The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Gregorio Hueros - One of the best experts on this subject based on the ideXlab platform.
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Cell wall invertase activity regulates the expression of the Transfer Cell-specific transcription factor ZmMRP-1.
Planta, 2017Co-Authors: Diego Bergareche, Joaquín Royo, Luis M. Muñiz, Gregorio HuerosAbstract:Main conclusion Studies in Cell wall bound invertase mutants indicate that the promoter of the Transfer Cell-specific transcription factor, ZmMRP - 1 , is modulated by the carbohydrate balance. Transfer Cells are highly specialized plant Cells located at the surfaces that need to support an intensive exchange of nutrients, such as the entrance of fruits, seeds and nodules or the young branching points along the stem. ZmMRP-1 is a one-domain MYB-related transcription factor specifically expressed at the Transfer Cell layer of the maize endosperm. Previous studies demonstrated that this factor regulates the expression of a large number of Transfer Cell-specific genes, and suggested that ZmMRP-1 is a key regulator of the differentiation of this tissue. The expression of this gene is largely dominated by positional cues, but within the ZmMRP-1 expressing Cells the promoter appears to be modulated by sugars. Here we have investigated in vivo this modulation. Using maize and Arabidopsis mutants for Cell wall invertase genes, we found that the absence of Cell wall invertase activity is a major inductive signal of the ZmMRP-1 expression.
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Transcriptional activation of the maize endosperm Transfer Cell-specific gene BETL1 by ZmMRP-1 is enhanced by two C_2H_2 zinc finger-containing proteins
Planta, 2009Co-Authors: Joaquín Royo, Elisa Gómez, Cristina Barrero, Luis Miguel Muñiz, Yolanda Sanz, Gregorio HuerosAbstract:ZmMRP-1 is a single MYB-domain transcription factor specifically expressed in the Transfer Cell layer of the maize endosperm, where it directly regulates the expression of a number of Transfer Cell specific genes and very likely contributes to the regulation of the Transfer Cell differentiation process. It is still a matter of debate, however, how this type of transcription factors interact with the promoter sequences they regulate. In this work we have investigated the existence of proteins interacting with ZmMRP-1 in the Transfer Cell nuclei. In a yeast double-hybrid screen we identified two related maize proteins, ZmMRPI-1 and ZmMRPI-2 belonging to the C_2H_2 zinc finger protein family, which interact with ZmMRP-1 and modulate its activity on Transfer Cell specific promoters. Two ZmMRPI orthologous genes were also identified in the rice and Arabidopsis genomes. The expression pattern in maize and Arabidopsis suggest a role for these proteins in gene regulation at the exchange surfaces where ZmMRP-1 is expressed providing the first indication of their function. We show that this previously uncharacterized family of proteins encodes nuclear proteins that interact with MYB-related transcription factors through their C-terminal conserved domain.
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the maize transcription factor myb related protein 1 is a key regulator of the differentiation of Transfer Cells
The Plant Cell, 2009Co-Authors: Elisa Gómez, Joaquín Royo, Luis M. Muñiz, Cristina Barrero, Wyatt Paul, Pascual Perez, Olivier Sellam, Denise Gerentes, Maribel Lopez, Gregorio HuerosAbstract:Transfer Cells are highly modified plant Cells specialized in the transport of solutes. They differentiate at many plant exchange surfaces, including phloem loading and unloading zones such as those present in the sink organs and seeds. In maize (Zea mays) seeds, Transfer Cells are located at the base of the endosperm. It is currently unknown how apical-basal polarity is established or why the peripheral Cells at the base of the endosperm differentiate into Transfer instead of aleurone Cells. Here, we show that in epidermal Cells committed to develop into aleurone Cells, the ectopic expression of the Transfer Cell-specific transcriptional activator Myb-Related Protein-1 (MRP-1) is sufficient to temporarily transform them into Transfer Cells. These transformed Cells acquire distinct Transfer Cell features, such as Cell wall ingrowths and an elongated shape. In addition, they express a number of MRP-1 target genes presumably involved in defense. We also show that the expression of MRP-1 is needed to maintain the Transfer Cell phenotype. Later in development, an observed reduction in the ectopic expression of MRP-1 was followed by the reversion of the transformed Cells, which then acquire aleurone Cell features.
