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Yoshihiro Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Sudden Collapse of Vacuoles in Saintpaulia sp. Palisade Cells Induced by a Rapid Temperature Decrease
2016Co-Authors: Noriaki Kadohama, Tatsuaki Goh, Miwa Ohnishi, Hidehiro Fukaki, Tetsuro Mimura, Yoshihiro SuzukiAbstract:It is well known that Saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in Saintpaulia (Saintpaulia sp. cv. ‘Iceberg’) and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cell
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Involvement of Ca2+ in Vacuole Degradation Caused by a Rapid Temperature Decrease in Saintpaulia Palisade Cells: A Case of Gene Expression Analysis in a Specialized Small Tissue
Plant & cell physiology, 2015Co-Authors: Miwa Ohnishi, Noriaki Kadohama, Hidehiro Fukaki, Yoshihiro Suzuki, Tomoharu Kajiyama, Chizuko Shichijo, Kimitsune Ishizaki, Hidetoshi Iida, Hideki Kambara, Tetsuro MimuraAbstract:Saintpaulia (African violet) leaves are known to be damaged by a rapid temperature decrease when cold water is applied to the leaf surface; the injury is ascribed to the chloroplast damage caused by the cytosolic pH decrease following the degradation of the vacuolar membrane in the palisade cells. In this report, we present evidence for the involvement of Ca(2+) in facilitating the collapse of the vacuolar membrane and in turn in the temperature sensitivity of Saintpaulia leaves. In the presence of a Ca(2+) chelator (EGTA) or certain Ca(2+) channel inhibitors (Gd(3+) or La(3+)) but not others (verapamil or nifedipine), the pH of the vacuole, monitored through BCECF (2',7'-bis(carboxyethyl)-4 or 5-carboxyfluorescein) fluorescence, did not increase in response to a rapid temperature drop. These pharmacological observations are consistent with the involvement of mechanosensitive Ca(2+) channels in the collapse of the vacuolar membrane. The high level of expression of an MCA- (Arabidopsis mechanosensitive Ca(2+) channel) like gene, a likely candidate for a mechanosensitive Ca(2+) channel(s) in plant cells, was confirmed in the palisade tissue in Saintpaulia leaves by using a newly developed method of gene expression analysis for the specialized small tissues.
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Involvement of Ca2+ in vacuole degradation caused by a rapid temperature decrease in Saintpaulia palisade cells: A case of gene expression analysis in a specialized small tissue. Plant Cell Physiol
2015Co-Authors: Miwa Ohnishi, Noriaki Kadohama, Hidehiro Fukaki, Yoshihiro Suzuki, Tomoharu Kajiyama, Chizuko Shichijo, Kimitsune Ishizaki, Hidetoshi Iida, Hideki Kambara, Tetsuro MimuraAbstract:Saintpaulia (African violet) leaves are known to be damaged by a rapid temperature decrease when cold water is applied to the leaf surface; the injury is ascribed to the chloroplast damage caused by the cytosolic pH decrease following the degradation of the vacuolar membrane in the palisade cells. In this report, we present evidence for the involvement of Ca2+ in facilitating the collapse of the vacuolar membrane and in turn in the temperature sensitivity of Saintpaulia leaves. In the presence of a Ca2+ chelator (EGTA) or certain Ca2+ channel inhibitors (Gd3+ or La3+) but not others (ver-apamil or nifedipine), the pH of the vacuole, monitored through BCECF (20,70-bis(carboxyethyl)-4 or 5-carboxyfluor-escein) fluorescence, did not increase in response to a rapid temperature drop. These pharmacological observations are consistent with the involvement of mechanosensitive Ca2
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Sudden collapse of vacuoles in Saintpaulia sp. palisade cells induced by a rapid temperature decrease.
PloS one, 2013Co-Authors: Noriaki Kadohama, Tatsuaki Goh, Miwa Ohnishi, Hidehiro Fukaki, Tetsuro Mimura, Yoshihiro SuzukiAbstract:It is well known that Saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in Saintpaulia (Saintpaulia sp. cv. ‘Iceberg’) and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury.
