Transgenic sugarcane (Saccharum officinarum L.) lines were created to express altered invertase isoform activity to elucidate the role(s) of invertase in the sucrose accumulation process. A sugarcane soluble acid invertase cDNA (SCINVm, AF062734) in the antisense orientation was used to decrease invertase activity. The Saccharomyces cerevisiae invertase gene (SUC2), fused with appropriate targeting elements, was used to increase invertase activity in the apoplast, cytoplasm and vacuole. A callus/liquid culture system was established to evaluate change in invertase activity and sugar concentration in the transgenic lines. Increased invertase activity in the apoplast led to rapid hydrolysis of sucrose and rapid increase of hexose in the medium. The cellular hexose content increased dramatically and the sucrose level decreased. Cells with higher cytoplasmic invertase activity did not show a significant change in the sugar composition in the medium, but did significantly reduce the sucrose content in the cells. Transformation with the sugarcane antisense acid invertase gene produced a cell line with moderate inhibition of soluble acid invertase activity and a 2-fold increase in sucrose accumulation. Overall, intracellular and extracellular sugar composition was very sensitive to the change in invertase activities. Lowering acid invertase activity increased sucrose accumulation.
{"title":"Metabolic engineering of invertase activities in different subcellular compartments affects sucrose accumulation in sugarcane cells","authors":"Hongmei Ma, H. Albert, R. Paull, P. Moore","doi":"10.1071/PP00029","DOIUrl":"https://doi.org/10.1071/PP00029","url":null,"abstract":"Transgenic sugarcane (Saccharum officinarum L.) lines were created to express altered invertase isoform activity to elucidate the role(s) of invertase in the sucrose accumulation process. A sugarcane soluble acid invertase cDNA (SCINVm, AF062734) in the antisense orientation was used to decrease invertase activity. The Saccharomyces cerevisiae invertase gene (SUC2), fused with appropriate targeting elements, was used to increase invertase activity in the apoplast, cytoplasm and vacuole. A callus/liquid culture system was established to evaluate change in invertase activity and sugar concentration in the transgenic lines. Increased invertase activity in the apoplast led to rapid hydrolysis of sucrose and rapid increase of hexose in the medium. The cellular hexose content increased dramatically and the sucrose level decreased. Cells with higher cytoplasmic invertase activity did not show a significant change in the sugar composition in the medium, but did significantly reduce the sucrose content in the cells. Transformation with the sugarcane antisense acid invertase gene produced a cell line with moderate inhibition of soluble acid invertase activity and a 2-fold increase in sucrose accumulation. Overall, intracellular and extracellular sugar composition was very sensitive to the change in invertase activities. Lowering acid invertase activity increased sucrose accumulation.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"2 1","pages":"1021-1030"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89382415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Drought resistance strategies of Ziziphus mauritiana Lamk. and peach (Prunus persica L.) were studied, focusing on changes in leaf water potential, carbon isotope composition, and solute and stress metabolite contents during an annual cycle under natural rainfed conditions at a field site in Zimbabwe. After a 100-d drought period, leaf water potential (yleaf) of peach trees decreased to –2.0 MPa, whereas yleaf of Z. mauritiana remained constant at –0.7 MPa. Values for the natural abundance of 13 C (d13 C) of bulk peach leaves as well as of total water-soluble compounds and soluble sugars of leaves increased gradually, resulting in significantly higher values as drought stress developed, indicative of increased water use efficiency (WUE). By the end of the dry season, both leaves and roots of peach exhibited osmotic adjustment, with significant accumulation of monosaccharide sugars, anions and cations in the leaves. Sorbitol and oxalate accounted for the greatest proportion of solute increases during drought, while foliar sucrose content decreased. In roots, soluble sugars such as sorbitol, glucose and fructose all increased, whereas root starch content decreased. For Z. mauritiana leaves, neither d13 C values nor soluble sugar concentrations changed markedly during the study period, and Z. mauritiana plants showed no osmotic adjustment during the dry season. Data indicate that the two species exhibited different strategies for coping with soil moisture deficits under field conditions. Although Z. mauritiana exhibited the capacity for osmotic adjustment in glasshouse experiments, the trees avoided drought stress in this investigation, which is an indication of a root system that has access to deeper moist soil layers. In contrast, the increased WUE in peach is likely due to stomatal control of water loss with onset of drought stress. The observed active osmotic adjustment to maintain turgor is in contrast to glasshouse studies, where no osmotic adjustment was found, and emphasizes the importance of field studies where stress develops more slowly.