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The promoter of ZmMRP-1, a maize Transfer Cell-specific transcriptional activator, is induced at solute exchange surfaces and responds to transport demands
Planta, 2009Co-Authors: Cristina Barrero, Joaquín Royo, Carmen Grijota-martinez, Christian Faye, Wyatt Paul, Soledad Sanz, H.-h. Steinbiss, Gregorio HuerosAbstract:Transfer Cells have specializations that facilitate the transport of solutes across plant exchange surfaces. ZmMRP-1 is a maize ( Zea mays ) endosperm Transfer Cell-specific transcriptional activator that plays a central role in the regulatory pathways controlling Transfer Cell differentiation and function. The present work investigates the signals controlling the expression of ZmMRP-1 through the production of transgenic lines of maize, Arabidopsis , tobacco and barley containing ZmMRP-1promoter:GUS reporter constructs. The GUS signal predominantly appeared in regions of active transport between source and sink tissues, including nematode-induced feeding structures and at sites of vascular connection between developing organs and the main plant vasculature. In those cases, promoter induction was associated with the initial developmental stages of transport structures. Significantly, Transfer Cells also differentiated in these regions suggesting that, independent of species, location or morphological features, Transfer Cells might differentiate in a similar way under the influence of conserved induction signals. In planta and yeast experiments showed that the promoter activity is modulated by carbohydrates, glucose being the most effective inducer.
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Molecular dissection of the interaction between the transcriptional activator ZmMRP-1 and the promoter of BETL-1
Plant Molecular Biology, 2006Co-Authors: Cristina Barrero, Elisa Gómez, Gregorio Hueros, Luis M. Muñiz, Joaquín RoyoAbstract:The interaction between the Transfer Cell specific transcriptional activator ZmMRP-1 and the promoter of the Transfer Cell specific gene BETL-1 constitutes an exceptionally robust system. Reporter constructs containing the BETL-1 promoter are virtually silent in a variety of Cell types, from maize leaves to yeast. The introduction of ZmMRP-1 in co-transformation assays leads to the transactivation of the reporter construct by up to two orders of magnitude. In this work we have investigated the molecular basis of this interaction. We found that the BETL-1 promoter includes four potential targets for ZmMRP-1 binding, consisting of a 12 bp motif containing two repeats. Co-transformation assays and electrophoretic mobility shift experiments identified the sequence TATCTCTATCTC as the preferred one for the interaction with the transcription factor. Identification of similar sequences in other Transfer Cell specific promoters lead us to propose as a Transfer Cell box a sequence related to those identified in the BETL-1 promoter, positioned 50–100 bp upstream the TATA box.
Joaquín Royo - One of the best experts on this subject based on the ideXlab platform.
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Cell wall invertase activity regulates the expression of the Transfer Cell-specific transcription factor ZmMRP-1.
Planta, 2017Co-Authors: Diego Bergareche, Joaquín Royo, Luis M. Muñiz, Gregorio HuerosAbstract:Main conclusion Studies in Cell wall bound invertase mutants indicate that the promoter of the Transfer Cell-specific transcription factor, ZmMRP - 1 , is modulated by the carbohydrate balance. Transfer Cells are highly specialized plant Cells located at the surfaces that need to support an intensive exchange of nutrients, such as the entrance of fruits, seeds and nodules or the young branching points along the stem. ZmMRP-1 is a one-domain MYB-related transcription factor specifically expressed at the Transfer Cell layer of the maize endosperm. Previous studies demonstrated that this factor regulates the expression of a large number of Transfer Cell-specific genes, and suggested that ZmMRP-1 is a key regulator of the differentiation of this tissue. The expression of this gene is largely dominated by positional cues, but within the ZmMRP-1 expressing Cells the promoter appears to be modulated by sugars. Here we have investigated in vivo this modulation. Using maize and Arabidopsis mutants for Cell wall invertase genes, we found that the absence of Cell wall invertase activity is a major inductive signal of the ZmMRP-1 expression.
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Transcriptional activation of the maize endosperm Transfer Cell-specific gene BETL1 by ZmMRP-1 is enhanced by two C_2H_2 zinc finger-containing proteins
Planta, 2009Co-Authors: Joaquín Royo, Elisa Gómez, Cristina Barrero, Luis Miguel Muñiz, Yolanda Sanz, Gregorio HuerosAbstract:ZmMRP-1 is a single MYB-domain transcription factor specifically expressed in the Transfer Cell layer of the maize endosperm, where it directly regulates the expression of a number of Transfer Cell specific genes and very likely contributes to the regulation of the Transfer Cell differentiation process. It is still a matter of debate, however, how this type of transcription factors interact with the promoter sequences they regulate. In this work we have investigated the existence of proteins interacting with ZmMRP-1 in the Transfer Cell nuclei. In a yeast double-hybrid screen we identified two related maize proteins, ZmMRPI-1 and ZmMRPI-2 belonging to the C_2H_2 zinc finger protein family, which interact with ZmMRP-1 and modulate its activity on Transfer Cell specific promoters. Two ZmMRPI orthologous genes were also identified in the rice and Arabidopsis genomes. The expression pattern in maize and Arabidopsis suggest a role for these proteins in gene regulation at the exchange surfaces where ZmMRP-1 is expressed providing the first indication of their function. We show that this previously uncharacterized family of proteins encodes nuclear proteins that interact with MYB-related transcription factors through their C-terminal conserved domain.