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List of Gesneriaceae species used in this study and GenBank accession numbers for their ribosomal internal transcribed spacer 1 (ITS1) sequences.
2013Co-Authors: Noriaki Kadohama, Tatsuaki Goh, Miwa Ohnishi, Hidehiro Fukaki, Tetsuro Mimura, Yoshihiro SuzukiAbstract:aSaintpaulia cultivars are mainly derived from the original species Saintpaulia ionantha[23]. Therefore, we used the ITS 1 sequence of Saintpaulia ionantha to estimate the position of cv. “Iceberg” in the phylogenetic trees.
Quentin C. B. Cronk - One of the best experts on this subject based on the ideXlab platform.
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Evolution and Development of Floral Diversity in Streptocarpus and Saintpaulia
Annals of Botany, 1999Co-Authors: C. Jill Harrison, Michael Moller, Quentin C. B. CronkAbstract:Abstract Floral diversity in Streptocarpus and Saintpaulia can be classified into six distinct types on the basis of quantitative variation. Species are differentiated by overall flower size and by corolla lobe size in relation to corolla tube opening size, characteristics implicated in pollination ecology. Saintpaulia has a very short corolla tube and yellow protruding anthers, strikingly different from Streptocarpus , and probably associated with buzz pollination. Some species of Streptocarpus and all species of Saintpaulia are enantiostylous, a feature often linked to buzz pollination. Mapping of these floral characters onto a molecular phylogeny based on ITS sequence data showed that inStreptocarpus flower size evolved from small to large, with reversals in four species. The putatively bee pollinated ‘open-tubed’ type had two independent origins, and the putatively lepidopteran-pollinated ‘keyhole’ type had four separate origins. Enantiostyly had one or two origins. The degree of zygomorphy varies withinStreptocarpus/Saintpaulia. The most extreme difference is between Saintpaulia ionantha and aSaintpaulia peloric cultivar. The developmental basis of floral variation was compared using SEM in three very different types: Streptocarpus primulifolius, Saintpaulia ionantha and a Saintpaulia peloric cultivar. Differences in corolla tube length and zygomorphy are established very early in flower development. Small, early changes in flower development establish major changes in mature floral morphology.
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Phylogeny and disjunct distribution: evolution of Saintpaulia (Gesneriaceae).
Proceedings of The Royal Society B: Biological Sciences, 1997Co-Authors: Michael Moller, Quentin C. B. CronkAbstract:The molecular phylogeny of African violets (Saintpaulia H. Wendl.), based on ribosomal DNA internal transcribed spacer (ITS) sequences, follows the disjunct biogeography of the genus. Sequence anal...