{"title":"Contrasting adaptations to drought stress in field-grown Ziziphus mauritiana and Prunus persica trees: water relations, osmotic adjustment and carbon isotope composition","authors":"S. Arndt, W. Wanek, S. Clifford, M. Popp","doi":"10.1071/PP00022","DOIUrl":"https://doi.org/10.1071/PP00022","url":null,"abstract":"Drought resistance strategies of Ziziphus mauritiana Lamk. and peach (Prunus persica L.) were studied, focusing on changes in leaf water potential, carbon isotope composition, and solute and stress metabolite contents during an annual cycle under natural rainfed conditions at a field site in Zimbabwe. After a 100-d drought period, leaf water potential (yleaf) of peach trees decreased to –2.0 MPa, whereas yleaf of Z. mauritiana remained constant at –0.7 MPa. Values for the natural abundance of 13 C (d13 C) of bulk peach leaves as well as of total water-soluble compounds and soluble sugars of leaves increased gradually, resulting in significantly higher values as drought stress developed, indicative of increased water use efficiency (WUE). By the end of the dry season, both leaves and roots of peach exhibited osmotic adjustment, with significant accumulation of monosaccharide sugars, anions and cations in the leaves. Sorbitol and oxalate accounted for the greatest proportion of solute increases during drought, while foliar sucrose content decreased. In roots, soluble sugars such as sorbitol, glucose and fructose all increased, whereas root starch content decreased. For Z. mauritiana leaves, neither d13 C values nor soluble sugar concentrations changed markedly during the study period, and Z. mauritiana plants showed no osmotic adjustment during the dry season. Data indicate that the two species exhibited different strategies for coping with soil moisture deficits under field conditions. Although Z. mauritiana exhibited the capacity for osmotic adjustment in glasshouse experiments, the trees avoided drought stress in this investigation, which is an indication of a root system that has access to deeper moist soil layers. In contrast, the increased WUE in peach is likely due to stomatal control of water loss with onset of drought stress. The observed active osmotic adjustment to maintain turgor is in contrast to glasshouse studies, where no osmotic adjustment was found, and emphasizes the importance of field studies where stress develops more slowly.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"30 1","pages":"985-996"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76075813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Pritchard, Z. Ju, E. Santen, Jian-Wen Qiu, D. Weaver, S. Prior, H. Rogers
The effects of ele vated compared to current atmospheric CO2 concentration (720 and 365 µL L -1 , respec tively) on antioxidative enzymatic activities of two soybean (Glycine max (L.) Merr.) genotypes (R and S) grown in open-top field chambers were investigated. Enzymatic activities of leaves collected 40, 47, 54 and 61 d after plant ing were measured. Elevated CO2 significantly decreased activities of superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APOD, EC 1.11.1.7), gluta thione peroxidase (GPOD, EC 1.11.1.9) and glutathione reductase (GR, EC 1.6.4.2) in both genotypes. The activi ties of dehydroascorbate reductase (DAR, EC 1.8.5.1) and monodehydroascorbate reductase (MDAR, EC 1.1.5.4.) increased in genotype S, but decreased in genotype R under elevated CO2. Elevated CO2 decreased rubisco activity and rubisco, chlorophyll, carotenoids and total soluble protein contents in both genotypes. Results indicate that con stitutive antioxidative enzymatic activities may decrease in a high-CO2 world. Significant CO2 × genotype interac tions, however, suggest that there may be key genotypic differences in response patterns, potentially conferring differential resistance to biotic and abiotic stress.
