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Masao Tasaka - One of the best experts on this subject based on the ideXlab platform.
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a c2h2 type zinc finger protein sgr5 is involved in early events of Gravitropism in arabidopsis inflorescence stems
Plant Journal, 2006Co-Authors: Miyo Terao Morita, Takehide Kato, Keitaro Sakaguchi, Shinichiro Kiyose, Kensuke Taira, Moritaka Nakamura, Masao TasakaAbstract:: Plants can sense the direction of gravity and change the growth orientation of their organs. To elucidate the molecular mechanisms of gravity perception and the signal transduction of Gravitropism, we have characterized a number of shoot Gravitropism (sgr) mutants of Arabidopsis. The sgr5-1 mutant shows reduced Gravitropism in the inflorescence stem but its root and hypocotyl have normal Gravitropism. SGR5 encodes a zinc finger protein with a coiled-coil motif. The SGR5-GFP fusion protein is localized in the nucleus of Arabidopsis protoplasts, suggesting that SGR5 may act as a transcription factor. Analysis of GUS expression under the control of the SGR5 promoter revealed that SGR5 is mainly expressed in the endodermis, the gravity-sensing tissue in inflorescence stems. Furthermore, the observation that endodermis-specific expression of SGR5 using the SCR promoter in the sgr5-1 mutant restores shoot Gravitropism indicates that it could function in the gravity-sensing endodermal cell layer. In contrast to other sgr mutants reported previously, almost all amyloplasts in the endodermal cells of the sgr5-1 mutant sedimented in the direction of gravity. Taken together, our results suggest that SGR5 may be involved in an early event in shoot Gravitropism such as gravity perception and/or a signaling process subsequent to amyloplast sedimentation as a putative transcription factor in gravity-perceptive cells.
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the Gravitropism defective 2 mutants of arabidopsis are deficient in a protein implicated in endocytosis in caenorhabditis elegans
Plant Physiology, 2004Co-Authors: Rebecca A Silady, Masao Tasaka, Takehide Kato, Wolfgang Lukowitz, Patrick Sieber, Chris SomervilleAbstract:The Gravitropism defective 2 (grv2) mutants of Arabidopsis show reduced shoot phototropism and Gravitropism. Amyloplasts in the shoot endodermal cells of grv2 do not sediment to the same degree as in wild type. The GRV2 gene encodes a 277-kD polypeptide that is 42% similar to the Caenorhabditis elegans RME-8 protein, which is required for endocytosis. We hypothesize that a defect in endocytosis may affect both the initial gravity sensing via amyloplasts sedimentation and the subsequent more general tropic growth response.
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a snare complex containing sgr3 atvam3 and zig vti11 in gravity sensing cells is important for arabidopsis shoot Gravitropism
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Daisuke Yano, Miyo Terao Morita, Masakazu Sato, Chieko Saito, Masa H Sato, Masao TasakaAbstract:Plants can sense the direction of gravity and change the growth orientation of their organs. The molecular mechanisms of gravity sensing and signal transduction during Gravitropism are not well known. We have isolated several shoot Gravitropism (sgr) mutants of Arabidopsis. The sgr3-1 mutant exhibits a reduced gravitropic response in the inflorescence stems. In the inflorescence stems of Arabidopsis, gravity is sensed in endodermal cells that contain sedimentable amyloplasts. In sgr3-1, some amyloplasts in the endodermis failed to sediment in the direction of gravity. SGR3 encodes a syntaxin, AtVAM3, which had previously been cloned as a homologue of yeast Vam3p. AtVAM3 is localized to the prevacuolar compartment and vacuole and is suggested to function in vesicle transport to the vacuole. We have also cloned another soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE), ZIG/AtVTI11, a mutation that causes abnormal Gravitropism. This mutant displayed an abnormal distribution of amyloplasts in the endodermal cells similar to that in sgr3-1. Endodermis-specific expression of SGR3 and ZIG by using the SCR promoter could complement the abnormal shoot Gravitropism of each mutant. Protein–protein interaction between AtVAM3 and AtVTI11 in the endodermal cells was detected immunologically. The sgr3-1 mutation appeared to reduce the affinity of AtVAM3 for AtVTI11 or SYP5. These results suggest that vesicle transport to the prevacuolar compartment/vacuole in the endodermal cells, mediated by a specific SNARE complex containing AtVAM3 and AtVTI11, plays an important role in shoot Gravitropism.