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origin and relationships of Saintpaulia gesneriaceae based on ribosomal dna internal transcribed spacer its sequences
American Journal of Botany, 1997Co-Authors: Michael Moller, Quentin C. B. CronkAbstract:Phylogenetic relationships of eight species of Saintpaulia H. Wendl., 19 species of Streptocarpus Lindl. (representing all major growth forms within the genus), and two outgroups (Haberlea rhodopensisFriv., Chirita spadiciformis W. T. Wang) were examined using comparative nucleotide sequences from the two internal transcribed spacers (ITS) of nuclear ribosomal DNA. The length of the ITS 1 region ranged from 228 to 249 base pairs (bp) and the ITS 2 region from 196 to 245 bp. Pairwise sequence divergence across both spacers for ingroup and outgroup species ranged from 0 to 29%. Streptocarpus is not monophyletic, and Saintpaulia is nested within Streptocarpus subgenus Streptocarpella. Streptocarpus subgenus Streptocarpus is monophyletic. The ITS sequence data demonstrate that the unifoliate Streptocarpus species form a clade, and are also characterized by a unique 47-bp deletion in ITS 2. The results strongly support the monophyly of (1) Saintpaulia, and (2) Saintpaulia plus the African members of the subgenus Streptocarpella of Streptocarpus. The data suggest the evolution of Saintpaulia from Streptocarpus subgenus Streptocarpella. The differences in flower and vegetative characters are probably due to ecological adaptation leading to a relatively rapid radiation of Saintpaulia. The genus Saintpaulia (Gesneriaceae, subfamily Cyrtandroideae) is endemic to Eastern Africa. It forms a geographically restricted aggregate of ;20 species ranging from the Teita Hills in the south of Kenya to the Uluguru Mountains in eastern Tanzania, with the center of species diversity being the Usambara Mountains of northeast Tanzania (Burtt, 1958). Saintpaulia species were first introduced to cultivation in Europe in 1892 by Baron Walter von Saint Paul, and within years became a popular house plant, and are now the basis of a large horticultural industry (Robey, 1988). The relationships of Saintpaulia to other genera of Gesneriaceae have been disputed. This is partly a result of the genus being characterized by an almost rotate corolla and the near absence of a corolla tube, which are comparatively unusual features in the Gesneriaceae, although they occur in a few other species, such as Boea, Petrocosmea, Platystemma, and Ramonda. Ivanina (1966) even suggested that Saintpaulia occupied its own tribe, Saintpaulieae. However, Hilliard and Burtt (1971, pp. 114‐115) wrote: ‘‘Until re1
Motoaki Doi - One of the best experts on this subject based on the ideXlab platform.
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The histological study in sympetalous corolla development of pinwheel-type flowers of Saintpaulia
Scientia Horticulturae, 2017Co-Authors: Soo-jung Yang, Sho Ohno, Ayumi Deguchi, Mitsuru Sato, Mariko Goto, Motoaki Doi, Miki Ohnishi, Fumi Tatsuzawa, Munetaka HosokawaAbstract:Abstract In this study, we revealed how the petals of Saintpaulia fuse into a corolla by using pinwheel phenotype cultivars. Striped patterns in petal, called pinwheel in Saintpaulia, are attractive phenotypes and thought to be the result of periclinal chimerism. For the selection of a genuine periclinal chimeric cultivar from three pinwheel cultivars, adventitious shoots were induced from leaf lamina. Shoot regeneration was observed from the epidermis in all cultivars by microscopic observation. All regenerated shoots from ‘Kaname’ flowered as monochromatic pink flowers, corresponding to an L1 phenotype of the cultivar. From the other two cultivars, many shoots flowered not only as an epidermal phenotype but also as a phenotype of the inner layer. In addition, shoot regeneration was induced from epidermis-peeled petioles from these three cultivars. All shoots from ‘Kaname’ flowered as monochromatic blue flowers, corresponding to an L2 phenotype. On the other hand, many shoots from ‘Kilauea’ flowered not only as monochromatic flowers, corresponding to an L2 phenotype, but also as bi-colored flowers. ‘Innocent Pink’ did not produce shoots from epidermal-peeled petioles. These results suggested that ‘Kaname’ is a genuine periclinal chimera, while the other two cultivars have other mechanisms for pinwheel expression. Genomic PCR using primers that amplifies almost the full length of flavonoid 3′,5′-hydroxylase (F3ʹ5ʹH) revealed the gene to be non-functional in pink flowers from L1 of ‘Kaname’. From monochromatic pink plants and pink portions of the corolla of ‘Kaname’, full-length F3ʹ5ʹH was not amplified. Similar results were obtained by quantitative PCR. Finally, we observed the fused portion of the petals and revealed that the petal fusion did not occur by postgenital fusion but by “connection”. The process, in Saintpaulia, comprises periclinal cell division in L1 during petal development, active cell division at the edge of the petal, adhesion to the next petals, and fusion. These steps create a striped flower color in Saintpaulia.