{"title":"The influence of elevated CO2 on the activities of antioxidative enzymes in two soybean genotypes","authors":"S. Pritchard, Z. Ju, E. Santen, Jian-Wen Qiu, D. Weaver, S. Prior, H. Rogers","doi":"10.1071/PP99206","DOIUrl":"https://doi.org/10.1071/PP99206","url":null,"abstract":"The effects of ele vated compared to current atmospheric CO2 concentration (720 and 365 µL L -1 , respec tively) on antioxidative enzymatic activities of two soybean (Glycine max (L.) Merr.) genotypes (R and S) grown in open-top field chambers were investigated. Enzymatic activities of leaves collected 40, 47, 54 and 61 d after plant ing were measured. Elevated CO2 significantly decreased activities of superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APOD, EC 1.11.1.7), gluta thione peroxidase (GPOD, EC 1.11.1.9) and glutathione reductase (GR, EC 1.6.4.2) in both genotypes. The activi ties of dehydroascorbate reductase (DAR, EC 1.8.5.1) and monodehydroascorbate reductase (MDAR, EC 1.1.5.4.) increased in genotype S, but decreased in genotype R under elevated CO2. Elevated CO2 decreased rubisco activity and rubisco, chlorophyll, carotenoids and total soluble protein contents in both genotypes. Results indicate that con stitutive antioxidative enzymatic activities may decrease in a high-CO2 world. Significant CO2 × genotype interac tions, however, suggest that there may be key genotypic differences in response patterns, potentially conferring differential resistance to biotic and abiotic stress.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"155 1","pages":"1061-1068"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87215270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Doltchinkova, K. Georgieva, V. Kapchina-Toteva, Juergen Polle
In vitro cultured Gypsophila paniculata L. plants were used as a model to evaluate the effect of some cytokinins and anticytokinins on thylakoid surface charge. Influence of the cytokinins N-6-furfurylaminopurine (kinetin) and N1-(2-chloro-4-pyridyl)-N2-phenylurea (4-PU-30), cytokinin antagonists 2-chloro-4-cyclobutylamino-6-ethylamino-1,3,5-triazine and N-(4-pyridyl)-O-(4-chlorophenyl) carbamate on the pigment content, surface charge density (s ), fluorescence induction kinetics and millisecond-delayed light emission was studied. Our results showed that the chlorophyll (a+b) content significantly decreased after the 1st and the 2nd month of G. paniculata growth in the presence of the cytokinins kinetin and 4-PU-30. In our model system, cytokinins enhanced the number of open lateral buds and, as a consequence, more shoots per explant. Hence, chlorophyll synthesis was not inhibited but so-called ‘dilution of the pigments’ was available. Anticytokinins inhibited the formation of more than one shoot, and the chlorophyll content was not influenced significantly. The phenylurea cytokinin 4-PU-30 and anticytokinins increased the electrophoretic mobility, zeta potential and surface charge density of thylakoids after a longer time of treatment. Making thylakoid membranes more negatively charged, phenylurea cytokinin and anticytokinins increased the aggregation of the complexes and the energization of the membrane. Our results showed that plant growth regulators decreased the primary photochemical activity of photosystem II (estimated by the ratio Fv/Fm) and delayed fluorescence intensity in the 1st month. However, no significant changes were observed in these parameters in the 2nd month.
{"title":"Electrokinetic properties of thylakoids in in vitro cultured Gypsophila paniculata plants","authors":"V. Doltchinkova, K. Georgieva, V. Kapchina-Toteva, Juergen Polle","doi":"10.1071/PP99042","DOIUrl":"https://doi.org/10.1071/PP99042","url":null,"abstract":"In vitro cultured Gypsophila paniculata L. plants were used as a model to evaluate the effect of some cytokinins and anticytokinins on thylakoid surface charge. Influence of the cytokinins N-6-furfurylaminopurine (kinetin) and N1-(2-chloro-4-pyridyl)-N2-phenylurea (4-PU-30), cytokinin antagonists 2-chloro-4-cyclobutylamino-6-ethylamino-1,3,5-triazine and N-(4-pyridyl)-O-(4-chlorophenyl) carbamate on the pigment content, surface charge density (s ), fluorescence induction kinetics and millisecond-delayed light emission was studied. Our results showed that the chlorophyll (a+b) content significantly decreased after the 1st and the 2nd month of G. paniculata growth in the presence of the cytokinins kinetin and 4-PU-30. In our model system, cytokinins enhanced the number of open lateral buds and, as a consequence, more shoots per explant. Hence, chlorophyll synthesis was not inhibited but so-called ‘dilution of the pigments’ was available. Anticytokinins inhibited the formation of more than one shoot, and the chlorophyll content was not influenced significantly. The phenylurea cytokinin 4-PU-30 and anticytokinins increased the electrophoretic mobility, zeta potential and surface charge density of thylakoids after a longer time of treatment. Making thylakoid membranes more negatively charged, phenylurea cytokinin and anticytokinins increased the aggregation of the complexes and the energization of the membrane. Our results showed that plant growth regulators decreased the primary photochemical activity of photosystem II (estimated by the ratio Fv/Fm) and delayed fluorescence intensity in the 1st month. However, no significant changes were observed in these parameters in the 2nd month.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"44 1","pages":"1085-1091"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77379845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Verapamil application in ion transport studies on plant cells is widespread; however, the mechanism of its action is still poorly understood. Net flux of Ca 2+ , K + , Na + , H + and Cl – were measured in solution around oat seedlings using the non-invasive ion-selective microelectrode MIFE technique. The verapamil effect on intact plant tissues was a distinct immediate influx of monovalent cations, H + , K + or Na + . Pre-treatment with tetraethyl-ammonium, Cs + , Ba 2+ or Ca 2+ did not affect K + flux changes, whereas DMSO, Cd 2+ and vanadate increased verapamil-induced K + influx. Verapamil-induced K + flux increased with increased external KCl concentration or pH. Verapamil concentration up to 1 mM failed to shift Ca 2+ flux to efflux. Pre-treatment with adrenaline and dopamine agonists and antagonists led to changes in verapamil-induced ion flux, especially for Ca 2+ . We suggest that a transporter that allows entry of K + and Na + was the main system providing monovalent ion influx after verapamil application.