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Role of endodermal cell vacuoles in shoot Gravitropism
Journal of Plant Growth Regulation, 2002Co-Authors: Takehide Kato, Miyo Terao Morita, Masao TasakaAbstract:In higher plants, shoots and roots show negative and positive Gravitropism, respectively. Data from surgical ablation experiments and analysis of starch deficient mutants have led to the suggestion that columella cells in the root cap function as gravity perception cells. On the other hand, endodermal cells are believed to be the statocytes (that is, gravity perceiving cells) of shoots. Statocytes in shoots and roots commonly contain amyloplasts which sediment under gravity. Through genetic research with Arabidopsis shoot Gravitropism mutants, sgr1/scr and sgr7/shr, it was determined that endodermal cells are essential for shoot Gravitropism. Moreover, some starch biosynthesis genes and EAL1 are important for the formation and maturation of amyloplasts in shoot endodermis. Thus, amyloplasts in the shoot endodermis would function as statoliths, just as in roots. The study of the sgr2 and zig/sgr4 mutants provides new insights into the early steps of shoot Gravitropism, which still remains unclear. SGR2 and ZIG/SGR4 genes encode a phospholipase-like and a v-SNARE protein, respectively. Moreover, these genes are involved in vacuolar formation or function. Thus, the vacuole must play an important role in amyloplast sedimentation because the sgr2 and zig/sgr4 mutants display abnormal amyloplast sedimentation.
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SGR2, a Phospholipase-Like Protein, and ZIG/SGR4, a SNARE, Are Involved in the Shoot Gravitropism of Arabidopsis
The Plant Cell, 2002Co-Authors: Takehide Kato, Hidehiro Fukaki, Miyo Terao Morita, Yoshiro Yamauchi, Michiko Uehara, Mitsuru Niihama, Masao TasakaAbstract:In higher plants, the shoot and the root generally show negative and positive Gravitropism, respectively. To elucidate the molecular mechanisms involved in Gravitropism, we have isolated many shoot Gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal Gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid–preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot Gravitropism.
Takehide Kato - One of the best experts on this subject based on the ideXlab platform.
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a c2h2 type zinc finger protein sgr5 is involved in early events of Gravitropism in arabidopsis inflorescence stems
Plant Journal, 2006Co-Authors: Miyo Terao Morita, Takehide Kato, Keitaro Sakaguchi, Shinichiro Kiyose, Kensuke Taira, Moritaka Nakamura, Masao TasakaAbstract:: Plants can sense the direction of gravity and change the growth orientation of their organs. To elucidate the molecular mechanisms of gravity perception and the signal transduction of Gravitropism, we have characterized a number of shoot Gravitropism (sgr) mutants of Arabidopsis. The sgr5-1 mutant shows reduced Gravitropism in the inflorescence stem but its root and hypocotyl have normal Gravitropism. SGR5 encodes a zinc finger protein with a coiled-coil motif. The SGR5-GFP fusion protein is localized in the nucleus of Arabidopsis protoplasts, suggesting that SGR5 may act as a transcription factor. Analysis of GUS expression under the control of the SGR5 promoter revealed that SGR5 is mainly expressed in the endodermis, the gravity-sensing tissue in inflorescence stems. Furthermore, the observation that endodermis-specific expression of SGR5 using the SCR promoter in the sgr5-1 mutant restores shoot Gravitropism indicates that it could function in the gravity-sensing endodermal cell layer. In contrast to other sgr mutants reported previously, almost all amyloplasts in the endodermal cells of the sgr5-1 mutant sedimented in the direction of gravity. Taken together, our results suggest that SGR5 may be involved in an early event in shoot Gravitropism such as gravity perception and/or a signaling process subsequent to amyloplast sedimentation as a putative transcription factor in gravity-perceptive cells.
