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Daniel J. Cosgrove - One of the best experts on this subject based on the ideXlab platform.
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global cellulose biomass horizontal gene transfers and domain fusions drive microbial Expansin evolution
New Phytologist, 2020Co-Authors: William R Chase, Daniel J. Cosgrove, Olga Zhaxybayeva, Jorge Rocha, Lori R ShapiroAbstract:: Plants must rearrange the network of complex carbohydrates in their cell walls during normal growth and development. To accomplish this, all plants depend on proteins called Expansins that nonenzymatically loosen noncovalent bonding between cellulose microfibrils. Surprisingly, Expansin genes have more recently been found in some bacteria and microbial eukaryotes, where their biological functions are largely unknown. Here, we reconstruct a comprehensive phylogeny of microbial Expansin genes. We find these genes in all eukaryotic microorganisms that have structural cell wall cellulose, suggesting Expansins evolved in ancient marine microorganisms long before the evolution of land plants. We also find Expansins in an unexpectedly high diversity of bacteria and fungi that do not have cellulosic cell walls. These bacteria and fungi inhabit varied ecological contexts, mirroring the diversity of terrestrial and aquatic niches where plant and/or algal cellulosic cell walls are present. The microbial Expansin phylogeny shows evidence of multiple horizontal gene transfer events within and between bacterial and eukaryotic microbial lineages, which may in part underlie their unusually broad phylogenetic distribution. Overall, Expansins are unexpectedly widespread in bacteria and eukaryotes, and the contribution of these genes to microbial ecological interactions with plants and algae has probbaly been underappreciated.
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Expansin gene loss is a common occurrence during adaptation to an aquatic environment
Plant Journal, 2020Co-Authors: Nathan K. Hepler, Robert E. Carey, Alexa Bowman, Daniel J. CosgroveAbstract:Expansins comprise a superfamily of plant cell wall loosening proteins that can be divided into four individual families (EXPA, EXPB, EXLA and EXLB). Aside from inferred roles in a variety of plant growth and developmental traits, little is known regarding the function of specific Expansin clades, for which there are at least 16 in flowering plants (angiosperms); however, there is evidence to suggest that some Expansins have cell-specific functions, in root hair and pollen tube development, for example. Recently, two duckweed genomes have been sequenced (Spirodela polyrhiza strains 7498 and 9509), revealing significantly reduced superfamily sizes. We hypothesized that there would be a correlation between Expansin loss and morphological reductions seen among highly adapted aquatic species. In order to provide an answer to this question, we characterized the Expansin superfamilies of the greater duckweed Spirodela, the marine eelgrass Zostera marina and the bladderwort Utricularia gibba. We discovered rampant Expansin gene and clade loss among the three, including a complete absence of the EXLB family and EXPA-VII. The most convincing correlation between morphological reduction and Expansin loss was seen for Utricularia and Spirodela, which both lack root hairs and the root hair Expansin clade EXPA-X. Contrary to the pattern observed in other species, four Utricularia Expansins failed to branch within any clade, suggesting that they may be the result of neofunctionalization. Last, an Expansin clade previously discovered only in eudicots was identified in Spirodela, allowing us to conclude that the last common ancestor of monocots and eudicots contained a minimum of 17 Expansins.
