establish the divergences and similarities in their transcriptional networks, and particularly to characterize the processes and transcriptional regulators enriched in gene clusters that are differentially regulated in these two AZs. This study is the first attempt to analyze the global gene expression in different AZs in tomato by combining the RNA-Seq technique with oligonucleotide microarrays. Our AZ-specific microarray chip provides a cost-effective approach for expression profiling and robust analysis of multiple samples in a rapid succession.

Jeremy A. Roberts – One of the best experts on this subject based on the ideXlab platform.

  • the manipulation of auxin in the Abscission Zone cells of arabidopsis flowers reveals that indoleacetic acid signaling is a prerequisite for organ shedding
    Plant Physiology, 2013
    Co-Authors: Manojit Basu, Zinnia H Gonzalezcarranza, S N Azamali, Shouya Tang, Ahmad Ali Shahid, Jeremy A. Roberts
    Abstract:

    A number of novel strategies were employed to examine the role of indoleacetic acid (IAA) in regulating floral organ Abscission in Arabidopsis ( Arabidopsis thaliana ). Analysis of auxin influx facilitator expression in β-glucuronidase reporter plants revealed that AUXIN RESISTANT1 , LIKE AUX1 , and LAX3 were specifically up-regulated at the site of floral organ shedding. Flowers from mutants where individual family members were down-regulated exhibited a reduction in the force necessary to bring about petal separation; however, the effect was not additive in double or quadruple mutants. Using the promoter of a polygalacturonase ( At2g41850 ), active primarily in cells undergoing separation, to drive expression of the bacterial genes iaaL and iaaM , we have shown that it is possible to manipulate auxin activity specifically within the floral organ Abscission Zone (AZ). Analysis of petal breakstrength reveals that if IAAAZ levels are reduced, shedding takes place prematurely, while if they are enhanced, organ loss is delayed. The At2g41850 promoter was also used to transactivate the gain-of-function AXR3-1 gene in order to disrupt auxin signaling specifically within the floral organ AZ cells. Flowers from transactivated lines failed to shed their sepals, petals, and anthers during pod expansion and maturity, and these organs frequently remained attached to the plant even after silique desiccation and dehiscence had taken place. These observations support a key role for IAA in the regulation of Abscission in planta and reveal, to our knowledge for the first time, a requirement for a functional IAA signaling pathway in AZ cells for organ shedding to take place.

  • Characterization and expression of an mRNA encoding a wound-induced (Win) protein from ethylene-treated tomato leaf Abscission Zone tissue
    Journal of Experimental Botany, 1997
    Co-Authors: Neil S. Harris, Jane E. Taylor, Jeremy A. Roberts
    Abstract:

    A cDNA clone (TAB7) encoding a putative wound-induced (Win) protein has been isolated from a tomato (Lycopersicon esculentum Mill. cv. Ailsa Craig) leaf Abscission Zone cDNA library using a differential screening strategy. The clone has a high degree of homology at the amino acid level to both the potato win1 and 2 genes, Hevea brasiliensis hevein and Nicotiana tabacum PR-4a and PR-4b proteins. The mRNA encoded by TAB7 is up-regulated within 12 h of exposure to ethylene (10 μl l -1 ) and its expression increases steadily within the cells comprising the leaf Abscission Zone and to a lesser extent in the adjacent non-Zone tissue. This rise precedes the onset of cell separation. Southern analysis indicates that the mRNA is encoded by either a single gene or a small gene family. The role of the protein during Abscission is discussed.

Emilia Wilmowicz – One of the best experts on this subject based on the ideXlab platform.

  • epip evoked modifications of redox lipid and pectin homeostasis in the Abscission Zone of lupine flowers
    International Journal of Molecular Sciences, 2021
    Co-Authors: Emilia Wilmowicz, Agata Kucko, Wojciech Pokora, Malgorzata Kapusta, Katarzyna Jasienieckagazarkiewicz, Timothy John Tranbarger, Magdalena Wolska, Katarzyna Panek
    Abstract:

