The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ruth C. Martin - One of the best experts on this subject based on the ideXlab platform.
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transcriptome analysis of Lolium temulentum exposed to a combination of drought and heat stress
Plants, 2021Co-Authors: Ruth C. Martin, Brent Kronmiller, James E DombrowskiAbstract:Drought and heat are two major stresses predicted to increase in the future due to climate change. Plants exposed to multiple stressors elicit unique responses from those observed under individual stresses. A comparative transcriptome analysis of Lolium temulentum exposed to drought plus heat and non-stressed control plants revealed 20,221 unique up-regulated and 17,034 unique down-regulated differentially regulated transcripts. Gene ontology analysis revealed a strong emphasis on transcriptional regulation, protein folding, cell cycle/parts, organelles, binding, transport, signaling, oxidoreductase, and antioxidant activity. Differentially expressed genes (DEGs) encoding for transcriptional control proteins such as basic leucine zipper, APETALA2/Ethylene Responsive Factor, NAC, and WRKY transcription factors, and Zinc Finger (CCCH type and others) proteins were more often up-regulated, while DEGs encoding Basic Helix-Loop-Helix, MYB and GATA transcription factors, and C2H2 type Zinc Finger proteins were more often down-regulated. The DEGs encoding heat shock transcription factors were only up-regulated. Of the hormones, auxin-related DEGs were the most prevalent, encoding for auxin response factors, binding proteins, and efflux/influx carriers. Gibberellin-, cytokinin- and ABA-related DEGs were also prevalent, with fewer DEGs related to jasmonates and brassinosteroids. Knowledge of genes/pathways that grasses use to respond to the combination of heat/drought will be useful in developing multi-stress resistant grasses.
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transcriptome analysis of wounding in the model grass Lolium temulentum
Plants (Basel Switzerland), 2020Co-Authors: James E Dombrowski, Brent Kronmiller, Vicky G Hollenbeck, Ruth C. MartinAbstract:For forage and turf grasses, wounding is a predominant stress that often results in extensive loss of vegetative tissues followed by rapid regrowth. Currently, little is known concerning the perception, signaling, or molecular responses associated with wound stress in forage- and turf-related grasses. A transcriptome analysis of Lolium temulentum plants subjected to severe wounding revealed 9413 upregulated and 7704 downregulated, distinct, differentially expressed genes (DEGs). Categories related to signaling, transcription, and response to stimuli were enriched in the upregulated DEGs. Specifically, sequences annotated as enzymes involved in hormone biosynthesis/action and cell wall modifications, mitogen-activated protein kinases, WRKY transcription factors, proteinase inhibitors, and pathogen defense-related DEGs were identified. Surprisingly, DEGs related to heat shock and chaperones were more prevalent in the downregulated DEGs when compared with the upregulated DEGs. This wound transcriptome analysis is the first step in identifying the molecular components and pathways used by grasses in response to wounding. The information gained from the analysis will provide a valuable molecular resource that will be used to develop approaches that can improve the recovery, regrowth, and long-term fitness of forage and turf grasses before/after cutting or grazing.
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transcriptome analysis of the model grass Lolium temulentum exposed to green leaf volatiles
BMC Plant Biology, 2019Co-Authors: James E Dombrowski, Brent Kronmiller, Adelaide C Rhodes, John A Henning, Vicky G Hollenbeck, Ruth C. MartinAbstract:Forage and turf grasses are routinely cut and grazed upon throughout their lifecycle. When grasses are cut or damaged, they rapidly release a volatile chemical cocktail called green leaf volatiles (GLV). Previously we have shown that mechanical wounding or exposure to GLV released from cut grass, activated a Lt 46 kDa mitogen-activated protein kinase (MAPK) within 3 min and a 44 kDa MAPK within 15–20 min in the model grass species Lolium temulentum (Lt). Currently very little is known concerning the perception, signaling or molecular responses associated with wound stress in grasses. Since GLV are released during wounding, we wanted to investigate what genes and signaling pathways would be induced in undamaged plants exposed to GLV. RNA-Seq generated transcriptome of Lolium plants exposed to GLV identified 4308 up- and 2794 down-regulated distinct differentially-expressed sequences (DES). Gene Ontology analysis revealed a strong emphasis on signaling, response to stimulus and stress related categories. Transcription factors and kinases comprise over 13% of the total DES found in the up-regulated dataset. The analysis showed a strong initial burst within the first hour of GLV exposure with over 60% of the up-regulated DES being induced. Specifically sequences annotated for enzymes involved in the biosynthesis of jasmonic acid and other plant hormones, mitogen-activated protein kinases and WRKY transcription factors were identified. Interestingly, eleven DES for ferric reductase oxidase, an enzyme involved in iron uptake and transport, were exclusively found in the down-regulated dataset. Twelve DES of interest were selected for qRT-PCR analysis; all displayed a rapid induction one hour after GLV exposure and were also strongly induced by mechanical wounding. The information gained from the analysis of this transcriptome and previous studies suggests that GLV released from cut grasses transiently primes an undamaged plant’s wound stress pathways for potential oncoming damage, and may have a dual role for inter- as well as intra-plant signaling.