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the Gravitropism defective 2 mutants of arabidopsis are deficient in a protein implicated in endocytosis in caenorhabditis elegans
Plant Physiology, 2004Co-Authors: Rebecca A Silady, Masao Tasaka, Takehide Kato, Wolfgang Lukowitz, Patrick Sieber, Chris SomervilleAbstract:The Gravitropism defective 2 (grv2) mutants of Arabidopsis show reduced shoot phototropism and Gravitropism. Amyloplasts in the shoot endodermal cells of grv2 do not sediment to the same degree as in wild type. The GRV2 gene encodes a 277-kD polypeptide that is 42% similar to the Caenorhabditis elegans RME-8 protein, which is required for endocytosis. We hypothesize that a defect in endocytosis may affect both the initial gravity sensing via amyloplasts sedimentation and the subsequent more general tropic growth response.
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Role of endodermal cell vacuoles in shoot Gravitropism
Journal of Plant Growth Regulation, 2002Co-Authors: Takehide Kato, Miyo Terao Morita, Masao TasakaAbstract:In higher plants, shoots and roots show negative and positive Gravitropism, respectively. Data from surgical ablation experiments and analysis of starch deficient mutants have led to the suggestion that columella cells in the root cap function as gravity perception cells. On the other hand, endodermal cells are believed to be the statocytes (that is, gravity perceiving cells) of shoots. Statocytes in shoots and roots commonly contain amyloplasts which sediment under gravity. Through genetic research with Arabidopsis shoot Gravitropism mutants, sgr1/scr and sgr7/shr, it was determined that endodermal cells are essential for shoot Gravitropism. Moreover, some starch biosynthesis genes and EAL1 are important for the formation and maturation of amyloplasts in shoot endodermis. Thus, amyloplasts in the shoot endodermis would function as statoliths, just as in roots. The study of the sgr2 and zig/sgr4 mutants provides new insights into the early steps of shoot Gravitropism, which still remains unclear. SGR2 and ZIG/SGR4 genes encode a phospholipase-like and a v-SNARE protein, respectively. Moreover, these genes are involved in vacuolar formation or function. Thus, the vacuole must play an important role in amyloplast sedimentation because the sgr2 and zig/sgr4 mutants display abnormal amyloplast sedimentation.
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SGR2, a Phospholipase-Like Protein, and ZIG/SGR4, a SNARE, Are Involved in the Shoot Gravitropism of Arabidopsis
The Plant Cell, 2002Co-Authors: Takehide Kato, Hidehiro Fukaki, Miyo Terao Morita, Yoshiro Yamauchi, Michiko Uehara, Mitsuru Niihama, Masao TasakaAbstract:In higher plants, the shoot and the root generally show negative and positive Gravitropism, respectively. To elucidate the molecular mechanisms involved in Gravitropism, we have isolated many shoot Gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal Gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid–preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot Gravitropism.
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sgr2 a phospholipase like protein and zig sgr4 a snare are involved in the shoot Gravitropism of arabidopsis
The Plant Cell, 2002Co-Authors: Takehide Kato, Hidehiro Fukaki, Miyo Terao Morita, Yoshiro Yamauchi, Michiko Uehara, Mitsuru Niihama, Masao TasakaAbstract:In higher plants, the shoot and the root generally show negative and positive Gravitropism, respectively. To elucidate the molecular mechanisms involved in Gravitropism, we have isolated many shoot Gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal Gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid–preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot Gravitropism.
Miyo Terao Morita - One of the best experts on this subject based on the ideXlab platform.