    Yellow lupine is a great model for Abscission-related research given that excessive flower abortion reduces its yield. It has been previously shown that the EPIP peptide, a fragment of LlIDL (INFLORESCENCE DEFICIENT IN Abscission) amino-acid sequence, is a sufficient molecule to induce flower abortion, however, the question remains: What are the exact changes evoked by this peptide locally in Abscission Zone (AZ) cells? Therefore, we used EPIP peptide to monitor specific modifications accompanied by early steps of flower Abscission directly in the AZ. EPIP stimulates the downstream elements of the pathway—HAESA and MITOGEN-ACTIVATED PROTEIN KINASE6 and induces cellular symptoms indicating AZ activation. The EPIP treatment disrupts redox homeostasis, involving the accumulation of H2O2 and upregulation of the enzymatic antioxidant system including superoxide dismutase, catalase, and ascorbate peroxidase. A weakening of the cell wall structure in response to EPIP is reflected by pectin demethylation, while a changing pattern of fatty acids and acyl lipids composition suggests a modification of lipid metabolism. Notably, the formation of a signaling molecule—phosphatidic acid is induced locally in EPIP-treated AZ. Collectively, all these changes indicate the switching of several metabolic and signaling pathways directly in the AZ in response to EPIP, which inevitably leads to flower Abscission.

  • Drought Disrupts Auxin Localization in Abscission Zone and Modifies Cell Wall Structure Leading to Flower Separation in Yellow Lupine.
    International journal of molecular sciences, 2020
    Co-Authors: Aleksandra Bogumiła Florkiewicz, Agata Kućko, Małgorzata Kapusta, Sebastian Burchardt, Tomasz Przywieczerski, Grażyna Czeszewska-rosiak, Emilia Wilmowicz
    Abstract:

    Drought causes the excessive Abscission of flowers in yellow lupine, leading to yield loss and serious economic consequences in agriculture. The structure that determines the time of flower shedding is the Abscission Zone (AZ). Its functioning depends on the undisturbed auxin movement from the flower to the stem. However, little is known about the mechanism guiding cell-cell adheadhesion directly in an AZ under water deficit. Therefore, here, we seek a fuller understanding of drought-dependent reactions and check the hypothesis that water limitation in soil disturbs the natural auxin balance within the AZ and, in this way, modifies the cell wall structure, leading to flower separation. Our strategy combined microscopic, biochemical, and chromatography approaches. We show that drought affects indole-3-acetic acid (IAA) distribution and evokes cellular changes, indicating AZ activation and flower abortion. Drought action was manifested by the accumulation of proline in the AZ. Moreover, cell wall-related modifications in response to drought are associated with reorganization of methylated homogalacturonans (HG) in the AZ, and upregulation of pectin methylesterase (PME) and polygalacturonase (PG)-enzymes responsible for pectin remodeling. Another symptom of stress action is the accumulation of hemicelluloses. Our data provide new insights into cell wall remodeling events during drought-induced flower Abscission, which is relevant to control plant production.

  • disruption of the auxin gradient in the Abscission Zone area evokes asymmetrical changes leading to flower separation in yellow lupine
    International Journal of Molecular Sciences, 2020
    Co-Authors: Agata Kucko, Emilia Wilmowicz, Wojciech Pokora, Juan De Dios Alche
    Abstract:

    How auxin transport regulates organ Abscission is a long-standing and intriguing question. Polar auxiauxin transport across the Abscission Zone (AZ) plays a more important role in the regulation of Abscission than a local concentration of this hormone. We recently reported the existence of a spatiotemporal sequential pattern of the indole-3-acetic acid (IAA) localization in the area of the yellow lupine AZ, which is a place of flower detachment. In this study, we performed analyses of AZ following treatment with an inhibitor of polar auxiauxin transport (2,3,5-triiodobenzoic acid (TIBA)). Once we applied TIBA directly onto the AZ, we observed a strong response as demonstrated by enhanced flower Abscission. To elucidate the molecular events caused by the inhibition of auxin movement, we divided the AZ into the distal and proximal part. TIBA triggered the formation of the IAA gradient between these two parts. The AZ-marker genes, which encode the downstream molecular components of the inflorescence deficient in Abscission (IDA)-signaling system executing the Abscission, were expressed in the distal part. The accumulation of IAA in the proximal area accelerated the biosynthesis of abscisic acid and ethylene (stimulators of flower separation), which was also reflected at the transcriptional level. Accumulated IAA up-regulated reactive oxygen species (ROS) detoxification mechanisms. Collectively, we provide new information regarding auxin-regulated processes operating in specific areas of the AZ.

Amnon Lers – One of the best experts on this subject based on the ideXlab platform.