{"title":"Verapamil-induced kinetics of ion flux in oat seedlings","authors":"Olga Babourina, S. Shabala, I. Newman","doi":"10.1071/PP99182","DOIUrl":"https://doi.org/10.1071/PP99182","url":null,"abstract":"Verapamil application in ion transport studies on plant cells is widespread; however, the mechanism of its action is still poorly understood. Net flux of Ca 2+ , K + , Na + , H + and Cl – were measured in solution around oat seedlings using the non-invasive ion-selective microelectrode MIFE technique. The verapamil effect on intact plant tissues was a distinct immediate influx of monovalent cations, H + , K + or Na + . Pre-treatment with tetraethyl-ammonium, Cs + , Ba 2+ or Ca 2+ did not affect K + flux changes, whereas DMSO, Cd 2+ and vanadate increased verapamil-induced K + influx. Verapamil-induced K + flux increased with increased external KCl concentration or pH. Verapamil concentration up to 1 mM failed to shift Ca 2+ flux to efflux. Pre-treatment with adrenaline and dopamine agonists and antagonists led to changes in verapamil-induced ion flux, especially for Ca 2+ . We suggest that a transporter that allows entry of K + and Na + was the main system providing monovalent ion influx after verapamil application.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"26 1","pages":"1031-1040"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73135744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Bagnall, X. Wang, G. Scofield, R. Furbank, C. Offler, J. Patrick
In developing wheat grains (Triticum turgidum var. durum cv. Fransawi), post-sieve element transport of phloem-imported photoassimilates (sucrose) includes membrane transport, to and from the grain apoplasm, between symplasmically-isolated maternal and filial tissues. The cellular location and mechanism of these membrane transport steps were explored during rapid grain fill. Genomic Southern analysis indicated the presence of a multigene family of sucrose/H + symporters (SUTs). One or more SUTs were highly expressed in developing grains, as were P-type H + /ATPase(s) and a sucrose binding protein (SBP). Transcripts of these genes were detected in vascular parenchyma, nucellar projection and aleurone cells. Antibodies, raised against a SUT, an H + /ATPase and a SBP, were selectively bound to plasma membranes of vascular parenchyma cells, nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells. The nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells exhibited strong proton pumping activity. In contrast, SUT transport function was restricted to filial tissues containing modified aleurone/sub-aleurone transfer cells. Based on these findings, we conclude that SUTs expressed in maternal tissues do not function as sucrose/H + symporters. Membrane exchange from nucellar projection transfer cells to the endosperm cavity occurs by an as yet unresolved mechanism. Sucrose uptake from the endosperm cavity into filial tissues is mediated by a SUT localised to plasma membranes of the modified aleurone/sub-aleurone transfer cells.