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Somaclonal Variation Is Induced De Novo via the Tissue Culture Process: A Study Quantifying Mutated Cells in Saintpaulia
PloS one, 2011Co-Authors: Mitsuru Sato, Munetaka Hosokawa, Motoaki DoiAbstract:Background The origin of somaclonal variation has not been questioned previously, i.e., “pre-existing mutations” in explants and “newly induced mutations” arising from the tissue culture process have not been distinguished. This is primarily because there has been no reliable molecular method for estimating or quantifying variation. Methodology/Principal Findings We adopted a petal-variegated cultivar of Saintpaulia ‘Thamires’ (Saintpaulia sp.) as the model plant. Based on the difference between the pre- and post-transposon excision sequence of the promoter region of flavonoid 3′, 5′-hydoroxylase (F3′5′H), we estimated mutated (transposon-excised) cell percentages using a quantitative real-time PCR. Mutated cell percentages in leaf laminae used as explants was 4.6 and 2.4% in highly or low variegation flower plants, respectively, although the occurrences of blue color mutants in their regenerants were more than 40%. Preexisting mutated cell percentages in cultured explants were considerably lower than the mutated plant percentage among total regenerants via tissue culture. Conclusions/Significance The estimation of mutated cell percentages became possible using the quantitative real-time PCR. The origins of mutations were successfully distinguished; it was confirmed that somaclonal variations are mainly caused by newly generated mutations arising from tissue culture process.
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Tissue culture-induced flower-color changes in Saintpaulia caused by excision of the transposon inserted in the flavonoid 3′, 5′ hydroxylase (F3′5′H) promoter
Plant cell reports, 2011Co-Authors: Mitsuru Sato, Munetaka Hosokawa, Fumi Tatsuzawa, Takashi Kawabe, Motoaki DoiAbstract:The variegated Saintpaulia cultivar Thamires (Saintpaulia sp.), which has pink petals with blue splotches, is generally maintained by leaf cuttings. In contrast, tissue culture-derived progeny of the cultivar showed not only a high percentage of mutants with solid-blue petals but also other solid-color variants, which have not been observed from leaf cuttings. Solid-color phenotypes were inherited stably by their progeny from tissue culture. Petals from each solid-color variant were analyzed by high-performance liquid chromatography and shown to contain different proportions of three main anthocyanin derivatives: malvidin, peonidin, and pelargonidin. Analysis of flavonoid 3′, 5′-hydroxylase (F3′5′H) sequences showed no differences in the coding region among the variants and variegated individuals. However, a transposon belonging to the hAT superfamily was found in the promoter region of variegated individuals, and the presence of transposon-related insertions or deletions correlated with the observed flower-color phenotypes. Solid-blue flower mutants contained 8-base pair (bp) insertions (transposon excision footprints), while solid-pink mutants had 58- to 70-bp insertions, and purple- and deep-purple mutants had 21- and 24-bp deletions, respectively. Real-time reverse transcription polymerase chain reaction (RT–PCR) analysis showed that F3′5′H expression levels correlated with insertions and deletions (indels) caused by hAT excision, resulting in flower-color differences. Our results showed that tissue culture of Saintpaulia ‘Thamires’ elicits transposon excision, which in turn alters F3′5′H expression levels and flower colors.