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transcriptome analysis of the model grass Lolium temulentum exposed to green leaf volatiles
BMC Plant Biology, 2019Co-Authors: James E Dombrowski, Brent Kronmiller, Adelaide C Rhodes, John A Henning, Vicky G Hollenbeck, Ruth C. MartinAbstract:Forage and turf grasses are routinely cut and grazed upon throughout their lifecycle. When grasses are cut or damaged, they rapidly release a volatile chemical cocktail called green leaf volatiles (GLV). Previously we have shown that mechanical wounding or exposure to GLV released from cut grass, activated a Lt 46 kDa mitogen-activated protein kinase (MAPK) within 3 min and a 44 kDa MAPK within 15–20 min in the model grass species Lolium temulentum (Lt). Currently very little is known concerning the perception, signaling or molecular responses associated with wound stress in grasses. Since GLV are released during wounding, we wanted to investigate what genes and signaling pathways would be induced in undamaged plants exposed to GLV. RNA-Seq generated transcriptome of Lolium plants exposed to GLV identified 4308 up- and 2794 down-regulated distinct differentially-expressed sequences (DES). Gene Ontology analysis revealed a strong emphasis on signaling, response to stimulus and stress related categories. Transcription factors and kinases comprise over 13% of the total DES found in the up-regulated dataset. The analysis showed a strong initial burst within the first hour of GLV exposure with over 60% of the up-regulated DES being induced. Specifically sequences annotated for enzymes involved in the biosynthesis of jasmonic acid and other plant hormones, mitogen-activated protein kinases and WRKY transcription factors were identified. Interestingly, eleven DES for ferric reductase oxidase, an enzyme involved in iron uptake and transport, were exclusively found in the down-regulated dataset. Twelve DES of interest were selected for qRT-PCR analysis; all displayed a rapid induction one hour after GLV exposure and were also strongly induced by mechanical wounding. The information gained from the analysis of this transcriptome and previous studies suggests that GLV released from cut grasses transiently primes an undamaged plant’s wound stress pathways for potential oncoming damage, and may have a dual role for inter- as well as intra-plant signaling.
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green leaf volatiles fire and nonanoic acid activate mapkinases in the model grass species Lolium temulentum
BMC Research Notes, 2014Co-Authors: James E Dombrowski, Ruth C. MartinAbstract:Previously it has been shown that mechanical wounding, salinity and heat activated a 46 kDa and 44 kDa mitogen-activated protein kinases (MAPKs) in forage related grasses. Forage and turf related grasses are utilized in diverse environments where they are routinely subjected to herbicides and exposed to fire and volatiles after cutting, however very little is known concerning the perception or molecular responses to these different stresses or compounds. In the model grass species Lolium temulentum (Lt), a 46 kDa mitogen-activated protein kinase (MAPK) was activated in the leaves within 5 min and a 44 kDa MAPK 15 min after exposure to green leaf volatiles released from grass clippings. When the tips of leaves of Lt plants were scorched by fire, the 46 kDa MAPK and 44 kDa MAPK were rapidly activated within 5 min and 20 min respectively in the treated leaf, and 15 min systemically in an adjacent untreated tiller after exposure to fire. Nonanoic acid (pelargonic acid), a component in herbicides used on grasses, activated a 46 kDa MAPK in the treated leaves within 5 min of exposure and 15 min in systemic tissues. At concentrations normally used in the herbicides, nonanoic acid was found to only weakly activate the 44 kDa MAPK after an hour in treated leaves, but strongly activated it in the systemic tillers 30 min after treatment. Acetic acid, HCl and NaOH also were found to activate these MAPKs in treated tillers. The rapid activation of these MAPKs to a wide range of stress stimuli, suggest that these MAPKs play a role in the perception and response to these stresses and compounds. The activation of the MAPK by green leaf volatiles indicates a role for these compounds in wound signaling in grasses.