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the maize transcription factor myb related protein 1 is a key regulator of the differentiation of Transfer Cells
The Plant Cell, 2009Co-Authors: Elisa Gómez, Joaquín Royo, Luis M. Muñiz, Cristina Barrero, Wyatt Paul, Pascual Perez, Olivier Sellam, Denise Gerentes, Maribel Lopez, Gregorio HuerosAbstract:Transfer Cells are highly modified plant Cells specialized in the transport of solutes. They differentiate at many plant exchange surfaces, including phloem loading and unloading zones such as those present in the sink organs and seeds. In maize (Zea mays) seeds, Transfer Cells are located at the base of the endosperm. It is currently unknown how apical-basal polarity is established or why the peripheral Cells at the base of the endosperm differentiate into Transfer instead of aleurone Cells. Here, we show that in epidermal Cells committed to develop into aleurone Cells, the ectopic expression of the Transfer Cell-specific transcriptional activator Myb-Related Protein-1 (MRP-1) is sufficient to temporarily transform them into Transfer Cells. These transformed Cells acquire distinct Transfer Cell features, such as Cell wall ingrowths and an elongated shape. In addition, they express a number of MRP-1 target genes presumably involved in defense. We also show that the expression of MRP-1 is needed to maintain the Transfer Cell phenotype. Later in development, an observed reduction in the ectopic expression of MRP-1 was followed by the reversion of the transformed Cells, which then acquire aleurone Cell features.
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The promoter of ZmMRP-1, a maize Transfer Cell-specific transcriptional activator, is induced at solute exchange surfaces and responds to transport demands
Planta, 2009Co-Authors: Cristina Barrero, Joaquín Royo, Carmen Grijota-martinez, Christian Faye, Wyatt Paul, Soledad Sanz, H.-h. Steinbiss, Gregorio HuerosAbstract:Transfer Cells have specializations that facilitate the transport of solutes across plant exchange surfaces. ZmMRP-1 is a maize ( Zea mays ) endosperm Transfer Cell-specific transcriptional activator that plays a central role in the regulatory pathways controlling Transfer Cell differentiation and function. The present work investigates the signals controlling the expression of ZmMRP-1 through the production of transgenic lines of maize, Arabidopsis , tobacco and barley containing ZmMRP-1promoter:GUS reporter constructs. The GUS signal predominantly appeared in regions of active transport between source and sink tissues, including nematode-induced feeding structures and at sites of vascular connection between developing organs and the main plant vasculature. In those cases, promoter induction was associated with the initial developmental stages of transport structures. Significantly, Transfer Cells also differentiated in these regions suggesting that, independent of species, location or morphological features, Transfer Cells might differentiate in a similar way under the influence of conserved induction signals. In planta and yeast experiments showed that the promoter activity is modulated by carbohydrates, glucose being the most effective inducer.
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Molecular dissection of the interaction between the transcriptional activator ZmMRP-1 and the promoter of BETL-1
Plant Molecular Biology, 2006Co-Authors: Cristina Barrero, Elisa Gómez, Gregorio Hueros, Luis M. Muñiz, Joaquín RoyoAbstract:The interaction between the Transfer Cell specific transcriptional activator ZmMRP-1 and the promoter of the Transfer Cell specific gene BETL-1 constitutes an exceptionally robust system. Reporter constructs containing the BETL-1 promoter are virtually silent in a variety of Cell types, from maize leaves to yeast. The introduction of ZmMRP-1 in co-transformation assays leads to the transactivation of the reporter construct by up to two orders of magnitude. In this work we have investigated the molecular basis of this interaction. We found that the BETL-1 promoter includes four potential targets for ZmMRP-1 binding, consisting of a 12 bp motif containing two repeats. Co-transformation assays and electrophoretic mobility shift experiments identified the sequence TATCTCTATCTC as the preferred one for the interaction with the transcription factor. Identification of similar sequences in other Transfer Cell specific promoters lead us to propose as a Transfer Cell box a sequence related to those identified in the BETL-1 promoter, positioned 50–100 bp upstream the TATA box.
John W. Patrick - One of the best experts on this subject based on the ideXlab platform.
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A Structurally Specialized Uniform Wall Layer is Essential for Constructing Wall Ingrowth Papillae in Transfer Cells.