小麦(Triticum turgidum var. durum cv.)韧皮部进口的光同化物(蔗糖)的筛后元素运输包括在同质分离的母体和子代组织之间进出籽粒质的膜运输。探讨了籽粒快速灌浆过程中这些膜转运步骤的细胞定位和机制。基因组南方分析表明存在一个多基因的蔗糖/H +同调体家族。一个或多个SUTs在发育中的谷物中高度表达，p型H + / atp酶(s)和蔗糖结合蛋白(SBP)也是如此。这些基因的转录本在维管薄壁细胞、珠心突起细胞和糊粉细胞中检测到。针对SUT、H + / atp酶和SBP的抗体被选择性地结合到血管薄壁细胞、核心投射转移细胞和修饰糊粉/亚糊粉转移细胞的质膜上。核状投射转移细胞和改性糊粉/亚糊粉转移细胞表现出较强的质子泵送活性。相比之下，SUT转运功能仅限于含有改性糊粉/亚糊粉转运细胞的子代组织。基于这些发现，我们得出结论，在母体组织中表达的SUTs不具有蔗糖/H +同调体的功能。从珠心投射转移细胞到胚乳腔的膜交换是通过一个尚未确定的机制发生的。蔗糖从胚乳腔进入子代组织的摄取是由定位于修饰糊粉/亚糊粉转移细胞质膜上的SUT介导的。
{"title":"Sucrose transport-related genes are expressed in both maternal and filial tissues of developing wheat grains","authors":"N. Bagnall, X. Wang, G. Scofield, R. Furbank, C. Offler, J. Patrick","doi":"10.1071/PP00012","DOIUrl":"https://doi.org/10.1071/PP00012","url":null,"abstract":"In developing wheat grains (Triticum turgidum var. durum cv. Fransawi), post-sieve element transport of phloem-imported photoassimilates (sucrose) includes membrane transport, to and from the grain apoplasm, between symplasmically-isolated maternal and filial tissues. The cellular location and mechanism of these membrane transport steps were explored during rapid grain fill. Genomic Southern analysis indicated the presence of a multigene family of sucrose/H + symporters (SUTs). One or more SUTs were highly expressed in developing grains, as were P-type H + /ATPase(s) and a sucrose binding protein (SBP). Transcripts of these genes were detected in vascular parenchyma, nucellar projection and aleurone cells. Antibodies, raised against a SUT, an H + /ATPase and a SBP, were selectively bound to plasma membranes of vascular parenchyma cells, nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells. The nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells exhibited strong proton pumping activity. In contrast, SUT transport function was restricted to filial tissues containing modified aleurone/sub-aleurone transfer cells. Based on these findings, we conclude that SUTs expressed in maternal tissues do not function as sucrose/H + symporters. Membrane exchange from nucellar projection transfer cells to the endosperm cavity occurs by an as yet unresolved mechanism. Sucrose uptake from the endosperm cavity into filial tissues is mediated by a SUT localised to plasma membranes of the modified aleurone/sub-aleurone transfer cells.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"116 1","pages":"1009-1020"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79536671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A mutant of Anabaena sp. strain PCC7120 requiring high CO2 was generated using Tn5 mutagenesis. This is the first data for a filamentous cyanobacterium. The mutant was capable of growing at 5% CO2, but incapable of growing at air levels of CO2. Southern hybridization analysis indicated that the Anabaena genome was inserted by the transposon at one site. The apparent photosynthetic affinity of the mutant to external dissolved inorganic carbon (DIC) was about 300 times lower that of the wild type (WT), and the medium alkalization rate as well as the carboxysomal carbonic anhydrase activity of the mutant was also lower than those of the WT. When the mutant was transferred from the culture medium bubbled with 5% CO2 to higher DIC (8.4% CO2) or 1% CO2, it showed similar responses to the WT. However, aberrant carboxysomes were found in the mutant cells through ultrastructural analysis, indicating it was most probably the wrong organization of the carboxysomes that eventually led to the inefficient operation of carboxysomal carbonic anhydrase and the subsequent defectiveness of the mutant in utilizing DIC.