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gravity sensing tissues for Gravitropism are required for anti gravitropic phenotypes of lzy multiple mutants in arabidopsis
Plants (Basel Switzerland), 2020Co-Authors: Nozomi Kawamoto, Moritaka Nakamura, Yuta Kanbe, Akiko Mori, Miyo Terao MoritaAbstract:Plant posture is controlled by various environmental cues, such as light, temperature, and gravity. The overall architecture is determined by the growth angles of lateral organs, such as roots and branches. The branch growth angle affected by gravity is known as the gravitropic setpoint angle (GSA), and it has been proposed that the GSA is determined by balancing two opposing growth components: Gravitropism and anti-gravitropic offset (AGO). The molecular mechanisms underlying Gravitropism have been studied extensively, but little is known about the nature of the AGO. Recent studies reported the importance of LAZY1-LIKE (LZY) family genes in the signaling process for Gravitropism, such that loss-of-function mutants of LZY family genes resulted in reversed Gravitropism, which we term it here as the “anti-gravitropic” phenotype. We assume that this peculiar phenotype manifests as the AGO due to the loss of Gravitropism, we characterized the “anti-gravitropic” phenotype of Arabidopsis lzy multiple mutant genetically and physiologically. Our genetic interaction analyses strongly suggested that gravity-sensing cells are required for the “anti-gravitropic” phenotype in roots and lateral branches. We also show that starch-filled amyloplasts play a significant role in the “anti-gravitropic” phenotype, especially in the root of the lzy multiple mutant.
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Bridging the gap between amyloplasts and directional auxin transport in plant Gravitropism
Current Opinion in Plant Biology, 2019Co-Authors: Moritaka Nakamura, Takeshi Nishimura, Miyo Terao MoritaAbstract:Gravitropism is the directional control of plant organ growth in response to gravity. Specialized gravity-sensing cells contain amyloplasts that can change their position according to the direction of gravity. Gravity signaling, which is elicited by the relocation of amyloplasts, is a key process that redirects auxin transport from gravity-sensing cells to the lower flank of gravity-responsive organs. Despite the long history of research on plant Gravitropism, a molecular detail of gravity signaling remained unexplained. Recent studies have characterized the Arabidopsis LAZY1 family genes to be key factors of gravity signaling. Furthermore, studies regarding Arabidopsis AGCVIII kinases have demonstrated the requirement of auxin transporter PIN-FORMED3 (PIN3) phosphorylation in plant Gravitropism.
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a c2h2 type zinc finger protein sgr5 is involved in early events of Gravitropism in arabidopsis inflorescence stems
Plant Journal, 2006Co-Authors: Miyo Terao Morita, Takehide Kato, Keitaro Sakaguchi, Shinichiro Kiyose, Kensuke Taira, Moritaka Nakamura, Masao TasakaAbstract:: Plants can sense the direction of gravity and change the growth orientation of their organs. To elucidate the molecular mechanisms of gravity perception and the signal transduction of Gravitropism, we have characterized a number of shoot Gravitropism (sgr) mutants of Arabidopsis. The sgr5-1 mutant shows reduced Gravitropism in the inflorescence stem but its root and hypocotyl have normal Gravitropism. SGR5 encodes a zinc finger protein with a coiled-coil motif. The SGR5-GFP fusion protein is localized in the nucleus of Arabidopsis protoplasts, suggesting that SGR5 may act as a transcription factor. Analysis of GUS expression under the control of the SGR5 promoter revealed that SGR5 is mainly expressed in the endodermis, the gravity-sensing tissue in inflorescence stems. Furthermore, the observation that endodermis-specific expression of SGR5 using the SCR promoter in the sgr5-1 mutant restores shoot Gravitropism indicates that it could function in the gravity-sensing endodermal cell layer. In contrast to other sgr mutants reported previously, almost all amyloplasts in the endodermal cells of the sgr5-1 mutant sedimented in the direction of gravity. Taken together, our results suggest that SGR5 may be involved in an early event in shoot Gravitropism such as gravity perception and/or a signaling process subsequent to amyloplast sedimentation as a putative transcription factor in gravity-perceptive cells.