James E Dombrowski - One of the best experts on this subject based on the ideXlab platform.
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transcriptome analysis of Lolium temulentum exposed to a combination of drought and heat stress
Plants, 2021Co-Authors: Ruth C. Martin, Brent Kronmiller, James E DombrowskiAbstract:Drought and heat are two major stresses predicted to increase in the future due to climate change. Plants exposed to multiple stressors elicit unique responses from those observed under individual stresses. A comparative transcriptome analysis of Lolium temulentum exposed to drought plus heat and non-stressed control plants revealed 20,221 unique up-regulated and 17,034 unique down-regulated differentially regulated transcripts. Gene ontology analysis revealed a strong emphasis on transcriptional regulation, protein folding, cell cycle/parts, organelles, binding, transport, signaling, oxidoreductase, and antioxidant activity. Differentially expressed genes (DEGs) encoding for transcriptional control proteins such as basic leucine zipper, APETALA2/Ethylene Responsive Factor, NAC, and WRKY transcription factors, and Zinc Finger (CCCH type and others) proteins were more often up-regulated, while DEGs encoding Basic Helix-Loop-Helix, MYB and GATA transcription factors, and C2H2 type Zinc Finger proteins were more often down-regulated. The DEGs encoding heat shock transcription factors were only up-regulated. Of the hormones, auxin-related DEGs were the most prevalent, encoding for auxin response factors, binding proteins, and efflux/influx carriers. Gibberellin-, cytokinin- and ABA-related DEGs were also prevalent, with fewer DEGs related to jasmonates and brassinosteroids. Knowledge of genes/pathways that grasses use to respond to the combination of heat/drought will be useful in developing multi-stress resistant grasses.
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transcriptome analysis of wounding in the model grass Lolium temulentum
Plants (Basel Switzerland), 2020Co-Authors: James E Dombrowski, Brent Kronmiller, Vicky G Hollenbeck, Ruth C. MartinAbstract:For forage and turf grasses, wounding is a predominant stress that often results in extensive loss of vegetative tissues followed by rapid regrowth. Currently, little is known concerning the perception, signaling, or molecular responses associated with wound stress in forage- and turf-related grasses. A transcriptome analysis of Lolium temulentum plants subjected to severe wounding revealed 9413 upregulated and 7704 downregulated, distinct, differentially expressed genes (DEGs). Categories related to signaling, transcription, and response to stimuli were enriched in the upregulated DEGs. Specifically, sequences annotated as enzymes involved in hormone biosynthesis/action and cell wall modifications, mitogen-activated protein kinases, WRKY transcription factors, proteinase inhibitors, and pathogen defense-related DEGs were identified. Surprisingly, DEGs related to heat shock and chaperones were more prevalent in the downregulated DEGs when compared with the upregulated DEGs. This wound transcriptome analysis is the first step in identifying the molecular components and pathways used by grasses in response to wounding. The information gained from the analysis will provide a valuable molecular resource that will be used to develop approaches that can improve the recovery, regrowth, and long-term fitness of forage and turf grasses before/after cutting or grazing.
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transcriptome analysis of the model grass Lolium temulentum exposed to green leaf volatiles
BMC Plant Biology, 2019Co-Authors: James E Dombrowski, Brent Kronmiller, Adelaide C Rhodes, John A Henning, Vicky G Hollenbeck, Ruth C. MartinAbstract:Forage and turf grasses are routinely cut and grazed upon throughout their lifecycle. When grasses are cut or damaged, they rapidly release a volatile chemical cocktail called green leaf volatiles (GLV). Previously we have shown that mechanical wounding or exposure to GLV released from cut grass, activated a Lt 46 kDa mitogen-activated protein kinase (MAPK) within 3 min and a 44 kDa MAPK within 15–20 min in the model grass species Lolium temulentum (Lt). Currently very little is known concerning the perception, signaling or molecular responses associated with wound stress in grasses. Since GLV are released during wounding, we wanted to investigate what genes and signaling pathways would be induced in undamaged plants exposed to GLV. RNA-Seq generated transcriptome of Lolium plants exposed to GLV identified 4308 up- and 2794 down-regulated distinct differentially-expressed sequences (DES). Gene Ontology analysis revealed a strong emphasis on signaling, response to stimulus and stress related categories. Transcription factors and kinases comprise over 13% of the total DES found in the up-regulated dataset. The analysis showed a strong initial burst within the first hour of GLV exposure with over 60% of the up-regulated DES being induced. Specifically sequences annotated for enzymes involved in the biosynthesis of jasmonic acid and other plant hormones, mitogen-activated protein kinases and WRKY transcription factors were identified. Interestingly, eleven DES for ferric reductase oxidase, an enzyme involved in iron uptake and transport, were exclusively found in the down-regulated dataset. Twelve DES of interest were selected for qRT-PCR analysis; all displayed a rapid induction one hour after GLV exposure and were also strongly induced by mechanical wounding. The information gained from the analysis of this transcriptome and previous studies suggests that GLV released from cut grasses transiently primes an undamaged plant’s wound stress pathways for potential oncoming damage, and may have a dual role for inter- as well as intra-plant signaling.