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Bacterial Expansins and related proteins from the world of microbes
Applied Microbiology and Biotechnology, 2015Co-Authors: Nikolaos Georgelis, Nikolas Nikolaidis, Daniel J. CosgroveAbstract:The discovery of microbial Expansins emerged from studies of the mechanism of plant cell growth and the molecular basis of plant cell wall extensibility. Expansins are wall-loosening proteins that are universal in the plant kingdom and are also found in a small set of phylogenetically diverse bacteria, fungi, and other organisms, most of which colonize plant surfaces. They loosen plant cell walls without detectable lytic activity. Bacterial Expansins have attracted considerable attention recently for their potential use in cellulosic biomass conversion for biofuel production, as a means to disaggregate cellulosic structures by nonlytic means (“amorphogenesis”). Evolutionary analysis indicates that microbial Expansins originated by multiple horizontal gene transfers from plants. Crystallographic analysis of BsEXLX1, the Expansin from Bacillus subtilis , shows that microbial Expansins consist of two tightly packed domains: the N-terminal domain D1 has a double-ψ β-barrel fold similar to glycosyl hydrolase family-45 enzymes but lacks catalytic residues usually required for hydrolysis; the C-terminal domain D2 has a unique β-sandwich fold with three co-linear aromatic residues that bind β-1,4-glucans by hydrophobic interactions. Genetic deletion of Expansin in Bacillus and Clavibacter cripples their ability to colonize plant tissues. We assess reports that Expansin addition enhances cellulose breakdown by cellulase and compare Expansins with distantly related proteins named swollenin, cerato-platanin, and loosenin. We end in a speculative vein about the biological roles of microbial Expansins and their potential applications. Advances in this field will be aided by a deeper understanding of how these proteins modify cellulosic structures.
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evolutionary divergence of β Expansin structure and function in grasses parallels emergence of distinctive primary cell wall traits
Plant Journal, 2015Co-Authors: Javier Sampedro, Mara Guttman, Daniel J. CosgroveAbstract:Summary Expansins are wall-loosening proteins that promote the extension of primary cell walls without the hydrolysis of major structural components. Previously, proteins from the EXPA (α–Expansin) family were found to loosen eudicot cell walls but to be less effective on grass cell walls, whereas the reverse pattern was found for EXPB (β–Expansin) proteins obtained from grass pollen. To understand the evolutionary and structural bases for the selectivity of EXPB action, we assessed the extension (creep) response of cell walls from diverse monocot families to EXPA and EXPB treatments. Cell walls from Cyperaceae and Juncaceae (families closely related to grasses) displayed a typical grass response (‘β–response’). Walls from more distant monocots, including some species that share with grasses high levels of arabinoxylan, responded preferentially to α–Expansins (‘α–response’), behaving in this regard like eudicots. An Expansin with selective activity for grass cell walls was detected in Cyperaceae pollen, coinciding with the expression of genes from the divergent EXPB–I branch that includes grass pollen β–Expansins. The evolutionary origin of this branch was located within Poales on the basis of phylogenetic analyses and its association with the ‘sigma’ whole-genome duplication. Accelerated evolution in this branch has remodeled the protein surface in contact with the substrate, potentially for binding highly substituted arabinoxylan. We propose that the evolution of the divergent EXPB–I group made a fundamental change in the target and mechanism of wall loosening in the grass lineage possible, involving a new structural role for xylans and the Expansins that target them.
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plant Expansins in bacteria and fungi evolution by horizontal gene transfer and independent domain fusion
Molecular Biology and Evolution, 2014Co-Authors: Nikolas Nikolaidis, Nicole Doran, Daniel J. CosgroveAbstract:Horizontal gene transfer (HGT) has been described as a common mechanism of transferring genetic material between prokaryotes, whereas genetic transfers from eukaryotes to prokaryotes have been rarely documented. Here we report a rare case of HGT in which plant Expansin genes that code for plant cell-wall loosening proteins were transferred from plants to bacteria, fungi, and amoebozoa. In several cases, the species in which the Expansin gene was found is either in intimate association with plants or is a known plant pathogen. Our analyses suggest that at least two independent genetic transfers occurred from plants to bacteria and fungi. These events were followed by multiple HGT events within bacteria and fungi. We have also observed that in bacteria Expansin genes have been independently fused to DNA fragments that code for an endoglucanase domain or for a carbohydrate binding module, pointing to functional convergence at the molecular level. Furthermore, the functional similarities between microbial Expansins and their plant xenologs suggest that these proteins mediate microbial-plant interactions by altering the plant cell wall and therefore may provide adaptive advantages to these species. The evolution of these nonplant Expansins represents a unique case in which bacteria and fungi have found innovative and adaptive ways to interact with and infect plants by acquiring genes from their host. This evolutionary paradigm suggests that despite their low frequency such HGT events may have significantly contributed to the evolution of prokaryotic and eukaryotic species.