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tissue culture induced flower color changes in Saintpaulia caused by excision of the transposon inserted in the flavonoid 3 5 hydroxylase f3 5 h promoter
Plant Cell Reports, 2011Co-Authors: Mitsuru Sato, Munetaka Hosokawa, Fumi Tatsuzawa, Takashi Kawabe, Motoaki DoiAbstract:The variegated Saintpaulia cultivar Thamires (Saintpaulia sp.), which has pink petals with blue splotches, is generally maintained by leaf cuttings. In contrast, tissue culture-derived progeny of the cultivar showed not only a high percentage of mutants with solid-blue petals but also other solid-color variants, which have not been observed from leaf cuttings. Solid-color phenotypes were inherited stably by their progeny from tissue culture. Petals from each solid-color variant were analyzed by high-performance liquid chromatography and shown to contain different proportions of three main anthocyanin derivatives: malvidin, peonidin, and pelargonidin. Analysis of flavonoid 3′, 5′-hydroxylase (F3′5′H) sequences showed no differences in the coding region among the variants and variegated individuals. However, a transposon belonging to the hAT superfamily was found in the promoter region of variegated individuals, and the presence of transposon-related insertions or deletions correlated with the observed flower-color phenotypes. Solid-blue flower mutants contained 8-base pair (bp) insertions (transposon excision footprints), while solid-pink mutants had 58- to 70-bp insertions, and purple- and deep-purple mutants had 21- and 24-bp deletions, respectively. Real-time reverse transcription polymerase chain reaction (RT–PCR) analysis showed that F3′5′H expression levels correlated with insertions and deletions (indels) caused by hAT excision, resulting in flower-color differences. Our results showed that tissue culture of Saintpaulia ‘Thamires’ elicits transposon excision, which in turn alters F3′5′H expression levels and flower colors.
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Somaclonal Variation Is Induced De Novo via the Tissue Culture Process: A Study Quantifying Mutated Cells in
2011Co-Authors: Mitsuru Sato, Munetaka Hosokawa, Motoaki DoiAbstract:Background: The origin of somaclonal variation has not been questioned previously, i.e., ‘‘pre-existing mutations’ ’ in explants and ‘‘newly induced mutations’ ’ arising from the tissue culture process have not been distinguished. This is primarily because there has been no reliable molecular method for estimating or quantifying variation. Methodology/Principal Findings: We adopted a petal-variegated cultivar of Saintpaulia ‘Thamires ’ (Saintpaulia sp.) as the model plant. Based on the difference between the pre- and post-transposon excision sequence of the promoter region of flavonoid 39,59-hydoroxylase (F3959H), we estimated mutated (transposon-excised) cell percentages using a quantitative realtime PCR. Mutated cell percentages in leaf laminae used as explants was 4.6 and 2.4 % in highly or low variegation flower plants, respectively, although the occurrences of blue color mutants in their regenerants were more than 40%. Preexisting mutated cell percentages in cultured explants were considerably lower than the mutated plant percentage among total regenerants via tissue culture. Conclusions/Significance: The estimation of mutated cell percentages became possible using the quantitative real-time PCR. The origins of mutations were successfully distinguished; it was confirmed that somaclonal variations are mainl
Tetsuro Mimura - One of the best experts on this subject based on the ideXlab platform.
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Sudden Collapse of Vacuoles in Saintpaulia sp. Palisade Cells Induced by a Rapid Temperature Decrease
2016Co-Authors: Noriaki Kadohama, Tatsuaki Goh, Miwa Ohnishi, Hidehiro Fukaki, Tetsuro Mimura, Yoshihiro SuzukiAbstract:It is well known that Saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in Saintpaulia (Saintpaulia sp. cv. ‘Iceberg’) and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cell
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Involvement of Ca2+ in Vacuole Degradation Caused by a Rapid Temperature Decrease in Saintpaulia Palisade Cells: A Case of Gene Expression Analysis in a Specialized Small Tissue
Plant & cell physiology, 2015Co-Authors: Miwa Ohnishi, Noriaki Kadohama, Hidehiro Fukaki, Yoshihiro Suzuki, Tomoharu Kajiyama, Chizuko Shichijo, Kimitsune Ishizaki, Hidetoshi Iida, Hideki Kambara, Tetsuro MimuraAbstract:Saintpaulia (African violet) leaves are known to be damaged by a rapid temperature decrease when cold water is applied to the leaf surface; the injury is ascribed to the chloroplast damage caused by the cytosolic pH decrease following the degradation of the vacuolar membrane in the palisade cells. In this report, we present evidence for the involvement of Ca(2+) in facilitating the collapse of the vacuolar membrane and in turn in the temperature sensitivity of Saintpaulia leaves. In the presence of a Ca(2+) chelator (EGTA) or certain Ca(2+) channel inhibitors (Gd(3+) or La(3+)) but not others (verapamil or nifedipine), the pH of the vacuole, monitored through BCECF (2',7'-bis(carboxyethyl)-4 or 5-carboxyfluorescein) fluorescence, did not increase in response to a rapid temperature drop. These pharmacological observations are consistent with the involvement of mechanosensitive Ca(2+) channels in the collapse of the vacuolar membrane. The high level of expression of an MCA- (Arabidopsis mechanosensitive Ca(2+) channel) like gene, a likely candidate for a mechanosensitive Ca(2+) channel(s) in plant cells, was confirmed in the palisade tissue in Saintpaulia leaves by using a newly developed method of gene expression analysis for the specialized small tissues.