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transcriptome analysis of the model grass Lolium temulentum exposed to green leaf volatiles
BMC Plant Biology, 2019Co-Authors: James E Dombrowski, Brent Kronmiller, Adelaide C Rhodes, John A Henning, Vicky G Hollenbeck, Ruth C. MartinAbstract:Forage and turf grasses are routinely cut and grazed upon throughout their lifecycle. When grasses are cut or damaged, they rapidly release a volatile chemical cocktail called green leaf volatiles (GLV). Previously we have shown that mechanical wounding or exposure to GLV released from cut grass, activated a Lt 46 kDa mitogen-activated protein kinase (MAPK) within 3 min and a 44 kDa MAPK within 15–20 min in the model grass species Lolium temulentum (Lt). Currently very little is known concerning the perception, signaling or molecular responses associated with wound stress in grasses. Since GLV are released during wounding, we wanted to investigate what genes and signaling pathways would be induced in undamaged plants exposed to GLV. RNA-Seq generated transcriptome of Lolium plants exposed to GLV identified 4308 up- and 2794 down-regulated distinct differentially-expressed sequences (DES). Gene Ontology analysis revealed a strong emphasis on signaling, response to stimulus and stress related categories. Transcription factors and kinases comprise over 13% of the total DES found in the up-regulated dataset. The analysis showed a strong initial burst within the first hour of GLV exposure with over 60% of the up-regulated DES being induced. Specifically sequences annotated for enzymes involved in the biosynthesis of jasmonic acid and other plant hormones, mitogen-activated protein kinases and WRKY transcription factors were identified. Interestingly, eleven DES for ferric reductase oxidase, an enzyme involved in iron uptake and transport, were exclusively found in the down-regulated dataset. Twelve DES of interest were selected for qRT-PCR analysis; all displayed a rapid induction one hour after GLV exposure and were also strongly induced by mechanical wounding. The information gained from the analysis of this transcriptome and previous studies suggests that GLV released from cut grasses transiently primes an undamaged plant’s wound stress pathways for potential oncoming damage, and may have a dual role for inter- as well as intra-plant signaling.
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green leaf volatiles fire and nonanoic acid activate mapkinases in the model grass species Lolium temulentum
BMC Research Notes, 2014Co-Authors: James E Dombrowski, Ruth C. MartinAbstract:Previously it has been shown that mechanical wounding, salinity and heat activated a 46 kDa and 44 kDa mitogen-activated protein kinases (MAPKs) in forage related grasses. Forage and turf related grasses are utilized in diverse environments where they are routinely subjected to herbicides and exposed to fire and volatiles after cutting, however very little is known concerning the perception or molecular responses to these different stresses or compounds. In the model grass species Lolium temulentum (Lt), a 46 kDa mitogen-activated protein kinase (MAPK) was activated in the leaves within 5 min and a 44 kDa MAPK 15 min after exposure to green leaf volatiles released from grass clippings. When the tips of leaves of Lt plants were scorched by fire, the 46 kDa MAPK and 44 kDa MAPK were rapidly activated within 5 min and 20 min respectively in the treated leaf, and 15 min systemically in an adjacent untreated tiller after exposure to fire. Nonanoic acid (pelargonic acid), a component in herbicides used on grasses, activated a 46 kDa MAPK in the treated leaves within 5 min of exposure and 15 min in systemic tissues. At concentrations normally used in the herbicides, nonanoic acid was found to only weakly activate the 44 kDa MAPK after an hour in treated leaves, but strongly activated it in the systemic tillers 30 min after treatment. Acetic acid, HCl and NaOH also were found to activate these MAPKs in treated tillers. The rapid activation of these MAPKs to a wide range of stress stimuli, suggest that these MAPKs play a role in the perception and response to these stresses and compounds. The activation of the MAPK by green leaf volatiles indicates a role for these compounds in wound signaling in grasses.