Frontiers in plant science, 2017Co-Authors: Xue Xia, Christina E. Offler, Hui-ming Zhang, John W. PatrickAbstract:Transfer Cells are characterized by wall labyrinths with either a flange or reticulate architecture. A literature survey established that reticulate wall ingrowth papillae ubiquitously arise from a modified component of their wall labyrinth, termed the uniform wall layer; a structure absent from flange Transfer Cells. This finding sparked an investigation of the deposition characteristics and role of the uniform wall layer using a Vicia faba cotyledon culture system. On Transfer of cotyledons to culture, their adaxial epidermal Cells spontaneously trans-differentiate to a reticulate architecture comparable to their abaxial epidermal Transfer Cell counterparts formed in planta. Uniform wall layer construction commenced once adaxial epidermal Cell expansion had ceased to overlay the original outer periclinal wall on its inner surface. In contrast to the dense ring-like lattice of Cellulose microfibrils in the original primary wall, the uniform wall layer was characterized by a sparsely dispersed array of linear Cellulose microfibrils. A re-modelled cortical microtubule array exerted no influence on uniform wall layer formation or on its Cellulose microfibril organization. Surprisingly, formation of the uniform wall layer was not dependent upon depositing a Cellulose scaffold. In contrast, uniform wall Cellulose microfibrils were essential precursors for constructing wall ingrowth papillae. On converging to form wall ingrowth papillae, the Cellulose microfibril diameters increased three-fold. This event correlated with up-regulated differential, and Transfer-Cell specific, expression of VfCesA3B while transcript levels of other Cellulose biosynthetic-related genes linked with primary wall construction were substantially down regulated.
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Differential transcriptional networks associated with key phases of ingrowth wall construction in trans-differentiating epidermal Transfer Cells of Vicia faba cotyledons
BMC Plant Biology, 2015Co-Authors: Hui-ming Zhang, Christina E. Offler, Simon Wheeler, Xue Xia, Ruslana Radchuk, Hans Weber, John W. PatrickAbstract:Background Transfer Cells are characterized by intricate ingrowth walls, comprising an uniform wall upon which wall ingrowths are deposited. The ingrowth wall forms a scaffold to support an amplified plasma membrane surface area enriched in membrane transporters that collectively confers Transfer Cells with an enhanced capacity for membrane transport at bottlenecks for apo-/symplasmic exchange of nutrients. However, the underlying molecular mechanisms regulating polarized construction of the ingrowth wall and membrane transporter profile are poorly understood. Results An RNAseq study of an inducible epidermal Transfer Cell system in cultured Vicia faba cotyledons identified Transfer Cell specific transcriptomes associated with uniform wall and wall ingrowth deposition. All functional groups of genes examined were expressed before and following transition to a Transfer Cell fate. What changed were the isoform profiles of expressed genes within functional groups. Genes encoding ethylene and Ca^2+ signal generation and transduction pathways were enriched during uniform wall construction. Auxin-and reactive oxygen species-related genes dominated during wall ingrowth formation and ABA genes were evenly expressed across ingrowth wall construction. Expression of genes encoding kinesins, formins and villins was consistent with reorganization of cytoskeletal components. Uniform wall and wall ingrowth specific expression of exocyst complex components and SNAREs suggested specific patterns of exocytosis while dynamin mediated endocytotic activity was consistent with establishing wall ingrowth loci. Key regulatory genes of biosynthetic pathways for sphingolipids and sterols were expressed across ingrowth wall construction. Transfer Cell specific expression of Cellulose synthases was absent. Rather xyloglucan, xylan and pectin biosynthetic genes were selectively expressed during uniform wall construction. More striking was expression of genes encoding enzymes for re-modelling/degradation of Cellulose, xyloglucans, pectins and callose. Extensins dominated the cohort of expressed wall structural proteins and particularly so across wall ingrowth development. Ion transporters were selectively expressed throughout ingrowth wall development along with organic nitrogen transporters and a large group of ABC transporters. Sugar transporters were less represented. Conclusions Pathways regulating signalling and intraCellular organization were fine tuned whilst Cell wall construction and membrane transporter profiles were altered substantially upon transiting to a Transfer Cell fate. Each phase of ingrowth wall construction was linked with unique cohorts of expressed genes.
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Role of sugars in regulating Transfer Cell development in cotyledons of developing Vicia faba seeds.