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Involvement of Ca2+ in vacuole degradation caused by a rapid temperature decrease in Saintpaulia palisade cells: A case of gene expression analysis in a specialized small tissue. Plant Cell Physiol
2015Co-Authors: Miwa Ohnishi, Noriaki Kadohama, Hidehiro Fukaki, Yoshihiro Suzuki, Tomoharu Kajiyama, Chizuko Shichijo, Kimitsune Ishizaki, Hidetoshi Iida, Hideki Kambara, Tetsuro MimuraAbstract:Saintpaulia (African violet) leaves are known to be damaged by a rapid temperature decrease when cold water is applied to the leaf surface; the injury is ascribed to the chloroplast damage caused by the cytosolic pH decrease following the degradation of the vacuolar membrane in the palisade cells. In this report, we present evidence for the involvement of Ca2+ in facilitating the collapse of the vacuolar membrane and in turn in the temperature sensitivity of Saintpaulia leaves. In the presence of a Ca2+ chelator (EGTA) or certain Ca2+ channel inhibitors (Gd3+ or La3+) but not others (ver-apamil or nifedipine), the pH of the vacuole, monitored through BCECF (20,70-bis(carboxyethyl)-4 or 5-carboxyfluor-escein) fluorescence, did not increase in response to a rapid temperature drop. These pharmacological observations are consistent with the involvement of mechanosensitive Ca2
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Sudden collapse of vacuoles in Saintpaulia sp. palisade cells induced by a rapid temperature decrease.
PloS one, 2013Co-Authors: Noriaki Kadohama, Tatsuaki Goh, Miwa Ohnishi, Hidehiro Fukaki, Tetsuro Mimura, Yoshihiro SuzukiAbstract:It is well known that Saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in Saintpaulia (Saintpaulia sp. cv. ‘Iceberg’) and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury.
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List of Gesneriaceae species used in this study and GenBank accession numbers for their ribosomal internal transcribed spacer 1 (ITS1) sequences.
2013Co-Authors: Noriaki Kadohama, Tatsuaki Goh, Miwa Ohnishi, Hidehiro Fukaki, Tetsuro Mimura, Yoshihiro SuzukiAbstract:aSaintpaulia cultivars are mainly derived from the original species Saintpaulia ionantha[23]. Therefore, we used the ITS 1 sequence of Saintpaulia ionantha to estimate the position of cv. “Iceberg” in the phylogenetic trees.
Munetaka Hosokawa - One of the best experts on this subject based on the ideXlab platform.