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a snare complex containing sgr3 atvam3 and zig vti11 in gravity sensing cells is important for arabidopsis shoot Gravitropism
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Daisuke Yano, Miyo Terao Morita, Masakazu Sato, Chieko Saito, Masa H Sato, Masao TasakaAbstract:Plants can sense the direction of gravity and change the growth orientation of their organs. The molecular mechanisms of gravity sensing and signal transduction during Gravitropism are not well known. We have isolated several shoot Gravitropism (sgr) mutants of Arabidopsis. The sgr3-1 mutant exhibits a reduced gravitropic response in the inflorescence stems. In the inflorescence stems of Arabidopsis, gravity is sensed in endodermal cells that contain sedimentable amyloplasts. In sgr3-1, some amyloplasts in the endodermis failed to sediment in the direction of gravity. SGR3 encodes a syntaxin, AtVAM3, which had previously been cloned as a homologue of yeast Vam3p. AtVAM3 is localized to the prevacuolar compartment and vacuole and is suggested to function in vesicle transport to the vacuole. We have also cloned another soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE), ZIG/AtVTI11, a mutation that causes abnormal Gravitropism. This mutant displayed an abnormal distribution of amyloplasts in the endodermal cells similar to that in sgr3-1. Endodermis-specific expression of SGR3 and ZIG by using the SCR promoter could complement the abnormal shoot Gravitropism of each mutant. Protein–protein interaction between AtVAM3 and AtVTI11 in the endodermal cells was detected immunologically. The sgr3-1 mutation appeared to reduce the affinity of AtVAM3 for AtVTI11 or SYP5. These results suggest that vesicle transport to the prevacuolar compartment/vacuole in the endodermal cells, mediated by a specific SNARE complex containing AtVAM3 and AtVTI11, plays an important role in shoot Gravitropism.
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Role of endodermal cell vacuoles in shoot Gravitropism
Journal of Plant Growth Regulation, 2002Co-Authors: Takehide Kato, Miyo Terao Morita, Masao TasakaAbstract:In higher plants, shoots and roots show negative and positive Gravitropism, respectively. Data from surgical ablation experiments and analysis of starch deficient mutants have led to the suggestion that columella cells in the root cap function as gravity perception cells. On the other hand, endodermal cells are believed to be the statocytes (that is, gravity perceiving cells) of shoots. Statocytes in shoots and roots commonly contain amyloplasts which sediment under gravity. Through genetic research with Arabidopsis shoot Gravitropism mutants, sgr1/scr and sgr7/shr, it was determined that endodermal cells are essential for shoot Gravitropism. Moreover, some starch biosynthesis genes and EAL1 are important for the formation and maturation of amyloplasts in shoot endodermis. Thus, amyloplasts in the shoot endodermis would function as statoliths, just as in roots. The study of the sgr2 and zig/sgr4 mutants provides new insights into the early steps of shoot Gravitropism, which still remains unclear. SGR2 and ZIG/SGR4 genes encode a phospholipase-like and a v-SNARE protein, respectively. Moreover, these genes are involved in vacuolar formation or function. Thus, the vacuole must play an important role in amyloplast sedimentation because the sgr2 and zig/sgr4 mutants display abnormal amyloplast sedimentation.
Hidehiro Fukaki - One of the best experts on this subject based on the ideXlab platform.
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SGR2, a Phospholipase-Like Protein, and ZIG/SGR4, a SNARE, Are Involved in the Shoot Gravitropism of Arabidopsis
The Plant Cell, 2002Co-Authors: Takehide Kato, Hidehiro Fukaki, Miyo Terao Morita, Yoshiro Yamauchi, Michiko Uehara, Mitsuru Niihama, Masao TasakaAbstract:In higher plants, the shoot and the root generally show negative and positive Gravitropism, respectively. To elucidate the molecular mechanisms involved in Gravitropism, we have isolated many shoot Gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal Gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid–preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot Gravitropism.