Simon J Mcqueenmason - One of the best experts on this subject based on the ideXlab platform.
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ph and Expansin action on single suspension cultured tomato lycopersicon esculentum cells
Journal of Plant Research, 2008Co-Authors: C X Wang, Simon J Mcqueenmason, L Wang, Jeremy Pritchard, C R ThomasAbstract:The aim of this study was to measure key material properties of the cell walls of single suspension-cultured plant cells and relate these to cell-wall biochemistry. To this end, micromanipulation was used to compress single tomato cells between two flat surfaces until they ruptured, and force-deformation data were obtained. In addition to measuring the bursting force, we also determined the elastic (Young’s) modulus of the cell walls by matching low strain (≤20% deformation) experimental data with a cell compression model, assuming linear elastic cell walls. The walls were most elastic at pH 4.5, the pH optimum for Expansin activity, with an elastic modulus of 2.0 ± 0.1 GPa. Following the addition of exogenous Expansins, cell walls became more elastic at all pH values. Western blot analysis of proteins from walls of cultured cells revealed the presence of Expansin epitopes, suggesting that the inherent pH dependence of elasticity and other compression phenomena is related to the presence of endogenous Expansin proteins and their wall-loosening ability. Although strict application of the linear-elastic model could not be applied to large deformations—for example, up to cell bursting—because of irreversible behaviour, the deviation of the data from the model was generally small enough to allow estimation of the strain in the cell wall at failure. This strain was greater at pH 4.5 and when Expansins were added to the suspension. The changes in elasticity are consistent with suggestions about the mode of Expansin action. The estimated strains at failure are compatible with data on the failure of Acetobacter-derived cellulose–xyloglucan composites and proposed mechanisms of such failure. Through the measurement of cell-wall material properties using micromanipulation, it may be possible to understand more fully how cell-wall composition, structure and biochemistry lead to cell mechanical behaviour.
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ectopic expression of a wood abundant Expansin pttexpa1 promotes cell expansion in primary and secondary tissues in aspen
Plant Biotechnology Journal, 2007Co-Authors: Madoka Graymitsumune, Simon J Mcqueenmason, Tuula T Teeri, Kristina Blomquist, Bjoern W Sundberg, Ewa J MellerowiczAbstract:Expansins are primary agents inducing cell wall extension, and are therefore obvious targets in biotechnological applications aimed at the modification of cell size in plants. In trees, increased fibre length is a goal of both breeding and genetic engineering programmes. We used an alpha-Expansin PttEXPA1 that is highly abundant in the wood-forming tissues of hybrid aspen (Populus tremula L. x P. tremuloides Michx.) to evaluate its role in fibre elongation and wood cell development. PttEXPA1 belongs to Subfamily A of alpha-Expansins that have conserved motifs at the N- and C-termini of the mature protein. When PttEXPA1 was over-expressed in aspen, an extract of the cell wall-bound proteins of the transgenic plants exhibited an increased Expansin activity on cellulose-xyloglucan composites in vitro, indicating that PttEXPA1 is an active Expansin. The transgenic lines exhibited increased stem internode elongation and leaf expansion, and larger cell sizes in the leaf epidermis, indicating that PttEXPA1 protein is capable of increasing the growth of these organs by enhancing cell wall expansion in planta. Wood cell development was also modified in the transgenic lines, but the effects were different for vessel elements and fibres, the two main cell types of aspen wood. PttEXPA1 stimulated fibre, but not vessel element, diameter growth, and marginally increased vessel element length, but did not affect fibre length. The observed differences in responsiveness to Expansin of these cell types are discussed in the light of differences in their growth strategies and cell wall composition.