Protoplasma, 2006Co-Authors: T. Wardini, Christina E. Offler, Mark J Talbot, John W. PatrickAbstract:Transfer Cell formation in cotyledons of developing faba bean (Vicia faba L.) seeds coincides with an abrupt change in seed apoplasm composition from one dominated by hexoses to one in which sucrose is the principal sugar. On the basis of these observations, we tested the hypothesis that sugars induce and/or sustain Transfer Cell development. To avoid confounding effects of in planta developmental programs, we exploited the finding that adaxial epidermal Cells of cotyledons, which do not become Transfer Cells in planta, can be induced to form functional Transfer Cells when cotyledons are cultured on an agar medium. Growth rates of cotyledons cultured on hexose or sucrose media were used to inform choice of sugar concentrations. The same proportion of adaxial epidermal Cells of excised cotyledons were induced to form wall ingrowths independent of sugar species and concentration supplied. In all cases, induction of wall ingrowths coincided with a marked increase in the intraCellular sucrose-to-hexose ratio. In contrast, further progression of wall ingrowth deposition was correlated positively with intraCellular sucrose concentrations that varied depending upon external sugar species and supply. Sucrose symporter induction and subsequent maintenance behaved identically to wall ingrowth formation in response to an external supply of hexoses or sucrose. However, in contrast to wall ingrowth formation, induction of sucrose symporter activity was delayed. We discuss the possibility of intraCellular sugars functioning both as signals and substrates that induce and control subsequent development of Transfer Cells.
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Transfer Cells: Cells specialized for a special purpose.
Annual review of plant biology, 2003Co-Authors: Christina E. Offler, David W Mccurdy, John W. Patrick, Mark J TalbotAbstract:Transfer Cells are plant Cells with secondary wall ingrowths. These Cells are ubiquitous, occurring in all plant taxonomic groups and in algae and fungi. Transfer Cells form from differentiated Cells across developmental windows and in response to stress. They are considered to play a central role in nutrient distribution by facilitating high rates of transport at bottlenecks for apo-/symplasmic solute exchange. These properties are conferred by their unique structural features—an invaginated secondary wall ensheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Recent development of Transfer Cell experimental systems, combined with technologies to image the three-dimensional structure of wall ingrowths, is allowing identification of inductive and regulatory signals, discovery of sequential processes involved in their differentiation, and a search for Transfer Cell identity genes. A model of key events in differentiation of a Transfer Cell is presented to highlight a...
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Functional Transfer Cells differentiate in cultured cotyledons ofVicia faba L. seeds
Protoplasma, 2000Co-Authors: S. J. Farley, John W. Patrick, Christina E. OfflerAbstract:Transfer-Cell-like wall ingrowth deposition is induced in adaxial epidermal Cells ofVicia faba L. cotyledons grown in vitro in the presence of high hexose concentrations. We have further characterised this putative Transfer Cell induction system by examining initiation of secondary-wall ingrowth deposition and expression of sucrose transport-related genes. Wall ingrowth deposition, as wall thickening and scattered papillate ingrowths, was visualised on the outer periclinal walls of adaxial epidermal Cells of cotyledons after 1 day in culture. Over the next 2 days, wall deposition increased significantly to form a distinct band of discrete and coalescing ingrowths. Thereafter, further wall deposition was arrested. Densities of Golgi, endoplasmic reticulum, and mitochondria increased concurrently with wall ingrowth deposition. Transcripts of a H+/sucrose symporter (SUT) and a sucrose-binding protein (SBP) were detected by in situ hybridisation in differentiating Transfer Cells. Antibodies raised against an H+-ATPase immunolocalised evenly around the perimeter of the adaxial epidermal Cells in day 1 cotyledons. Thereafter, labelling became increasingly localised to the developing wall ingrowth regions. In contrast, SBP antibodies immunolocalised exclusively to wall ingrowth regions. However, SBP exhibited a transient pattern of expression, being detected only in 2-day-cultured cotyledons. A proton gradient, sufficient to facilitate sulphorhodamine G accumulation, was established by adaxial epidermal Cells after 1 day in culture. [14C]sucrose uptake by cotyledons became sensitive to an inhibitor of carrier-mediated transport of sucrose,para-chloromercuribenzene sulfonic acid after 2 days. The initial 37% inhibition of sucrose transport by this compound declined to 5% for cotyledons cultured for 3 days. Collectively, these results suggest that differentiation of the key functional characteristics of Transfer Cells can be induced in vitro, providing an exciting tool for further exploration of Transfer Cell development.
Elisa Gómez - One of the best experts on this subject based on the ideXlab platform.