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sgr2 a phospholipase like protein and zig sgr4 a snare are involved in the shoot Gravitropism of arabidopsis
The Plant Cell, 2002Co-Authors: Takehide Kato, Hidehiro Fukaki, Miyo Terao Morita, Yoshiro Yamauchi, Michiko Uehara, Mitsuru Niihama, Masao TasakaAbstract:In higher plants, the shoot and the root generally show negative and positive Gravitropism, respectively. To elucidate the molecular mechanisms involved in Gravitropism, we have isolated many shoot Gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal Gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid–preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot Gravitropism.
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genetic regulation of Gravitropism in higher plants
International Review of Cytology-a Survey of Cell Biology, 2001Co-Authors: Masao Tasaka, Takehide Kato, Hidehiro FukakiAbstract:Abstract Gravitropism is a classical subject in plant physiology. However, the molecular mechanisms that regulate Gravitropism are unknown. Recently, many gravitropic mutants have been isolated from Arabidopsis thaliana and several genes for Gravitropism have been cloned and characterized. These studies have shown that (1) the endodermis is essential for shoot Gravitropism and (2) an auxin transport system and signaling pathway are necessary for Gravitropism. Recent studies in Arabidopsis are reviewed and genetic regulation of Gravitropism in this organism is discussed.
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the endodermis and shoot Gravitropism
Trends in Plant Science, 1999Co-Authors: Masao Tasaka, Takehide Kato, Hidehiro FukakiAbstract:Abstract Shoots and roots of higher plants exhibit negative and positive Gravitropism, respectively. A variety of gravitropic mutants have recently been isolated from Arabidopsis , the characterization of which demonstrates that the molecular mechanisms of the gravitropic responses in roots, hypocotyls and inflorescence stems are different. The cytological and molecular analysis of two mutants, shoot Gravitropism 1 ( sgr1 ), which is allelic to scarecrow ( scr ), and sgr7 , which is allelic to short-root ( shr ), indicate that the endodermis is the site of gravity perception in shoots. These data suggest a new model for shoot Gravitropism.
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Genetic evidence that the endodermis is essential for shoot Gravitropism in Arabidopsis thaliana
Plant Journal, 1998Co-Authors: Hidehiro Fukaki, Hisao Fujisawa, Takehide Kato, Philip N Benfey, Joanna Wysocka-diller, Masao TasakaAbstract:Shoots of higher plants exhibit negative Gravitropism. However, little is known about the mechanism or site of gravity perception in shoots. We have identified two loci that are essential for normal shoot Gravitropism in Arabidopsis thaliana. Genetic analysis demonstrated that the shoot Gravitropism mutants sgr1 and sgr7 are allelic to the radial pattern mutants, scr and shr, respectively. Characterization of the aerial phenotype of these mutants revealed that the primary defect is the absence of a normal endodermis in hypocotyls and influorescence stems. This indicates that the endodermis is essential for shoot Gravitropism and strongly suggests that this cell layer functions as the gravity-sensing cell layer in dicotyledonous plant shoots. These results also demonstrate that, in addition to their previously characterized role in root radial patterning, SCR and SHR regulate the radial organization of the shoot axial organs in Arabidopsis.
Patrick Masson - One of the best experts on this subject based on the ideXlab platform.
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gravity sensing and signal transduction in vascular plant primary roots
American Journal of Botany, 2013Co-Authors: Katherine L Baldwin, Allison K Strohm, Patrick MassonAbstract:During Gravitropism, the potential energy of gravity is converted into a biochemical signal. How this transfer occurs remains one of the most exciting mysteries in plant cell biology. New experiments are filling in pieces of the puzzle. In this review, we introduce Gravitropism and give an overview of what we know about gravity sensing in roots of vascular plants, with special highlight on recent papers. When plant roots are reoriented sideways, amyloplast resedimentation in the columella cells is a key initial step in gravity sensing. This process somehow leads to cytoplasmic alkalinization of these cells followed by relocalization of auxin efflux carriers (PINs). This changes auxin flow throughout the root, generating a lateral gradient of auxin across the cap that upon transmission to the elongation zone leads to differential cell elongation and gravibending. We will present the evidence for and against the following players having a role in transferring the signal from the amyloplast sedimentation into the auxin signaling cascade: mechanosensitive ion channels, actin, calcium ions, inositol trisphosphate, receptors/ligands, ARG1/ARL2, spermine, and the TOC complex. We also outline auxin transport and signaling during Gravitropism.