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changes in Expansin activity and gene expression during ethylene promoted leaflet abscission in sambucus nigra
Journal of Experimental Botany, 2005Co-Authors: Eric John Belfield, Benedetto Ruperti, Jeremy A Roberts, Simon J McqueenmasonAbstract:During ethylene-promoted leaflet abscission in Sambucus nigra a 7-fold increase in Expansin activity was detected specifically in tissues undergoing cell separation, whilst only low levels of activity were seen in adjacent non-abscising tissues. An RT-PCR strategy was used to amplify Expansin fragments from a cDNA library generated from mRNA extracted from ethylenetreated leaflet abscission-zone tissue. Two different full-length Expansin-encoding cDNAs were isolated with sizes of 1190 bp and 1169 bp and named SniExp2 and SniExp4, respectively. The deduced protein sequences of SniExp2 and SniExp4 exhibited 67% homology and comprised 256 and 249 amino acids, respectively. Both putative proteins contained signal sequences at their N terminal ends, suggesting that they were likely to encode secreted or transmembrane proteins. Northern analyses with probes specific for each gene revealed that transcripts for both of these cDNAs accumulated specifically in abscission zone tissues in response to ethylene treatment, with no expression being apparent in either freshly excised material or non-separating tissues. These data support a role for Expansins in ethylene-stimulated abscission and provide evidence that specific family members contribute to the cell separation process that takes place during organ shedding.
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Expansins abundant in secondary xylem belong to subgroup a of the α Expansin gene family
Plant Physiology, 2004Co-Authors: Madoka Graymitsumune, Simon J Mcqueenmason, Ewa J Mellerowicz, Hisashi Abe, Jarmo Schrader, Anders Winzell, Fredrik Sterky, Kristina Blomqvist, Tuula T Teeri, Bjorn SundbergAbstract:Differentiation of xylem cells in dicotyledonous plants involves expansion of the radial primary cell walls and intrusive tip growth of cambial derivative cells prior to the deposition of a thick secondary wall essential for xylem function. Expansins are cell wall-residing proteins that have an ability to plasticize the cellulose-hemicellulose network of primary walls. We found Expansin activity in proteins extracted from the cambial region of mature stems in a model tree species hybrid aspen (Populus tremula x Populus tremuloides Michx). We identified three alpha-Expansin genes (PttEXP1, PttEXP2, and PttEXP8) and one beta-Expansin gene (PttEXPB1) in a cambial region expressed sequence tag library, among which PttEXP1 was most abundantly represented. Northern-blot analyses in aspen vegetative organs and tissues showed that PttEXP1 was specifically expressed in mature stems exhibiting secondary growth, where it was present in the cambium and in the radial expansion zone. By contrast, PttEXP2 was mostly expressed in developing leaves. In situ reverse transcription-PCR provided evidence for accumulation of mRNA of PttEXP1 along with ribosomal rRNA at the tips of intrusively growing xylem fibers, suggesting that PttEXP1 protein has a role in intrusive tip growth. An examination of tension wood and leaf cDNA libraries identified another Expansin, PttEXP5, very similar to PttEXP1, as the major Expansin in developing tension wood, while PttEXP3 was the major Expansin expressed in developing leaves. Comparative analysis of Expansins expressed in woody stems in aspen, Arabidopsis, and pine showed that the most abundantly expressed Expansins share sequence similarities, belonging to the subfamily A of alpha-Expansins and having two conserved motifs at the beginning and end of the mature protein, RIPVG and KNFRV, respectively. This conservation suggests that these genes may share a specialized, not yet identified function.
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local expression of Expansin induces the entire process of leaf development and modifies leaf shape
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Stephane Pien, Simon J Mcqueenmason, Joanna Wyrzykowska, Cheryl C Smart, Andrew J FlemingAbstract:Expansins are a family of extracellular proteins proposed to play a key role in wall stress relaxation and, thus, in cell and tissue growth. To test the possible function of Expansins in morphogenesis, we have developed a technique that allows transient local microinduction of gene expression in transgenic plants. We have used this system to manipulate Expansin gene expression in various tissues. Our results indicate that local Expansin expression within the meristem induces a developmental program that recapitulates the entire process of leaf formation. Moreover, local transient induction of Expansin expression on the flank of developing primordia leads to the induction of ectopic lamina tissue and thus modulation of leaf shape. These data describe an approach for the local manipulation of gene expression and indicate a role for Expansin in the control of both leaf initiation and shape. These results are consistent with the action of cell division-independent mechanisms in plant morphogenesis.
Jocelyn K C Rose - One of the best experts on this subject based on the ideXlab platform.