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Transcriptional activation of the maize endosperm Transfer Cell-specific gene BETL1 by ZmMRP-1 is enhanced by two C_2H_2 zinc finger-containing proteins
Planta, 2009Co-Authors: Joaquín Royo, Elisa Gómez, Cristina Barrero, Luis Miguel Muñiz, Yolanda Sanz, Gregorio HuerosAbstract:ZmMRP-1 is a single MYB-domain transcription factor specifically expressed in the Transfer Cell layer of the maize endosperm, where it directly regulates the expression of a number of Transfer Cell specific genes and very likely contributes to the regulation of the Transfer Cell differentiation process. It is still a matter of debate, however, how this type of transcription factors interact with the promoter sequences they regulate. In this work we have investigated the existence of proteins interacting with ZmMRP-1 in the Transfer Cell nuclei. In a yeast double-hybrid screen we identified two related maize proteins, ZmMRPI-1 and ZmMRPI-2 belonging to the C_2H_2 zinc finger protein family, which interact with ZmMRP-1 and modulate its activity on Transfer Cell specific promoters. Two ZmMRPI orthologous genes were also identified in the rice and Arabidopsis genomes. The expression pattern in maize and Arabidopsis suggest a role for these proteins in gene regulation at the exchange surfaces where ZmMRP-1 is expressed providing the first indication of their function. We show that this previously uncharacterized family of proteins encodes nuclear proteins that interact with MYB-related transcription factors through their C-terminal conserved domain.
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the maize transcription factor myb related protein 1 is a key regulator of the differentiation of Transfer Cells
The Plant Cell, 2009Co-Authors: Elisa Gómez, Joaquín Royo, Luis M. Muñiz, Cristina Barrero, Wyatt Paul, Pascual Perez, Olivier Sellam, Denise Gerentes, Maribel Lopez, Gregorio HuerosAbstract:Transfer Cells are highly modified plant Cells specialized in the transport of solutes. They differentiate at many plant exchange surfaces, including phloem loading and unloading zones such as those present in the sink organs and seeds. In maize (Zea mays) seeds, Transfer Cells are located at the base of the endosperm. It is currently unknown how apical-basal polarity is established or why the peripheral Cells at the base of the endosperm differentiate into Transfer instead of aleurone Cells. Here, we show that in epidermal Cells committed to develop into aleurone Cells, the ectopic expression of the Transfer Cell-specific transcriptional activator Myb-Related Protein-1 (MRP-1) is sufficient to temporarily transform them into Transfer Cells. These transformed Cells acquire distinct Transfer Cell features, such as Cell wall ingrowths and an elongated shape. In addition, they express a number of MRP-1 target genes presumably involved in defense. We also show that the expression of MRP-1 is needed to maintain the Transfer Cell phenotype. Later in development, an observed reduction in the ectopic expression of MRP-1 was followed by the reversion of the transformed Cells, which then acquire aleurone Cell features.
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Molecular dissection of the interaction between the transcriptional activator ZmMRP-1 and the promoter of BETL-1
Plant Molecular Biology, 2006Co-Authors: Cristina Barrero, Elisa Gómez, Gregorio Hueros, Luis M. Muñiz, Joaquín RoyoAbstract:The interaction between the Transfer Cell specific transcriptional activator ZmMRP-1 and the promoter of the Transfer Cell specific gene BETL-1 constitutes an exceptionally robust system. Reporter constructs containing the BETL-1 promoter are virtually silent in a variety of Cell types, from maize leaves to yeast. The introduction of ZmMRP-1 in co-transformation assays leads to the transactivation of the reporter construct by up to two orders of magnitude. In this work we have investigated the molecular basis of this interaction. We found that the BETL-1 promoter includes four potential targets for ZmMRP-1 binding, consisting of a 12 bp motif containing two repeats. Co-transformation assays and electrophoretic mobility shift experiments identified the sequence TATCTCTATCTC as the preferred one for the interaction with the transcription factor. Identification of similar sequences in other Transfer Cell specific promoters lead us to propose as a Transfer Cell box a sequence related to those identified in the BETL-1 promoter, positioned 50–100 bp upstream the TATA box.
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The maize Transfer Cell-specific type-A response regulator ZmTCRR-1 appears to be involved in interCellular signalling.
The Plant journal : for cell and molecular biology, 2006Co-Authors: Luis M. Muñiz, Elisa Gómez, Joaquín Royo, Cristina Barrero, Diego Bergareche, Gregorio HuerosAbstract:Response regulators are signal-transduction molecules present in bacteria, yeast and plants, acting as relays for environmental challenges. This paper reports the characterization of a Zea mays gene, ZmTCRR-1, that codes for a member of the type-A response regulator class of proteins. The gene was found to be expressed exclusively in the endosperm Transfer-Cell layer 8-14 days after pollination, when Transfer-Cell differentiation is most active. The promoter of ZmTCRR-1 was strongly transactivated in heterologous systems by the Transfer Cell-specific transcription factor ZmMRP-1. The ZmTCRR-1 protein was detected not only in the Transfer-Cell layer, but also in the conductive tissue deep inside the endosperm, where there is no transcription of the gene. This suggests that two-component systems might be involved in interCellular signal transmission, in contrast to the generally held belief that these systems are involved only in Cell-autonomous pathways.