{"title":"Construction and analysis of a high-CO2-requiring mutant of the cyanobacterium Anabaena sp. strain PCC7120","authors":"WuMatt Tianfu, Song Lirong, Liu Yongding","doi":"10.1071/PP99186","DOIUrl":"https://doi.org/10.1071/PP99186","url":null,"abstract":"A mutant of Anabaena sp. strain PCC7120 requiring high CO2 was generated using Tn5 mutagenesis. This is the first data for a filamentous cyanobacterium. The mutant was capable of growing at 5% CO2, but incapable of growing at air levels of CO2. Southern hybridization analysis indicated that the Anabaena genome was inserted by the transposon at one site. The apparent photosynthetic affinity of the mutant to external dissolved inorganic carbon (DIC) was about 300 times lower that of the wild type (WT), and the medium alkalization rate as well as the carboxysomal carbonic anhydrase activity of the mutant was also lower than those of the WT. When the mutant was transferred from the culture medium bubbled with 5% CO2 to higher DIC (8.4% CO2) or 1% CO2, it showed similar responses to the WT. However, aberrant carboxysomes were found in the mutant cells through ultrastructural analysis, indicating it was most probably the wrong organization of the carboxysomes that eventually led to the inefficient operation of carboxysomal carbonic anhydrase and the subsequent defectiveness of the mutant in utilizing DIC.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"72 5 1","pages":"1077-1083"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76726267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Sánchez, J. M. Soto, P. C. García, L. López-Lefebre, R. Rivero, J. Ruiz, L. Romero
The objective of the present work was to determine the effect of nitrogen toxicity on the metabolism of phenolic compounds and of oxidative stress in Phaseolus vulgaris L. cv. Strike. The nitrogen was applied to the nutrient solution as NH4NO3 at 5.4, 10.8, 16.2, 21.6 and 27 mM. The results indicate that the application of 27 mM N can be defined as toxic, as it drastically depressed growth of the green bean plants in our experiment. In addition, the abiotic stress from the application of this N dosage inhibited the enzymes polyphenol oxidase, peroxidase and cata-lase, and stimulated phenylalanine ammonia-lyase and superoxide dismutase activities. The result was foliar accumulation of phenolic compounds and hydrogen peroxide (H2O2). The accumulation of H2O2 also apparently caused a reduction in biomass production.
{"title":"Phenolic compounds and oxidative metabolism in green bean plants under nitrogen toxicity","authors":"E. Sánchez, J. M. Soto, P. C. García, L. López-Lefebre, R. Rivero, J. Ruiz, L. Romero","doi":"10.1071/PP00008","DOIUrl":"https://doi.org/10.1071/PP00008","url":null,"abstract":"The objective of the present work was to determine the effect of nitrogen toxicity on the metabolism of phenolic compounds and of oxidative stress in Phaseolus vulgaris L. cv. Strike. The nitrogen was applied to the nutrient solution as NH4NO3 at 5.4, 10.8, 16.2, 21.6 and 27 mM. The results indicate that the application of 27 mM N can be defined as toxic, as it drastically depressed growth of the green bean plants in our experiment. In addition, the abiotic stress from the application of this N dosage inhibited the enzymes polyphenol oxidase, peroxidase and cata-lase, and stimulated phenylalanine ammonia-lyase and superoxide dismutase activities. The result was foliar accumulation of phenolic compounds and hydrogen peroxide (H2O2). The accumulation of H2O2 also apparently caused a reduction in biomass production.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"55 1","pages":"973-978"},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87320956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The tribe Phaseoleae (family Leguminosae) is home to many of the annual food legumes cultivated in the tropics. Cowpea (Vigna unguiculata (L.) Walp.), Bambara groundnut (Vigna subterranea (L.) Verdc.), Kersting’s bean (Macrotyloma geocarpum L.), mung bean (Vigna radiata (L.) Wilczek) and common bean (Phaseolus vulgaris L.), all belonging to subtribe Phaseolinae, and together with soybean (Glycine max (L.) Merr., subtribe Glycininae) and pigeon pea (Cajanus cajan L., subtribe Cajaninae), are important members of the tribe Phaseoleae. These legumes are unique in their use of identical root chemical molecules to induce the expression of nodulation genes in their respective homologous microsymbionts during nodule formation. Of those studied so far, common bean, soybean, Bambara groundnut, Kersting’s bean and cowpea all use the isoflavones daidzein, genistein and coumestrol as root exudate signals to induce the expression of nod genes in their rhizobial partners. Additionally, members of the Phaseoleae tribe are easily recognised on the basis of their tropical biogeographic origin, broad host nodulation habit, route of Rhizobium entry into roots, chemotaxonomy and use of a common isoflavone biosynthetic pathway, determinate nodulation phenotype and internal nodule anatomy, xylem composition and transportable solutes of fixed N, site of NO3– reduction and metabolic response of N2-fed plants to NO3– supply. These shared traits and their potential application for agriculture are discussed in this review.