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Expansin protein levels decline with the development of mealiness in peaches
Postharvest Biology and Technology, 2003Co-Authors: David Obenland, Carlos H Crisosto, Jocelyn K C RoseAbstract:Expansin mRNA and protein expression in peaches was examined to investigate the possibility that Expansins may be involved in the development of mealy flesh texture. Immunoblot analysis, using an Expansin antibody, detected a 27kDa protein corresponding to the predicted molecular mass of Expansins in the later stages of ripening but not in fullsize green fruit and indicated that Expansin is associated with the progression of ripening in peaches. Peach cultivars ‘O’Henry’ and ‘Summer Lady’ were stored at 5 8C to induce the development of mealiness and individual fruit samples collected periodically to measure mealiness (free water) and provide samples for Expansin quantification. Initially, stored fruit were juicy (50/60% free water), but as storage progressed they became visibly mealy at free water percentages of 30% for ‘O’Henry’ and 46% for ‘Summer Lady’. In both cultivars Expansin protein abundance decreased as the fruit became mealy. Development of mealiness within individual fruit was often not uniform and lead to the existence of distinct juicy and mealy regions. Immunoblot analysis indicated that mealy regions contained substantially less Expansin than juicy regions. Analysis of Expansin mRNA abundance using a ripening-related Expansin cDNA probe from peach indicated that Expansin mRNA expression was also markedly reduced in mealy tissues. The relationship observed in this study between Expansin expression and mealiness suggests a possible role for Expansin in the development of the disorder. Published by Elsevier Science B.V.
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differential expression of seven α Expansin genes during growth and ripening of pear fruit
Physiologia Plantarum, 2003Co-Authors: Kyoko Hiwasa, Jocelyn K C Rose, Ryohei Nakano, Akitsugu Inaba, Yasutaka KuboAbstract:Seven cDNAs, designated PcExp1 to PcExp7, encoding Expansin homologues, were isolated from mature pear fruit and their expression profiles were investigated in ripening fruit and other tissues, and in response to ethylene. Accumulation of PcExp2, -3, -5 and -6 mRNA increased markedly with fruit softening and then declined at the over-ripe stage. Treatment of fruit at an early ripening stage with 1-methylcyclopropene (MCP), an inhibitor of ethylene action, suppressed ethylene biosynthesis, fruit softening and the accumulation of the Expansin mRNAs. Conversely, propylene treatment at the preclimacteric stage induced accumulation of the same four Expansin genes, as well as ethylene production and fruit softening. The expression patterns correlated with alteration in the rate and extent of fruit softening. The abundance of PcExp1 mRNA increased at the late expanding phase of fruit development and further increased during ripening, whereas PcExp4 mRNA levels were constant throughout fruit growth and ripening. The MCP and propylene treatments had little effect on PcExp1 and PcExp4 expression. PcExp7 was expressed in young but not mature fruit. PcExp4 and PcExp6 mRNA was also detected in flowers. The accumulation of PcExp4, -5, -6 and -7 mRNA was more abundant in young growing tissues, but not in fully expanded tissues, suggesting roles for these genes in cell expansion. These results demonstrate that characteristically, multiple Expansin genes show differential expression and hormonal regulation during pear fruit development and at least six Expansins show overlapping expression during ripening.