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Establishment of Cereal Endosperm Expression Domains Identification and Properties of a Maize Transfer Cell–Specific Transcription Factor, ZmMRP-1
The Plant cell, 2002Co-Authors: Elisa Gómez, Joaquín Royo, Yan Guo, Richard D. Thompson, Gregorio HuerosAbstract:In maize, Cells at the base of the endosperm are transformed into Transfer Cells that facilitate nutrient uptake by the developing seed. ZmMRP-1 is the first Transfer Cell-specific transcriptional activator to be identified. The protein it encodes contains nuclear localization signals and a MYB-related DNA binding domain. A single gene copy is present in maize, mapping to a locus on chromosome 8. ZmMRP-1 is first expressed soon after fertilization, when the endosperm is still a multinuclear coenocyte. The transcript accumulates in the basal nucleocytoplasmic domain that gives rise to Transfer Cells after Cellularization. The transcript can be detected throughout Transfer Cell development, but it is not found in mature Cells. ZmMRP-1 strongly transactivates the promoters of two unrelated Transfer Cell-specific genes. The properties of ZmMRP-1 are consistent with it being a determinant of Transfer Cell-specific expression. Possible roles for ZmMRP-1 in the regulation of endosperm and Transfer Cell differentiation are discussed.
Christina E. Offler - One of the best experts on this subject based on the ideXlab platform.
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A Structurally Specialized Uniform Wall Layer is Essential for Constructing Wall Ingrowth Papillae in Transfer Cells.
Frontiers in plant science, 2017Co-Authors: Xue Xia, Christina E. Offler, Hui-ming Zhang, John W. PatrickAbstract:Transfer Cells are characterized by wall labyrinths with either a flange or reticulate architecture. A literature survey established that reticulate wall ingrowth papillae ubiquitously arise from a modified component of their wall labyrinth, termed the uniform wall layer; a structure absent from flange Transfer Cells. This finding sparked an investigation of the deposition characteristics and role of the uniform wall layer using a Vicia faba cotyledon culture system. On Transfer of cotyledons to culture, their adaxial epidermal Cells spontaneously trans-differentiate to a reticulate architecture comparable to their abaxial epidermal Transfer Cell counterparts formed in planta. Uniform wall layer construction commenced once adaxial epidermal Cell expansion had ceased to overlay the original outer periclinal wall on its inner surface. In contrast to the dense ring-like lattice of Cellulose microfibrils in the original primary wall, the uniform wall layer was characterized by a sparsely dispersed array of linear Cellulose microfibrils. A re-modelled cortical microtubule array exerted no influence on uniform wall layer formation or on its Cellulose microfibril organization. Surprisingly, formation of the uniform wall layer was not dependent upon depositing a Cellulose scaffold. In contrast, uniform wall Cellulose microfibrils were essential precursors for constructing wall ingrowth papillae. On converging to form wall ingrowth papillae, the Cellulose microfibril diameters increased three-fold. This event correlated with up-regulated differential, and Transfer-Cell specific, expression of VfCesA3B while transcript levels of other Cellulose biosynthetic-related genes linked with primary wall construction were substantially down regulated.
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Differential transcriptional networks associated with key phases of ingrowth wall construction in trans-differentiating epidermal Transfer Cells of Vicia faba cotyledons
BMC Plant Biology, 2015Co-Authors: Hui-ming Zhang, Christina E. Offler, Simon Wheeler, Xue Xia, Ruslana Radchuk, Hans Weber, John W. PatrickAbstract:Background Transfer Cells are characterized by intricate ingrowth walls, comprising an uniform wall upon which wall ingrowths are deposited. The ingrowth wall forms a scaffold to support an amplified plasma membrane surface area enriched in membrane transporters that collectively confers Transfer Cells with an enhanced capacity for membrane transport at bottlenecks for apo-/symplasmic exchange of nutrients. However, the underlying molecular mechanisms regulating polarized construction of the ingrowth wall and membrane transporter profile are poorly understood. Results An RNAseq study of an inducible epidermal Transfer Cell system in cultured Vicia faba cotyledons identified Transfer Cell specific transcriptomes associated with uniform wall and wall ingrowth deposition. All functional groups of genes examined were expressed before and following transition to a Transfer Cell fate. What changed were the isoform profiles of expressed genes within functional groups. Genes encoding ethylene and Ca^2+ signal generation and transduction pathways were enriched during uniform wall construction. Auxin-and reactive oxygen species-related genes dominated during wall ingrowth formation and ABA genes were evenly expressed across ingrowth wall construction. Expression of genes encoding kinesins, formins and villins was consistent with reorganization of cytoskeletal components. Uniform wall and wall ingrowth specific expression of exocyst complex components and SNAREs suggested specific patterns of exocytosis while dynamin mediated endocytotic activity was consistent with establishing wall ingrowth loci. Key regulatory genes of biosynthetic pathways for sphingolipids and sterols were expressed across ingrowth wall construction. Transfer Cell specific expression of Cellulose synthases was absent. Rather xyloglucan, xylan and pectin biosynthetic genes were selectively expressed during uniform wall construction. More striking was expression of genes encoding enzymes for re-modelling/degradation of Cellulose, xyloglucans, pectins and callose. Extensins dominated the cohort of expressed wall structural proteins and particularly so across wall ingrowth development. Ion transporters were selectively expressed throughout ingrowth wall development along with organic nitrogen transporters and a large group of ABC transporters. Sugar transporters were less represented. Conclusions Pathways regulating signalling and intraCellular organization were fine tuned whilst Cell wall construction and membrane transporter profiles were altered substantially upon transiting to a Transfer Cell fate. Each phase of ingrowth wall construction was linked with unique cohorts of expressed genes.