C J Pollock - One of the best experts on this subject based on the ideXlab platform.
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the kinetic analysis of fructan biosynthesis in excised leaves of Lolium temulentum l
New Phytologist, 2006Co-Authors: Ian M. Sims, R Morgan, C J PollockAbstract:SUMMARY Excised leaves of Lolium temulentum L. were fed `3C02 at 99 % isotopic abundance in order to study the kinetics of incorporation of photosynthetically fixed carbon into different fructans and to determine the pathways of synthesis between sucrose and high-molecular-weight fructan. Following 6 h exposure to `3C02 of detached and illuminated leaves, analysis of the accumulation of 1-kestose, 6-kestose and neokestose, and of the pattern of labelling observed in these isomers, suggested that they were each formed directly from sucrose at different rates. Similarly, the data suggested that the tetrasaccharide isomers were formed directly from their trisaccharide precursors. Changes in the concentration of '3C both in the total water-soluble component of the leaves and the fructan pool after 20 h exposure to `3C02 suggested that there was a continual turnover of fructosyl residues. The formation of trisaccharides from sucrose and subsequent fructosyl transfer to oligo- and polysaccharides of progressively higher molecular weight was consistent with a direct precursor-product relationship. The stable concentration of sucrose observed in leaves between 14 h and 48 h after excision indicated that fructan metabolism in L. temulentum may serve to regulate the sucrose content of the tissue.
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cloning and characterization of a putative fructosyltransferase and two putative invertase genes from the temperate grass Lolium temulentum l
Journal of Experimental Botany, 2004Co-Authors: J Gallagher, Andrew J. Cairns, C J PollockAbstract:The invertases of Lolium temulentum have been characterized at the enzyme level. However, studies on the expression of the genes coding for these enzymes have been lacking. To elucidate the role of acid 'invertase-like' genes in sucrose metabolism and carbon partitioning in Gramineae further, three 'invertase-like' homologous clones were isolated from L. temulentum cDNA expression libraries based on leaf tissue, using maize soluble invertase probes. The effect of developmental stage and alterations in carbohydrate status on the expression and tissue distribution of these genes was investigated. The three highly homologous genes (Inv 1:2, Inv 1:4, and FT 2:2) show different patterns of expression and different tissue distribution. Inv 1:2 was predominantly expressed in root tissue. Expression increased during the dark in root and tiller base tissue. Minimal variations in gene expression were observed in leaf tissue following changes in carbohydrate status. Inv 1:4 was predominantly expressed in tiller bases, leaf sheath, and leaf base, with increased expression in tissue samples in the dark period. FT 2:2 was also predominantly expressed in tiller bases, leaf sheath, and leaf base. Higher expression was observed in leaf tissue following increases in carbohydrate content, in a manner that paralleled the regulation and spatial occurrence of fructan in the leaf tissue. Whilst invertases and fructosyltransferases are difficult to distinguish at the level of the whole sequence, analysis of 5' sequence and specific amino acids allows discrimination which correlates with patterns of expression within the tissue. Based on expression patterns and sequence characteristics, it is proposed that Inv 1:2 and Inv 1:4 code for soluble acid invertases, whilst FT 2:2 codes for a fructosyltransferase.
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purification and characterization of invertases from leaves of Lolium temulentum
New Phytologist, 1997Co-Authors: R P Walker, Ana L. Winters, C J PollockAbstract:SUMMARY Leaves of Lolium temulentum L. contain both low and high pI acid invertases. Immunoblot analysis of a highly purified preparation of these forms suggested that they both possess a subunit molecular weight of 68 kDa. Protoplasts and their derived vacuoles were isolated from leaf blades and contained sufficient acid invertase activity to account for all the activity found in the soluble fraction of crude homogenates of leaf blades. Alkaline invertase was present in the basal region of leaves and, unlike acid invertase, did not bind to Con A-Sepharose, suggesting that the acid invertase was a glycoprotein and that the alkaline invertase was not. Fructose inhibited both acid and alkaline invertases. The hypothesis is discussed that activity in vivo could be modulated by the concentration of free fructose.