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detection of Expansin proteins and activity during tomato fruit ontogeny
Plant Physiology, 2000Co-Authors: Jocelyn K C Rose, Daniel J. Cosgrove, Peter Albersheim, Alan G Darvill, Alan B BennettAbstract:Expansins are plant proteins that have the capacity to induce extension in isolated cell walls and are thought to mediate pH-dependent cell expansion. J.K.C. Rose, H.H. Lee, and A.B. Bennett ([1997] Proc Natl Acad Sci USA 94: 5955–5960) reported the identification of an Expansin gene ( LeExp1 ) that is specifically expressed in ripening tomato ( Lycopersicon esculentum ) fruit where cell wall disassembly, but not cell expansion, is prominent. Expansin expression during fruit ontogeny was examined using antibodies raised to recombinant LeExp1 or a cell elongation-related Expansin from cucumber (CsExp1). The LeExp1 antiserum detected Expansins in extracts from ripe, but not preripe tomato fruit, in agreement with the pattern of LeExp1 mRNA accumulation. In contrast, antibodies to CsExp1 cross-reacted with Expansins in early fruit development and the onset of ripening, but not at a later ripening stage. These data suggest that ripening-related and expansion-related Expansin proteins have distinct antigenic epitopes despite overall high sequence identity. Expansin proteins were detected in a range of fruit species and showed considerable variation in abundance; however, appreciable levels of Expansin were not present in fruit of the rin or Nr tomato mutants that exhibit delayed and reduced softening. LeExp1 protein accumulation was ethylene-regulated and matched the previously described expression of mRNA, suggesting that expression is not regulated at the level of translation. We report the first detection of Expansin activity in several stages of fruit development and while characteristic creep activity was detected in young and developing tomato fruit and in ripe pear, avocado, and pepper, creep activity in ripe tomato showed qualitative differences, suggesting both hydrolytic and Expansin activities.
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limited correlation between Expansin gene expression and elongation growth rate
Plant Physiology, 2000Co-Authors: Doina Caderas, Jocelyn K C Rose, Simon J Mcqueenmason, Therese Mandel, Matthias Muster, Hannes Vogler, Cris KuhlemeierAbstract:The aim of this work was to study the role of the cell wall protein Expansin in elongation growth. Expansins increase cell wall extensibility in vitro and are thought to be involved in cell elongation. Here, we studied the regulation of two tomato (Lycopersicon esculentum cv Moneymaker) Expansin genes, LeExp2 and LeExp18, in rapidly expanding tissues. LeExp2 was strongly expressed in the elongation zone of hypocotyls and in the faster growing stem part during gravitropic stimulation. LeExp18 expression did not correlate with elongation growth. Exogenous application of hormones showed a substantial auxin-stimulation of LeExp2 mRNA in etiolated hypocotyls and a weaker auxin-stimulation of LeExp18 mRNA in stem tissue. Analysis of transcript accumulation revealed higher levels of LeExp2 and LeExp18 in light-treated, slow-growing tissue than in dark-treated, rapidly elongating tissue. Expansin protein levels and cell wall extension activities were similar in light- and dark-grown hypocotyl extracts. The results show a strong correlation between Expansin gene expression and growth rate, but this correlation is not absolute. We conclude that elongation growth is likely to be controlled by Expansin acting in concert with other factors that may limit growth under some physiological conditions.
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expression of a divergent Expansin gene is fruit specific and ripening regulated
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Jocelyn K C Rose, Howard H Lee, Alan B BennettAbstract:Expansins are proteins that induce extension in isolated plant cell walls in vitro and have been proposed to disrupt noncovalent interactions between hemicellulose and cellulose microfibrils. Because the plant primary cell wall acts as a constraint to cell enlargement, this process may be integral to plant cell expansion, and studies of Expansins have focused on their role in growth. We report the identification of an Expansin (LeExp1) from tomato that exhibits high levels of mRNA abundance and is specifically expressed in ripening fruit, a developmental period when growth has ceased but when selective disassembly of cell wall components is pronounced. cDNAs closely related to LeExp1 were also identified in ripening melons and strawberries, suggesting that they are a common feature of fruit undergoing rapid softening. Furthermore, the sequence of LeExp1 and its homologs from other ripening fruit define a subclass of Expansin genes. Expression of LeExp1 is regulated by ethylene, a hormone known to coordinate and induce ripening in many species. LeExp1 is differentially expressed in the ripening-impaired tomato mutants Nr, rin, and nor, and mRNA abundance appears to be influenced directly by ethylene and by a developmentally modulated transduction pathway. The identification of a ripening-regulated Expansin gene in tomato and other fruit suggests that, in addition to their role in facilitating the expansion of plant cells, Expansins may also contribute to cell wall disassembly in nongrowing tissues, possibly by enhancing the accessibility of noncovalently bound polymers to endogenous enzymic action.