  • The pattern of 1-aminocyclopropane-1-carboxylate oxidase induction in the tomato leaf petiole Abscission Zone is independent of expression of the ribonuclease-LX-encoding LeLX gene.
    Plant biology (Stuttgart Germany), 2018
    Co-Authors: Marko Chersicola, Aleš Kladnik, M. Tušek Žnidarič, Amnon Lers, Marina Dermastia
    Abstract:

    The Abscission of tomato leaves occurs in the petiole Abscission Zone, and its late stage includes two spatially divided processes: cell separation and programmed cell death (PCD). Both of these processes are regulated by ethylene. The last step in ethylene biosynthesis is conversion of 1-aminocyclopropane-1-carboxylic acid to ethylene, which is catalysed by the enzyme 1-aminocyclopropane-1-carboxylate oxidase (ACO); however, the location of ACO in the leaf petiole Abscission Zone is not known. The tomato gene LeLX encodes ribonuclease LX, which is a marker for PCD and is induced by ethylene during Abscission, but its association with ACO has not been explored. In a tomato transgenic line 1-7 with inhibited expression of LeLX showing delayed leaf Abscission, the morphology and ultrastructure of the leaf petiole Abscission Zone was examined. In this Zone of the cv.’VF36′ and of a transgenic line 1-7, spatiotemporal differences in expression of LeACO1 and LeACO4 were analysed and ACO protein was detected immunohistochemically. In comparison to wild-type plants, there were no obvious morphological and ultrastructural features in the Abscission Zone of plants of a transgenic line 1-7 before and after Abscission induction. LeACO1 expression was low before Abscission induction, and increased 24 h after induction, although with no apparent spatial pattern. In contrast, LeACO4 was expressed before Abscission induction, and its transcript level declined 24 h after induction on the distal side of the Abscission Zone fracture. In the LeLX-inhibited transgenic line, there were no significant differences in LeACO1 and LeACO4 expression in the petiole Abscission Zone, in comparison to wild-type plants. In addition, the ACO protein was immunolocalised to the vascular tissues that traverse the petiole Abscission Zone in plants of wild type and of a transgenic line 1-7; and additionally in the plane of future Abscission Zone fracture of transgenic-line plants. The results suggest temporal differential expression of the LeACO genes in tomato leaf petioles and vascular localisation of ACO1 protein. Additionally, the results indicate that expression of LeACO genes is not affected by suppression of the LeLX expression.

  • Endoreduplication preferentially occurs at the proximal side of the Abscission Zone during Abscission of tomato leaf
    Plant signaling & behavior, 2012
    Co-Authors: Marina Dermastia, Aleš Kladnik, Tal Bar-dror, Amnon Lers
    Abstract:

    Endoreduplication is a cell cycle variant in which multiple rounds of DNA replication occur without subsequent mitosis, resulting in polyploid cells. Although cells with endoreduplicated nuclei were ubiquitously distributed throughout the Abscission Zone (AZ) of tomato leaf before Abscission induction by ethylene, endoreduplication was detected mostly on the proximal side of the AZ after induction. The possible association between endoreduplication and intensive membrane trafficking in cells at the proximal side of the AZ is discussed.

  • microarray analysis of the Abscission related transcriptome in the tomato flower Abscission Zone in response to auxin depletion
    Plant Physiology, 2010
    Co-Authors: Shimon Meir, Srivignesh Sundaresan, Cai-zhong Jiang, Michael S. Reid, Sonia Philosophhadas, K Vijay S Selvaraj, Shaul Burd, Ron Ophir, Bettina Kochanek, Amnon Lers
    Abstract:

    The Abscission process is initiated by changes in the auxin gradient across the Abscission Zone (AZ) and is triggered by ethylene. Although changes in gene expression have been correlated with the ethylene-mediated execution of Abscission, there is almost no information on the molecular and biochemical basis of the increased AZ sensitivity to ethylene. We examined transcriptome changes in the tomato (Solanum lycopersicum ‘Shiran 1335’) flower AZ during the rapid acquisition of ethylene sensitivity following flower removal, which depletes the AZ from auxin, with or without preexposure to 1-methylcyclopropene or application of indole-3-acetic acid after flower removal. Microarray analysis using the Affymetrix Tomato GeneChip revealed changes in expression, occurring prior to and during pedicel Abscission, of many genes with possible regulatory functions. They included a range of auxin- and ethylene-related transcription factors, other transcription factors and regulatory genes that are transiently induced early, 2 h after flower removal, and a set of novel AZ-specific genes. All gene expressions initiated by flower removal and leading to pedicel Abscission were inhibited by indole-3-acetic acid application, while 1-methylcyclopropene pretreatment inhibited only the ethylene-induced expressions, including those induced by wound-associated ethylene signals. These results confirm our hypothesis that acquisition of ethylene sensitivity in the AZ is associated with altered expression of auxin-regulated genes resulting from auxin depletion. Our results shed light on the regulatory control of Abscission at the molecular level and further expand our knowledge of auxin-ethylene cross talk during the initial controlling stages of the process.