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root Gravitropism an experimental tool to investigate basic cellular and molecular processes underlying mechanosensing and signal transmission in plants
Annual Review of Plant Biology, 2002Co-Authors: Kanokporn Boonsirichai, Rujin Chen, Changhui Guan, Patrick MassonAbstract:▪ Abstract The ability of plant organs to use gravity as a guide for growth, named Gravitropism, has been recognized for over two centuries. This growth response to the environment contributes significantly to the upward growth of shoots and the downward growth of roots commonly observed throughout the plant kingdom. Root Gravitropism has received a great deal of attention because there is a physical separation between the primary site for gravity sensing, located in the root cap, and the site of differential growth response, located in the elongation zones (EZs). Hence, this system allows identification and characterization of different phases of Gravitropism, including gravity perception, signal transduction, signal transmission, and curvature response. Recent studies support some aspects of an old model for gravity sensing, which postulates that root-cap columellar amyloplasts constitute the susceptors for gravity perception. Such studies have also allowed the identification of several molecules that a...
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root Gravitropism a complex response to a simple stimulus
Trends in Plant Science, 1999Co-Authors: Elizabeth Rosen, Rujin Chen, Patrick MassonAbstract:Abstract Roots avoid depleting their immediate environment of essential nutrients by continuous growth. Root growth is directed by environmental cues, including gravity. Gravity sensing occurs mainly in the columella cells of the root cap. Upon reorientation within the gravity field, the root-cap amyloplasts sediment, generating a physiological signal that promotes the development of a curvature at the root elongation zones. Recent molecular genetic studies in Arabidopsis have allowed the identification of genes that play important roles in root Gravitropism. Among them, the ARG1 gene encodes a DnaJ-like protein involved in gravity signal transduction, whereas the AUX1 and AGR1 genes encode proteins involved in polar auxin transport. These studies have important implications for understanding the intra- and inter-cellular signaling processes that underlie root Gravitropism.
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Update on Development Gravitropism in Higher Plants 1
1999Co-Authors: Rujin Chen, Elizabeth Rosen, Patrick MassonAbstract:Since 1806, we have known that plant organs use gravity as a guide for growth (Knight, 1806). The gravity-directed growth process, called Gravitropism, dictates upward shoot growth to ensure a proper positioning of the leaves for efficient photosynthesis and gas exchange. It also directs roots to grow downward in soil, where they can reach out to take up the water and mineral ions required for plant growth and development. Gravitropism has an important impact on agriculture. It allows plants to compete for the limited resources available in their immediate environment and ensures that crop shoots resume upward growth after prostration by the action of wind and rain (Fig. 1). Consequently, plants can keep their seeds away from soil moisture and pathogens and are more amenable to mechanical harvesting. At the end of the 19th century, Ciesielski (1872) and Darwin (1880) demonstrated that a structure at the tip of the roots, the cap, is essential for root Gravitropism. They postulated that the root cap could perceive a change in root-tip orientation within the gravitational field (gravistimulus). Graviperception would then produce a physiological signal that, upon transmission to the elongation zone, would promote a differential cellular elongation on opposite flanks, which is responsible for the development of a curvature. The resulting curvature would allow the root tip to resume growth along a gravitropically more acceptable vector. These important early observations along with the proposed model for gravity perception marked the beginning of numerous studies that extended throughout the entire 20th century and helped us to gain a better understanding of the various physiological and molecular processes underlying Gravitropism. In this Update we discuss our current knowledge of the gravitropic response of higher plants, with a special emphasis on roots.