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fructan exohydrolase activity in leaves of Lolium temulentum l
New Phytologist, 1991Co-Authors: Richard J Simpson, R P Walker, C J PollockAbstract:summary Crude extracts from leaves of Lolium temulentum L. exhibited invertase activity and activity capable of releasing fructost from fructans (fructan exohydrolase; FEH), The optimum pH for FEH activity was between pH 4.8 and 5.5. When shoots of 10-d-old seedlings were induced to accumulate fructans by cooling their roots to 5 °C and exposing them to continuous light, FEH activity declined by at least 50 %, FEH activity increased when the shoots were induced to mobilize the fructans by warming the roots to the ambient temperature (20°C) and darkening the plants. Declining activity coincided with loss of one of at least two FEH isoforms observed after starch gel electrophoresis. Partially purified FEH from leaves of L. temulentum was inhibited when assayed in the presence of 10 HIM sucrose.
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the control of sucrose synthesis in leaves of Lolium temulentum l a fructan accumulating grass
New Phytologist, 1991Co-Authors: B E Collis, C J PollockAbstract:summary The control of sucrose synthesis was studied in leaves of the fructan-accumulating species Lolium temulentum L. The cytoplasm it fructose-1,6-bisphosphatase (Cyt'F-1,6-BPase) was partially purified and its kinetic properties compared with the reported values for the enzyme from spinach leaves. The enzymes from the two species were similar, particularly in their inhibition by fructose-2,6-bisphosphate (F-2,6BP). Leaves were excised and illuminated or whole plants were chilled and illuminated in order to increase the accumulation of sucrose and low-molecular-weight fructan, Leaf glucose-6-phosphate (G-6-P) and fructose-6-phosphate (F-6-P) contents were estimated. The G-6-P/F-6-P ratio showed that most of the hexose phosphates were present in the cytoplasm. In excised leaves G-6-P concentrations were higher than controls after 4 h of illumination, probably reflecting the release of glucose by fructan synthesis. This extra source of substrate supply may disrupt the coordinated control of sucrose phosphate synthase (SPS) and Cyt'F-1,6-BPase. The calculated activity of Cyt'F-1,6-BPase in vivo is insufficient to catalyse the observed flux of photo assimilates to sucrose and fructan. The maximum catalytic activity of phosphofructophosphotransferase (PFP) was determined, and was found to be 12–14Umol hexose g1 f. wt h1 in control leaves. It is proposed that, given suitable metabolite concentrations, PFP could supplement the inhibited Cyt'F-1,6-BPase activity and contribute to the flux of photo assimilates to sucrose and fructan.
Georges Bernier - One of the best experts on this subject based on the ideXlab platform.
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darkness promotes flowering in the absolute long day requiring plant Lolium temulentum l ceres
Journal of Experimental Botany, 1997Co-Authors: Claire Perilleux, Georges Bernier, Jeanmarie KinetAbstract:Vegetative plants of the long-day grass Lolium temulentum L. Ceres were exposed to threshold long days or light breaks. Protracted darkness given just afterwards clearly promoted flowering and was weakly inductive on its own. The promotive effect of darkness was restricted to floral induction since further apical development was weak.
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leaf carbohydrate status in Lolium temulentum during the induction of flowering
New Phytologist, 1997Co-Authors: Claire Perilleux, Georges BernierAbstract:SUMMARY Unifoliated plants of Lolium temulentum L. ev. Ceres, a qualitative long-day grass, were induced to flower by one 24-h long day (LD) or by one 8-h short day (SD) advanced by 1 2 h in the normal regime, so-called ‘displaced short day’ (DSD). Standard light for SD and DSD was a mixture of fluorescence and incandescence at 400 μmol m−2 s−1whereas the extension period of the 24-h LD was solely incandescence at 10–15 μmol m−2 s−1. The DSD system was first characterized by the timings of floral induction, stimulus translocation and apical development. Carbohydrates in the blade tissues and in leaf exudate were analysed comparatively in vegetative and induced plants. Fructans were not detected in the leaf tissues whereas sucrose and starch were found to be present in similar amounts. In SD, their contents exhibited a diurnal fluctuation and were not in large excess. The common change observed during the two inductive treatments was that starch remained at a high level during the LD extension, even though the lighting was unsuitable for photosynthesis, and increased transiently in DSD. Sucrose was the major sugar contained in the leaf exudate. Its content increased when flowering was induced, but not at the same time in the two systems. In LD, sucrose exudation rose when plants were returned to standard light after the inductive cycle, i.e. after the LD stimulus had left the leaf blade. By contrast, during the DSD, sucrose was transported at the same time as the floral stimulus. Results are discussed together with the methods used to time stimulus translocation and their implications.