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African violet (Saintpaulia ionantha H. Wendl.): classical breeding and progress in the application of biotechnological techniques
Folia Horticulturae, 2017Co-Authors: Jaime A. Teixeira Da Silva, Yaser Hassan Dewir, Adhityo Wicaksono, Haenghoon Kim, Songjun Zeng, Leela Sahijram, Stephen F. Chandler, Munetaka HosokawaAbstract:As a result of its domestication, breeding and subsequent commercialization, African violet (Saintpaulia ionantha H. Wendl.) has become the most famous and popular Saintpaulia species. There is interest in producing cultivars that have increased resistance to pests and low temperature, in the introduction of novel horticultural characteristics such as leaf shape, flower colour, size and form, and in improved productivity and enhanced flower duration in planta. In African violet, techniques such as the application of chemical mutagens (ethylmethanesulfonate, N-nitroso-N-methylurea), radiation (gamma (γ)-rays, X-rays, carbon ion beams) and colchicine have been successfully applied to induce mutants. Among these techniques, γ radiation and colchicine have been the most commonly applied mutagens. This review offers a short synthesis of the advances made in African violet breeding, including studies on mutation and somaclonal variation caused by physical and chemical factors, as well as transgenic strategies using Agrobacterium-mediated transformation and particle bombardment. In African violet, Agrobacterium-mediated transformation is affected by the Agrobacterium strain, selection marker, and cutting-induced wounding stress. Somaclonal variation, which arises in tissue cultures, can be problematic in maintaining true-to-type clonal material, but may be a useful tool for obtaining variation in flower colour. The only transgenic African violet plants generated to date with horticulturally useful traits are tolerant to boron (heavy metal) stress, or bear a glucanase-chitinase gene.
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The histological study in sympetalous corolla development of pinwheel-type flowers of Saintpaulia
Scientia Horticulturae, 2017Co-Authors: Soo-jung Yang, Sho Ohno, Ayumi Deguchi, Mitsuru Sato, Mariko Goto, Motoaki Doi, Miki Ohnishi, Fumi Tatsuzawa, Munetaka HosokawaAbstract:Abstract In this study, we revealed how the petals of Saintpaulia fuse into a corolla by using pinwheel phenotype cultivars. Striped patterns in petal, called pinwheel in Saintpaulia, are attractive phenotypes and thought to be the result of periclinal chimerism. For the selection of a genuine periclinal chimeric cultivar from three pinwheel cultivars, adventitious shoots were induced from leaf lamina. Shoot regeneration was observed from the epidermis in all cultivars by microscopic observation. All regenerated shoots from ‘Kaname’ flowered as monochromatic pink flowers, corresponding to an L1 phenotype of the cultivar. From the other two cultivars, many shoots flowered not only as an epidermal phenotype but also as a phenotype of the inner layer. In addition, shoot regeneration was induced from epidermis-peeled petioles from these three cultivars. All shoots from ‘Kaname’ flowered as monochromatic blue flowers, corresponding to an L2 phenotype. On the other hand, many shoots from ‘Kilauea’ flowered not only as monochromatic flowers, corresponding to an L2 phenotype, but also as bi-colored flowers. ‘Innocent Pink’ did not produce shoots from epidermal-peeled petioles. These results suggested that ‘Kaname’ is a genuine periclinal chimera, while the other two cultivars have other mechanisms for pinwheel expression. Genomic PCR using primers that amplifies almost the full length of flavonoid 3′,5′-hydroxylase (F3ʹ5ʹH) revealed the gene to be non-functional in pink flowers from L1 of ‘Kaname’. From monochromatic pink plants and pink portions of the corolla of ‘Kaname’, full-length F3ʹ5ʹH was not amplified. Similar results were obtained by quantitative PCR. Finally, we observed the fused portion of the petals and revealed that the petal fusion did not occur by postgenital fusion but by “connection”. The process, in Saintpaulia, comprises periclinal cell division in L1 during petal development, active cell division at the edge of the petal, adhesion to the next petals, and fusion. These steps create a striped flower color in Saintpaulia.
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MORPHOGENESIS AND DEVELOPMENTAL BIOLOGY OF AFRICAN VIOLET (Saintpaulia IONANTHA H. WENDL.)