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Role of sugars in regulating Transfer Cell development in cotyledons of developing Vicia faba seeds.
Protoplasma, 2006Co-Authors: T. Wardini, Christina E. Offler, Mark J Talbot, John W. PatrickAbstract:Transfer Cell formation in cotyledons of developing faba bean (Vicia faba L.) seeds coincides with an abrupt change in seed apoplasm composition from one dominated by hexoses to one in which sucrose is the principal sugar. On the basis of these observations, we tested the hypothesis that sugars induce and/or sustain Transfer Cell development. To avoid confounding effects of in planta developmental programs, we exploited the finding that adaxial epidermal Cells of cotyledons, which do not become Transfer Cells in planta, can be induced to form functional Transfer Cells when cotyledons are cultured on an agar medium. Growth rates of cotyledons cultured on hexose or sucrose media were used to inform choice of sugar concentrations. The same proportion of adaxial epidermal Cells of excised cotyledons were induced to form wall ingrowths independent of sugar species and concentration supplied. In all cases, induction of wall ingrowths coincided with a marked increase in the intraCellular sucrose-to-hexose ratio. In contrast, further progression of wall ingrowth deposition was correlated positively with intraCellular sucrose concentrations that varied depending upon external sugar species and supply. Sucrose symporter induction and subsequent maintenance behaved identically to wall ingrowth formation in response to an external supply of hexoses or sucrose. However, in contrast to wall ingrowth formation, induction of sucrose symporter activity was delayed. We discuss the possibility of intraCellular sugars functioning both as signals and substrates that induce and control subsequent development of Transfer Cells.
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Transfer Cells: Cells specialized for a special purpose.
Annual review of plant biology, 2003Co-Authors: Christina E. Offler, David W Mccurdy, John W. Patrick, Mark J TalbotAbstract:Transfer Cells are plant Cells with secondary wall ingrowths. These Cells are ubiquitous, occurring in all plant taxonomic groups and in algae and fungi. Transfer Cells form from differentiated Cells across developmental windows and in response to stress. They are considered to play a central role in nutrient distribution by facilitating high rates of transport at bottlenecks for apo-/symplasmic solute exchange. These properties are conferred by their unique structural features—an invaginated secondary wall ensheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Recent development of Transfer Cell experimental systems, combined with technologies to image the three-dimensional structure of wall ingrowths, is allowing identification of inductive and regulatory signals, discovery of sequential processes involved in their differentiation, and a search for Transfer Cell identity genes. A model of key events in differentiation of a Transfer Cell is presented to highlight a...
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Transfer Cell wall architecture: a contribution towards understanding localized wall deposition.
Protoplasma, 2002Co-Authors: Mark J Talbot, Christina E. Offler, David W MccurdyAbstract:A survey is presented of the architecture of secondary wall ingrowths in Transfer Cells from various taxa based on scanning electron microscopy. Wall ingrowths are a distinguishing feature of Transfer Cells and serve to amplify the plasma membrane surface area available for solute transport. Morphologically, two categories of ingrowths are recognized: reticulate and flange. Reticulate-type wall ingrowths are characterized by the deposition of small papillae that emerge from the underlying wall at discrete but apparently random loci, then branch and interconnect to form a complex labyrinth of variable morphology. In comparison, flange-type ingrowths are deposited as curvilinear ribs of wall material that remain in contact with the underlying wall along their length and become variously elaborate in different Transfer Cell types. This paper discusses the morphology of different types of wall ingrowths in relation to existing models for deposition of other secondary Cell walls.