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circadian rhythms and the induction of flowering in the long day grass Lolium temulentum l
Plant Cell and Environment, 1994Co-Authors: Claire Perilleux, Georges Bernier, Jeanmarie KinetAbstract:Plants of Lolium temulentum L. strain Ceres were grown in 8-h short day (SD) for 45 d before being exposed either to a single long day (LD) or to a single 8-h SD given during an extended dark period. For LD induction, the critical photoperiod was between 12 and 14 h, and more than 16 h were needed for a maximal flowering response. During exposure to a single 24-h LD, the translocation of the floral stimulus began between the fourteenth and the sixteenth hours after the start of the light period, and was completed by the twenty-fourth hour. Full flowering was also induced by one 8-h SD beginning 4 or 28 h after the start of a 40-h dark period, i.e. by shifting 12 h forward or beyond the usual SD. The effectiveness of a so-called 'displaced short day' (DSD) was not affected by light quality and light intensity. With a mixture of incandescent and fluorescent lights at a total photosynthetic photon flux density of 400 mu mol m(-2) s(-1), a 4-h light exposure beginning 4 h after the start of a 40-h dark period was sufficient to induce 100% flowering. The flower-inducing effect of a single 8-h DSD was also assessed during a 64-h dark period. Results revealed two maxima at a 20-h interval. This fluctuation in light sensitivity suggests that a circadian rhythm is involved in the control of flowering of L. temulentum.
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early increase in the mitotic index in the shoot apex of Lolium temulentum cv ceres during the floral transition
Journal of Experimental Botany, 1993Co-Authors: Annie Jacqmard, J Bomans, J C Ormrod, Georges BernierAbstract:Six-week-old Lolium temulentum cv. Ceres plants were induced to flower by a single long day (Day 1). Cell proliferation was analysed in the apex during the period extending from Day 1 to Day 3. A stimulation of mitotic and DNA synthetic activities was observed in the apical summit at 8 h of the photoextension period of the LD, i.e. before any apparent movement of the floral stimulus out of the leaves and well in advance of apex evocation.
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reproductive development in Lolium temulentum l spike morphogenesis and grain set limitations
Journal of Experimental Botany, 1991Co-Authors: Claire Perilleux, Georges Bernier, Jeanmarie KinetAbstract:Reproductive development in cereals is not easy to investigate because their quantitative response to environmental factors makes it difficult to synchronize the plants. In this paper, one of our aims was to assess whether Lolium temulentum strain Ceres, a qualitative long-day grass, could serve as a model of reproductive development for cereals. The morphological patterns from floral transition to seed set were studied. A flowering scale was established to evaluate developmental rate during spike morphogenesis. Apex growth was found to increase according to biphasic kinetics; double ridge appearance marked the beginning of an exponential phase. Developmental progression and apical growth rate were both increased by giving repeated long days. In contrast, the final number of lateral spikelets (20-25) could not be manipulated after the beginning of long-day treatment. When plants were kept in continuous light from the beginning of induction, double ridges appeared on the fifth 24 h cycle. Spikelet initiation began in the upper mid-part of the spike, and then extended aeroand basipetally. The phase of spikelet initiation lasted 6 d, with 1-5 to 1-9 spikelets being produced daily. Within each spikelet, florets were initiated at an average rate of 1-3 primordia per day and developed acropetally. The first signs of apical site degeneration were observed in the most developed upper spikelets just before heading. Ear emergence occurred between the 20th and 25th cycles of continuous light; anthesis was observed 6 or 7 d later. The proportion of florets setting grain averaged about 40%. Grains were produced mainly in the lower spikelets while the upper mid-part of the inflorescence showed a much lower fertility rate. Complex developmental gradients described in this paper suggest that L. temulentum could serve as a model of reproductive development in cereals, with the added advantage of flowering in response to a single long-day.
Claire Perilleux - One of the best experts on this subject based on the ideXlab platform.
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darkness promotes flowering in the absolute long day requiring plant Lolium temulentum l ceres
Journal of Experimental Botany, 1997Co-Authors: Claire Perilleux, Georges Bernier, Jeanmarie KinetAbstract:Vegetative plants of the long-day grass Lolium temulentum L. Ceres were exposed to threshold long days or light breaks. Protracted darkness given just afterwards clearly promoted flowering and was weakly inductive on its own. The promotive effect of darkness was restricted to floral induction since further apical development was weak.