Andrew J Fleming - One of the best experts on this subject based on the ideXlab platform.
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variable Expansin expression in arabidopsis leads to different growth responses
Journal of Plant Physiology, 2014Co-Authors: Jennifer Sloan, Hoe Han Goh, Robert Malinowski, Andrew J FlemingAbstract:Expansins have long been implicated in the control of cell wall extensibility. However, despite ample evidence supporting a role for these proteins in the endogenous mechanism of plant growth, there are also examples in the literature where the outcome of altered Expansin gene expression is difficult to reconcile with a simplistic causal linkage to growth promotion. To investigate this problem, we report on the analysis of transgenic Arabidopsis plants in which a heterologous cucumber Expansin can be inducibly overexpressed. Our results indicate that the effects of Expansin expression on growth depend on the degree of induction of Expansin expression and the developmental pattern of organ growth. They support the role of Expansin in directional cell expansion. They are also consistent with the idea that excess Expansin might itself impede normal activities of cell wall modifications, culminating in both growth promotion and repression depending on the degree of expression.
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inducible repression of multiple Expansin genes leads to growth suppression during leaf development
Plant Physiology, 2012Co-Authors: Hoe Han Goh, Jennifer Sloan, Carmen Dorcafornell, Andrew J FlemingAbstract:Expansins are cell wall proteins implicated in the control of plant growth via loosening of the extracellular matrix. They are encoded by a large gene family, and data linked to loss of single gene function to support a role of Expansins in leaf growth remain limited. Here, we provide a quantitative growth analysis of transgenics containing an inducible artificial microRNA construct designed to down-regulate the expression of a number of Expansin genes that an expression analysis indicated are expressed during the development of Arabidopsis (Arabidopsis thaliana) leaf 6. The results support the hypothesis that Expansins are required for leaf growth and show that decreased Expansin gene expression leads to a more marked repression of growth during the later stage of leaf development. In addition, a histological analysis of leaves in which Expansin gene expression was suppressed indicates that, despite smaller leaves, mean cell size was increased. These data provide functional evidence for a role of Expansins in leaf growth, indicate the importance of tissue/organ developmental context for the outcome of altered Expansin gene expression, and highlight the separation of the outcome of Expansin gene expression at the cellular and organ levels.
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local expression of Expansin induces the entire process of leaf development and modifies leaf shape
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Stephane Pien, Simon J Mcqueenmason, Joanna Wyrzykowska, Cheryl C Smart, Andrew J FlemingAbstract:Expansins are a family of extracellular proteins proposed to play a key role in wall stress relaxation and, thus, in cell and tissue growth. To test the possible function of Expansins in morphogenesis, we have developed a technique that allows transient local microinduction of gene expression in transgenic plants. We have used this system to manipulate Expansin gene expression in various tissues. Our results indicate that local Expansin expression within the meristem induces a developmental program that recapitulates the entire process of leaf formation. Moreover, local transient induction of Expansin expression on the flank of developing primordia leads to the induction of ectopic lamina tissue and thus modulation of leaf shape. These data describe an approach for the local manipulation of gene expression and indicate a role for Expansin in the control of both leaf initiation and shape. These results are consistent with the action of cell division-independent mechanisms in plant morphogenesis.
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differential expression of α and β Expansin genes in the elongating leaf of festuca pratensis
Plant Molecular Biology, 2001Co-Authors: Beat Reidy, Simon J Mcqueenmason, J Nosberger, Andrew J FlemingAbstract:Grasses contain a number of genes encoding both α- and β-Expansins. These cell wall proteins are predicted to play a role in cell wall modifications, particularly during tissue elongation. We report here on the characterisation of five α- and three vegetative β-Expansins expressed in the leaf elongation zone (LEZ) of the forage grass, Festuca pratensis Huds. The expression of the predominant α-Expansin (FpExp2) was localised to the vascular tissue, as was the β-Expansin FpExpB3. Expression of another β-Expansin (FpExpB2) was not localised to vascular tissue but was highly expressed in roots and initiating tillers. This is the first description of vegetative β-Expansin gene expression at the organ and tissue level and also the first evidence of differential expression between members of this gene family. In addition, an analysis of both α- and β-Expansin expression along the LEZ revealed no correlation with growth rate distribution, whereas we were able to identify a novel xyloglucan endotransglycosylase (FpXET1) whose expression profile closely mimicked leaf growth rate. These data suggest that α- and β-Expansin activities in the grass leaf are associated with tissue differentiation, that Expansins involved in leaf growth may represent more minor components of the spectrum of Expansin genes expressed in this tissue, and that XETs may be useful markers for the analysis of grass leaf growth.
