The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
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, 2020Co-Authors: Srivignesh Sundaresan, Joseph Riov, Shoshana Salim, Sonia Philosophhadas, Shimon MeirAbstract: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, 2018Co-Authors: Srivignesh Sundaresan, Sonia Philosoph-hadas, Cai-zhong Jiang, Joseph Riov, Raja Mugasimangalam, Betina Kochanek, Shoshana Salim, Michael S. Reid, Shimon MeirAbstract: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, 2016Co-Authors: Srivignesh Sundaresan, Joseph Riov, Raja Mugasimangalam, Shoshana Salim, Sonia Philosophhadas, Bettina Kochanek, Mark L Tucker, Nagesh Aswathnarayana Kuravadi, Shimon MeirAbstract: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.
-
Abscission of flowers and floral organs is closely associated with alkalization of the cytosol in Abscission Zone cells
Journal of Experimental Botany, 2015Co-Authors: Srivignesh Sundaresan, Joseph Riov, Betina Kochanek, Sonia Philosophhadas, Eduard Belausov, Mark L Tucker, Shimon MeirAbstract:In vivo changes in the cytosolic pH of Abscission Zone (AZ) cells were visualized using confocal microscopic detection of the fluorescent pH-sensitive and intracellularly trapped dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF), driven by its acetoxymethyl ester. A specific and gradual increase in the cytosolic pH of AZ cells was observed during natural Abscission of flower organs in Arabidopsis thaliana and wild rocket (Diplotaxis tenuifolia), and during flower pedicel Abscission induced by flower removal in tomato (Solanum lycopersicum Mill). The alkalization pattern in the first two species paralleled the acceleration or inhibition of flower organ Abscission induced by ethylene or its inhibitor 1-methylcyclopropene (1-MCP), respectively. Similarly, 1-MCP pre-treatment of tomato inflorescence explants abolished the pH increase in AZ cells and pedicel Abscission induced by flower removal. Examination of the pH changes in the AZ cells of Arabidopsis mutants defective in both ethylene-induced (ctr1, ein2, eto4) and ethylene-independent (ida, nev7, dab5) Abscission pathways confirmed these results. The data indicate that the pH changes in the AZ cells are part of both the ethylene-sensitive and -insensitive Abscission pathways, and occur concomitantly with the execution of organ Abscission. pH can affect enzymatic activities and/or act as a signal for gene expression. Changes in pH during Abscission could occur via regulation of transporters in AZ cells, which might affect cytosolic pH. Indeed, four genes associated with pH regulation, vacuolar H(+)-ATPase, putative high-affinity nitrate transporter, and two GTP-binding proteins, were specifically up-regulated in tomato flower AZ following Abscission induction, and 1-MCP reduced or abolished the increased expression.
-
microarray analysis of the Abscission related transcriptome in the tomato flower Abscission Zone in response to auxin depletion
Plant Physiology, 2010Co-Authors: Shimon Meir, Srivignesh Sundaresan, Cai-zhong Jiang, Michael S. Reid, Sonia Philosophhadas, K Vijay S Selvaraj, Shaul Burd, Ron Ophir, Bettina Kochanek, Amnon LersAbstract: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.
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, 2020Co-Authors: Srivignesh Sundaresan, Joseph Riov, Shoshana Salim, Sonia Philosophhadas, Shimon MeirAbstract: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, 2018Co-Authors: Srivignesh Sundaresan, Sonia Philosoph-hadas, Cai-zhong Jiang, Joseph Riov, Raja Mugasimangalam, Betina Kochanek, Shoshana Salim, Michael S. Reid, Shimon MeirAbstract: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, 2016Co-Authors: Srivignesh Sundaresan, Joseph Riov, Raja Mugasimangalam, Shoshana Salim, Sonia Philosophhadas, Bettina Kochanek, Mark L Tucker, Nagesh Aswathnarayana Kuravadi, Shimon MeirAbstract: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.
-
Abscission of flowers and floral organs is closely associated with alkalization of the cytosol in Abscission Zone cells
Journal of Experimental Botany, 2015Co-Authors: Srivignesh Sundaresan, Joseph Riov, Betina Kochanek, Sonia Philosophhadas, Eduard Belausov, Mark L Tucker, Shimon MeirAbstract:In vivo changes in the cytosolic pH of Abscission Zone (AZ) cells were visualized using confocal microscopic detection of the fluorescent pH-sensitive and intracellularly trapped dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF), driven by its acetoxymethyl ester. A specific and gradual increase in the cytosolic pH of AZ cells was observed during natural Abscission of flower organs in Arabidopsis thaliana and wild rocket (Diplotaxis tenuifolia), and during flower pedicel Abscission induced by flower removal in tomato (Solanum lycopersicum Mill). The alkalization pattern in the first two species paralleled the acceleration or inhibition of flower organ Abscission induced by ethylene or its inhibitor 1-methylcyclopropene (1-MCP), respectively. Similarly, 1-MCP pre-treatment of tomato inflorescence explants abolished the pH increase in AZ cells and pedicel Abscission induced by flower removal. Examination of the pH changes in the AZ cells of Arabidopsis mutants defective in both ethylene-induced (ctr1, ein2, eto4) and ethylene-independent (ida, nev7, dab5) Abscission pathways confirmed these results. The data indicate that the pH changes in the AZ cells are part of both the ethylene-sensitive and -insensitive Abscission pathways, and occur concomitantly with the execution of organ Abscission. pH can affect enzymatic activities and/or act as a signal for gene expression. Changes in pH during Abscission could occur via regulation of transporters in AZ cells, which might affect cytosolic pH. Indeed, four genes associated with pH regulation, vacuolar H(+)-ATPase, putative high-affinity nitrate transporter, and two GTP-binding proteins, were specifically up-regulated in tomato flower AZ following Abscission induction, and 1-MCP reduced or abolished the increased expression.