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leaf carbohydrate status in Lolium temulentum during the induction of flowering
New Phytologist, 1997Co-Authors: Claire Perilleux, Georges BernierAbstract:SUMMARY Unifoliated plants of Lolium temulentum L. ev. Ceres, a qualitative long-day grass, were induced to flower by one 24-h long day (LD) or by one 8-h short day (SD) advanced by 1 2 h in the normal regime, so-called ‘displaced short day’ (DSD). Standard light for SD and DSD was a mixture of fluorescence and incandescence at 400 μmol m−2 s−1whereas the extension period of the 24-h LD was solely incandescence at 10–15 μmol m−2 s−1. The DSD system was first characterized by the timings of floral induction, stimulus translocation and apical development. Carbohydrates in the blade tissues and in leaf exudate were analysed comparatively in vegetative and induced plants. Fructans were not detected in the leaf tissues whereas sucrose and starch were found to be present in similar amounts. In SD, their contents exhibited a diurnal fluctuation and were not in large excess. The common change observed during the two inductive treatments was that starch remained at a high level during the LD extension, even though the lighting was unsuitable for photosynthesis, and increased transiently in DSD. Sucrose was the major sugar contained in the leaf exudate. Its content increased when flowering was induced, but not at the same time in the two systems. In LD, sucrose exudation rose when plants were returned to standard light after the inductive cycle, i.e. after the LD stimulus had left the leaf blade. By contrast, during the DSD, sucrose was transported at the same time as the floral stimulus. Results are discussed together with the methods used to time stimulus translocation and their implications.
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circadian rhythms and the induction of flowering in the long day grass Lolium temulentum l
Plant Cell and Environment, 1994Co-Authors: Claire Perilleux, Georges Bernier, Jeanmarie KinetAbstract:Plants of Lolium temulentum L. strain Ceres were grown in 8-h short day (SD) for 45 d before being exposed either to a single long day (LD) or to a single 8-h SD given during an extended dark period. For LD induction, the critical photoperiod was between 12 and 14 h, and more than 16 h were needed for a maximal flowering response. During exposure to a single 24-h LD, the translocation of the floral stimulus began between the fourteenth and the sixteenth hours after the start of the light period, and was completed by the twenty-fourth hour. Full flowering was also induced by one 8-h SD beginning 4 or 28 h after the start of a 40-h dark period, i.e. by shifting 12 h forward or beyond the usual SD. The effectiveness of a so-called 'displaced short day' (DSD) was not affected by light quality and light intensity. With a mixture of incandescent and fluorescent lights at a total photosynthetic photon flux density of 400 mu mol m(-2) s(-1), a 4-h light exposure beginning 4 h after the start of a 40-h dark period was sufficient to induce 100% flowering. The flower-inducing effect of a single 8-h DSD was also assessed during a 64-h dark period. Results revealed two maxima at a 20-h interval. This fluctuation in light sensitivity suggests that a circadian rhythm is involved in the control of flowering of L. temulentum.
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reproductive development in Lolium temulentum l spike morphogenesis and grain set limitations
Journal of Experimental Botany, 1991Co-Authors: Claire Perilleux, Georges Bernier, Jeanmarie KinetAbstract:Reproductive development in cereals is not easy to investigate because their quantitative response to environmental factors makes it difficult to synchronize the plants. In this paper, one of our aims was to assess whether Lolium temulentum strain Ceres, a qualitative long-day grass, could serve as a model of reproductive development for cereals. The morphological patterns from floral transition to seed set were studied. A flowering scale was established to evaluate developmental rate during spike morphogenesis. Apex growth was found to increase according to biphasic kinetics; double ridge appearance marked the beginning of an exponential phase. Developmental progression and apical growth rate were both increased by giving repeated long days. In contrast, the final number of lateral spikelets (20-25) could not be manipulated after the beginning of long-day treatment. When plants were kept in continuous light from the beginning of induction, double ridges appeared on the fifth 24 h cycle. Spikelet initiation began in the upper mid-part of the spike, and then extended aeroand basipetally. The phase of spikelet initiation lasted 6 d, with 1-5 to 1-9 spikelets being produced daily. Within each spikelet, florets were initiated at an average rate of 1-3 primordia per day and developed acropetally. The first signs of apical site degeneration were observed in the most developed upper spikelets just before heading. Ear emergence occurred between the 20th and 25th cycles of continuous light; anthesis was observed 6 or 7 d later. The proportion of florets setting grain averaged about 40%. Grains were produced mainly in the lower spikelets while the upper mid-part of the inflorescence showed a much lower fertility rate. Complex developmental gradients described in this paper suggest that L. temulentum could serve as a model of reproductive development in cereals, with the added advantage of flowering in response to a single long-day.