Alexandru Ioan Cuza University of Iasi, 2016Co-Authors: Jaime Teixeira A. Da Silva, Yaser Hassan Dewir, Adhityo Wicaksono, Mafatlal M. Kher, Haenghoon Kim, Munetaka Hosokawa, Songjun ZengAbstract:African violet (Saintpaulia ionantha H. Wendl.) has been domesticated, bred and commercialized. It is the most famous and popular of the Saintpaulia species, its ornamental value arising from its attractive leaves and flowers. African violet plants are easy to propagate by adventitious organ regeneration and are very sensitive to environmental factors including light, temperature, humidity, CO2 concentration and photoperiod. This review offers a short synthesis on advances made in conventional vegetative propagation by adventitious organ regeneration, select early historical in vitro developmental perspectives, and vegetative and reproductive development of African violet
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Three acylated anthocyanins and a flavone glycoside in violet-blue flowers of Saintpaulia ‘Thamires’
South African Journal of Botany, 2012Co-Authors: Fumi Tatsuzawa, Munetaka Hosokawa, Norio Saito, T. HondaAbstract:Abstract Three new acylated anthocyanidin 3-rutinoside-5-glucosides were isolated from the violet-blue flowers of Saintpaulia ‘Thamires’ ( Saintpaulia sp.) along with a known flavone glycoside. Three new acetylated anthocyanins were determined to be 3- O -[6- O -(4- O -(acetyl)-α-rhamnopyranosyl)-β-glucopyranoside]-5- O -(β-glucopyranoside)s of malvidin (pigment 1), peonidin (pigment 2), and pelargonidin (pigment 3) by chemical and spectroscopic methods. HPLC analysis revealed that malvidin 3- O -acetylrutinoside-5- O -glucoside existed as a dominant pigment in the violet-blue flowers. Moreover, the isolated flavone was identified to be apigenin 4′- O -β-glucuronopyranoside (pigment 4). On the visible absorption spectral curves of fresh violet-blue petals and in their crude extracts in pH 5.0 buffer solution, two characteristic absorption maxima at 547 and 577 nm, with a shoulder near 620 nm, were observed. In contrast, the absorption curves of malvidin 3- O -acetylrutinoside-5- O -glucoside and its deacyl anthocyanin exhibited only one maximum at 535 nm in pH 5.0 buffer solution, and its color was violet and soon fell into decay. However, by addition of apigenin 4′- O -glucuronide, the color of malvidin 3- O -acetylrutinoside-5- O -glucoside changed from violet to violet-blue, similar to that of the fresh flower in pH 5.0 buffer solution. The absorption curve of its violet-blue solution exhibited two similar absorption maxima at 547 and 577 nm, with a shoulder near 620 nm. These results suggest that intermolecular copigmentation between malvidin 3- O -acetylrutinoside-5- O -glucoside and apigenin 4′- O -glucuronide may be responsible for the violet-blue flower color of S . ‘Thamires’.
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Somaclonal Variation Is Induced De Novo via the Tissue Culture Process: A Study Quantifying Mutated Cells in Saintpaulia
PloS one, 2011Co-Authors: Mitsuru Sato, Munetaka Hosokawa, Motoaki DoiAbstract:Background The origin of somaclonal variation has not been questioned previously, i.e., “pre-existing mutations” in explants and “newly induced mutations” arising from the tissue culture process have not been distinguished. This is primarily because there has been no reliable molecular method for estimating or quantifying variation. Methodology/Principal Findings We adopted a petal-variegated cultivar of Saintpaulia ‘Thamires’ (Saintpaulia sp.) as the model plant. Based on the difference between the pre- and post-transposon excision sequence of the promoter region of flavonoid 3′, 5′-hydoroxylase (F3′5′H), we estimated mutated (transposon-excised) cell percentages using a quantitative real-time PCR. Mutated cell percentages in leaf laminae used as explants was 4.6 and 2.4% in highly or low variegation flower plants, respectively, although the occurrences of blue color mutants in their regenerants were more than 40%. Preexisting mutated cell percentages in cultured explants were considerably lower than the mutated plant percentage among total regenerants via tissue culture. Conclusions/Significance The estimation of mutated cell percentages became possible using the quantitative real-time PCR. The origins of mutations were successfully distinguished; it was confirmed that somaclonal variations are mainly caused by newly generated mutations arising from tissue culture process.