-
microarray analysis of the Abscission related transcriptome in the tomato flower Abscission Zone in response to auxin depletion
Plant Physiology, 2010Co-Authors: Shimon Meir, Srivignesh Sundaresan, Cai-zhong Jiang, Michael S. Reid, Sonia Philosophhadas, K Vijay S Selvaraj, Shaul Burd, Ron Ophir, Bettina Kochanek, Amnon LersAbstract: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.
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, 2013Co-Authors: Manojit Basu, Zinnia H Gonzalezcarranza, S N Azamali, Shouya Tang, Ahmad Ali Shahid, Jeremy A. RobertsAbstract: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, 1997Co-Authors: Neil S. Harris, Jane E. Taylor, Jeremy A. RobertsAbstract: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, 2021Co-Authors: Emilia Wilmowicz, Agata Kucko, Wojciech Pokora, Malgorzata Kapusta, Katarzyna Jasienieckagazarkiewicz, Timothy John Tranbarger, Magdalena Wolska, Katarzyna PanekAbstract: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, 2020Co-Authors: Aleksandra Bogumiła Florkiewicz, Agata Kućko, Małgorzata Kapusta, Sebastian Burchardt, Tomasz Przywieczerski, Grażyna Czeszewska-rosiak, Emilia WilmowiczAbstract: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 adhesion 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, 2020Co-Authors: Agata Kucko, Emilia Wilmowicz, Wojciech Pokora, Juan De Dios AlcheAbstract:How auxin transport regulates organ Abscission is a long-standing and intriguing question. Polar auxin 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 auxin 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.
-
gibberellic acid affects the functioning of the flower Abscission Zone in lupinus luteus via cooperation with the ethylene precursor independently of abscisic acid
Journal of Plant Physiology, 2018Co-Authors: Katarzyna Marciniak, Emilia Wilmowicz, Agata Kucko, Michal świdzinski, Krzysztof Przedniczek, Jan KopcewiczAbstract:The Abscission of plant organs is a phytohormone-controlled process. Our study provides new insight into the involvement of gibberellic acid (GA3) in the functioning of the flower Abscission Zone (AZ) in yellow lupine (Lupinus luteus L.). Physiological studies demonstrated that GA3 stimulated flower abortion. Additionally, this phytohormone was abundantly presented in the AZ cells of naturally abscised flowers, especially in vascular bundles. Interesting interactions among GA3 and other modulators of flower separation were also investigated. GA3 accumulated after treatment with the ethylene (ET) precursor 1-aminocyclopropane-1-carboxylic acid (ACC). Abscisic acid (ABA) treatment did not cause such an effect. Furthermore, the expression of the newly identified LlGA20ox1 and LlGA2ox1 genes encoding 2-oxoglutarate-dependent dioxygenases fluctuated after ACC or ABA treatment which confirmed the existence of regulatory crosstalk. GA3 appears to cooperate with the ET precursor in the regulation of AZ function in L. luteus flowers; however, the presented mechanism is ABA-independent.
-
the influence of abscisic acid on the ethylene biosynthesis pathway in the functioning of the flower Abscission Zone in lupinus luteus
Journal of Plant Physiology, 2016Co-Authors: Emilia Wilmowicz, Kamil Frankowski, Agata Kucko, Michal świdzinski, Juan De Dios Alche, Anna Nowakowska, Jan KopcewiczAbstract:Flower Abscission is a highly regulated developmental process activated in response to exogenous (e.g. changing environmental conditions) and endogenous stimuli (e.g. phytohormones). Ethylene (ET) and abscisic acid (ABA) are very effective stimulators of flower abortion in Lupinus luteus, which is a widely cultivated species in Poland, Australia and Mediterranean countries. In this paper, we show that artificial activation of Abscission by flower removal caused an accumulation of ABA in the Abscission Zone (AZ). Moreover, the blocking of that phytohormone's biosynthesis by NDGA (nordihydroguaiaretic acid) decreased the number of abscised flowers. However, the application of NBD - an inhibitor of ET action - reversed the stimulatory effect of ABA on flower Abscission, indicating that ABA itself is not sufficient to turn on the organ separation. Our analysis revealed that exogenous ABA significantly accelerated the transcriptional activity of the ET biosynthesis genes ACC synthase (LlACS) and oxidase (LlACO), and moreover, strongly increased the level of 1-aminocyclopropane-1-carboxylic acid (ACC) - ET precursor, which was specifically localized within AZ cells. We cannot exclude the possibility that ABA mediates flower Abscission processes by enhancing the ET biosynthesis rate. The findings of our study will contribute to the overall basic knowledge on the phytohormone-regulated generative organs Abscission in L. luteus.
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), 2018Co-Authors: Marko Chersicola, Aleš Kladnik, M. Tušek Žnidarič, Amnon Lers, Marina DermastiaAbstract: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, 2012Co-Authors: Marina Dermastia, Aleš Kladnik, Tal Bar-dror, Amnon LersAbstract: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, 2010Co-Authors: Shimon Meir, Srivignesh Sundaresan, Cai-zhong Jiang, Michael S. Reid, Sonia Philosophhadas, K Vijay S Selvaraj, Shaul Burd, Ron Ophir, Bettina Kochanek, Amnon LersAbstract: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.