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analysis of Expansin induced morphogenesis on the apical meristem of tomato
Planta, 1999Co-Authors: Andrew J Fleming, Simon J Mcqueenmason, Doina Caderas, Ernst Wehrli, Cris KuhlemeierAbstract:Our previous work has shown that localised activity of the cell-wall-loosening protein Expansin is sufficient to induce primordia on the apical meristem of tomato, consistent with the hypothesis that tissue expansion plays a key role in leaf initiation. In this paper we describe the earliest morphogenic events visible on the surface of the apical meristem of tomato (Lycopersicon esculentum Mill.) following treatment with Expansin and report on the spectrum of final structures formed. Our observations are consistent with a proposed primary function of Expansin effecting morphogenesis via altered biophysical stress patterns in the meristem. The primordia induced by Expansin do not complete the full program of leaf development. We present data indicating that one reason for this might be the inability of exogenous Expansin to mimic the endogenous pattern of Expansin activity in the meristem. These data provide the first detailed analysis at the cellular level of Expansin action on living tissue, the first description of the spectrum of structures induced by Expansin on the apical meristem, and give an insight into a potentially fundamental mechanism in plant development.
Yingzhen Kong - One of the best experts on this subject based on the ideXlab platform.
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genome wide identification of the Expansin gene family in tobacco nicotiana tabacum
Molecular Genetics and Genomics, 2016Co-Authors: Anming Ding, Prince Marowa, Yingzhen KongAbstract:Expansins are pH-dependent cell wall loosening proteins which form a large family in plants. They have been shown to be involved in various developmental processes and been implicated in enabling plants' ability to absorb nutrients from the soil as well as conferring biotic and abiotic stress resistances. It is therefore clear that they can be potential targets in genetic engineering for crop improvement. Tobacco (Nicotiana tabacum) is a major crop species as well as a model organism. Considering that only a few tobacco Expansins have been studied, a genome-wide analysis of the tobacco Expansin gene family is necessary. In this study, we identified 52 Expansins in tobacco, which were classified into four subfamilies: 36 NtEXPAs, 6 NtEXPBs, 3 NtEXLAs and 7 NtEXLBs. Compared to other species, the NtEXLB subfamily size was relatively larger. Phylogenetic analysis showed that the 52 tobacco Expansins were divided into 13 subgroups. Gene structure analysis revealed that genes within subfamilies/subgroups exhibited similar characteristics such as gene structure and protein motif arrangement. Whole-genome duplication and tandem duplication events may have played important roles in the expanding of tobacco Expansins. Cis-Acting element analysis revealed that each Expansin gene was regulated or several Expansin genes were co-regulated by both internal and environmental factors. 35 of these genes were identified as being expressed according to a microarray analysis. In contrast to most NtEXPAs which had higher expression levels in young organs, NtEXLAs and NtEXLBs were preferentially expressed in mature or senescent tissues, suggesting that they might play different roles in different organs or at different developmental stages. As the first step towards genome-wide analysis of the tobacco Expansin gene family, our work provides solid background information related to structure, evolution and expression as well as regulatory cis-acting elements of the tobacco Expansins. This information will provide a strong foundation for cloning and functional exploration of Expansin genes in tobacco.
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Expansins roles in plant growth and potential applications in crop improvement
Plant Cell Reports, 2016Co-Authors: Prince Marowa, Anming Ding, Yingzhen KongAbstract:Key message Results from various Expansin related studies have demonstrated that Expansins present an opportunity to improve various crops in many different aspects ranging from yield and fruit ripening to improved stress tolerance.