{"title":"Commonality of root nodulation signals and nitrogen assimilation in tropical grain legumes belonging to the tribe Phaseoleae.","authors":"F. Dakora","doi":"10.1071/PP00015","DOIUrl":"https://doi.org/10.1071/PP00015","url":null,"abstract":"The tribe Phaseoleae (family Leguminosae) is home to many of the annual food legumes cultivated in the tropics. Cowpea (Vigna unguiculata (L.) Walp.), Bambara groundnut (Vigna subterranea (L.) Verdc.), Kersting’s bean (Macrotyloma geocarpum L.), mung bean (Vigna radiata (L.) Wilczek) and common bean (Phaseolus vulgaris L.), all belonging to subtribe Phaseolinae, and together with soybean (Glycine max (L.) Merr., subtribe Glycininae) and pigeon pea (Cajanus cajan L., subtribe Cajaninae), are important members of the tribe Phaseoleae. These legumes are unique in their use of identical root chemical molecules to induce the expression of nodulation genes in their respective homologous microsymbionts during nodule formation. Of those studied so far, common bean, soybean, Bambara groundnut, Kersting’s bean and cowpea all use the isoflavones daidzein, genistein and coumestrol as root exudate signals to induce the expression of nod genes in their rhizobial partners. Additionally, members of the Phaseoleae tribe are easily recognised on the basis of their tropical biogeographic origin, broad host nodulation habit, route of Rhizobium entry into roots, chemotaxonomy and use of a common isoflavone biosynthetic pathway, determinate nodulation phenotype and internal nodule anatomy, xylem composition and transportable solutes of fixed N, site of NO3– reduction and metabolic response of N2-fed plants to NO3– supply. These shared traits and their potential application for agriculture are discussed in this review.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"501 1","pages":"885-892"},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80048326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although environmental factors such as precipitation and temperature are recognized as influencing pollen production, the impact of rising atmospheric carbon dioxide concentration ([CO2]) on the potential growth and pollen production of hay-fever-inducing plants is unknown. Here we present measurements of growth and pollen production of common ragweed (Ambrosia artemisiifolia L.) from pre-industrial [CO2] (280 mol mol–1) to current concentrations (370 mol mol–1) to a projected 21st century concentration (600 mol mol–1). We found that exposure to current and elevated [CO2] increased ragweed pollen production by 131 and 320%, respectively, compared to plants grown at pre-industrial [CO2]. The observed stimulations of pollen production from the pre-industrial [CO2] were due to an increase in the number (at 370 mol mol–1) and number and size (at 600 mol mol–1) of floral spikes. Overall, floral weight as a percentage of total plant weight decreased (from 21% to 13%), while investment in pollen increased (from 3.6 to 6%) between 280 and 600 mol mol–1 CO2. Our results suggest that the continuing increase in atmospheric [CO2] could directly influence public health by stimulating the growth and pollen production of allergy-inducing species such as ragweed.
{"title":"Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia), a known allergy-inducing species: implications for public health.","authors":"L. Ziska, F. Caulfield","doi":"10.1071/PP00032","DOIUrl":"https://doi.org/10.1071/PP00032","url":null,"abstract":"Although environmental factors such as precipitation and temperature are recognized as influencing pollen production, the impact of rising atmospheric carbon dioxide concentration ([CO2]) on the potential growth and pollen production of hay-fever-inducing plants is unknown. Here we present measurements of growth and pollen production of common ragweed (Ambrosia artemisiifolia L.) from pre-industrial [CO2] (280 mol mol–1) to current concentrations (370 mol mol–1) to a projected 21st century concentration (600 mol mol–1). We found that exposure to current and elevated [CO2] increased ragweed pollen production by 131 and 320%, respectively, compared to plants grown at pre-industrial [CO2]. The observed stimulations of pollen production from the pre-industrial [CO2] were due to an increase in the number (at 370 mol mol–1) and number and size (at 600 mol mol–1) of floral spikes. Overall, floral weight as a percentage of total plant weight decreased (from 21% to 13%), while investment in pollen increased (from 3.6 to 6%) between 280 and 600 mol mol–1 CO2. Our results suggest that the continuing increase in atmospheric [CO2] could directly influence public health by stimulating the growth and pollen production of allergy-inducing species such as ragweed.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"17 1","pages":"893-898"},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85389353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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