Australian Journal of Plant Physiology最新文献

{"title":"Polyamines as potential regulators of nutrient exchange across the peribacteroid membrane in soybean root nodules","authors":"L. Whitehead, S. Tyerman, D. Day","doi":"10.1071/PP01025","DOIUrl":"https://doi.org/10.1071/PP01025","url":null,"abstract":"The effect of cytoplasmic polyamines on peribacteroid membrane transport processes in soybean (Glycine max L.) was investigated. The concentration of free polyamines in soybean nodule cytoplasm has been estimated by others to be in the micromolar range. The H+ -ATPase was inhibited by 37 and 54% by 200 µM spermidine and putrescine, respectively. Spermine applied to the cytoplasmic face of the peribacteroid membrane was found to inhibit both inward and outward currents through a non-selective cation channel permeable to ammonium (K d 2.1 µM at –100 mV). Malate transport into intact symbiosomes was reduced by 15–30% by 15 mM spermidine, cadaverine and putrescine. A non-specific stimulation of malate transport by polycations was found to occur at concentrations in the micromolar range. The results suggest that polyamines can affect all the peribacteroid membrane transport processes tested. In particular, we conclude that the combined inhibitory effects of polyamines on the ATPase and the ammonium channel have the potential to reduce nitrogen supply to the plant in vivo. The possibility of competing polyamine and ureide synthesis in the nodule is discussed.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"4 1","pages":"675-681"},"PeriodicalIF":0.0,"publicationDate":"2001-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88726861","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}

{"title":"Nutrient transport across symbiotic membranes from legume nodules","authors":"D. Day, B. Kaiser, Rowena Thomson, M. Udvardi, S. Moreau, A. Puppo","doi":"10.1071/PP01028","DOIUrl":"https://doi.org/10.1071/PP01028","url":null,"abstract":"David A. Day , Brent N. Kaiser, Rowena Thomson, Michael K. Udvardi, Sophie Moreau and Alain Puppo","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"3 1","pages":"669-676"},"PeriodicalIF":0.0,"publicationDate":"2001-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86065599","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}

{"title":"Oscillations in proton transport revealed from simultaneous measurements of net current and net proton fluxes from isolated root protoplasts: MIFE meets patch-clamp","authors":"S. Tyerman, M. Beilby, J. Whittington, U. Juswono, I. Newman, S. Shabala","doi":"10.1071/PP01030","DOIUrl":"https://doi.org/10.1071/PP01030","url":null,"abstract":"Proton fluxes were measured non-invasively on patch-clamped protoplasts isolated from wheat roots using an external H + electrode to measure the electrochemical gradient in the external solution. Under voltage clamp in the whole-cell configuration, the H + fluxes across the plasma membrane could be measured as a function of voltage and time and correlated with the simultaneous measurements of membrane current. Protoplasts could exist in three states based on the current–voltage (I–V) curves and the flux–V curves. In the pump-state where the membrane voltage (Vm) was more negative than the electrochemical equilibrium potential for potassium (E K ), a net efflux of H + occurred that was voltage-dependent such that the efflux increased as Vm was clamped more positive. In the K-state, where Vm was close to E K , similar flux–V curves were observed. In the depolarised state where Vm was greater than E K the proton flux was characterised by a net influx of H + (H + -influx state) that reversed direction at more positive values of Vm. The inhibitory effect of DCCD and stimulatory effect of fusicoccin were used to correlate current and H + flux through the H + -ATPase for which there was reasonably good agreement within the limits of the flux measurements. Some protoplasts were kept in the whole-cell configuration for up to 3 h revealing slow sustained oscillations (period about 40 min) in H + flux that were in phase with oscillations in free-running Vm. These oscillations were also observed under voltage clamp, with membrane current in phase with H + flux, but which became damped out after a few cycles. The oscillations encompassed the pump-state, K + -state and H + -influx-state. The H +- flux–V curves and I–V curves were used to model the electrical characteristics of the plasma membrane with H + -ATPase, inward and outward K + rectifiers, a linear conductance, and a passive H + influx possibly through gated proton channels.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"1 1","pages":"591-604"},"PeriodicalIF":0.0,"publicationDate":"2001-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89547095","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}

{"title":"NAD(P) turnover in plant mitochondria","authors":"Stephanie C. Agius, A. Rasmusson, I. Møller","doi":"10.1071/PP00155","DOIUrl":"https://doi.org/10.1071/PP00155","url":null,"abstract":"An analytical procedure based on alkaline extraction and HPLC analysis was adapted for quantification of pyridine nucleotides in plant mitochondria. The amounts of NAD and NADP extracted from seven different species varied from 1.0 to 3.7 and 0 to 0.5 nmol (mg protein) –1 , respectively. Although NADP was found in four species, its reduced form was in all cases below the detection limit of 0.1 nmol (mg protein) –1 . The NAD pool was mainly oxidized in the absence of substrates. However, oxidation of substrates followed by anaerobiosis caused 50–92% NAD pool reduction, indicating that the majority of the NAD+ was metabolically active. The NAD reduction level in potato tuber mitochondria oxidizing malate varied with assay conditions. The highest level of reduction (>80%) was reached at anaerobiosis, at pH 6.5 and 7.2, conditions favouring malic enzyme (ME), whereas the lowest reduction level (0%) was observed at pH 7.5, conditions favouring malate dehydrogenase (MDH). Mitochondria incubated at 0°C without respiratory substrate showed a loss of endogenous NAD + which correlated with a decline in the rate of oxidation of NAD+ -linked substrates. The lost NAD+ was mainly recovered as breakdown products in both the surrounding medium and the mitochondria. When submitochondrial fractions were incubated with NAD + or NADP + , the highest rate of NAD(P)+metabolism was detected in the outer membrane fraction. The metabolites detected, adenosine monophosphate (AMP), nicotinamide mononucleotide (NMN) and adenosine, imply that several enzymes involved in pyridine nucleotide degradation, including an NAD pyrophosphatase, are localized to the outer membrane.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"3 1","pages":"461-470"},"PeriodicalIF":0.0,"publicationDate":"2001-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90252562","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}

{"title":"Root and shoot factors contribute to the effect of drought on photosynthesis and growth of the C4 grass Panicum coloratum at elevated CO2 partial pressures","authors":"S. Seneweera, O. Ghannoum, J. Conroy","doi":"10.1071/PP01007","DOIUrl":"https://doi.org/10.1071/PP01007","url":null,"abstract":"We examined the hypothesis that root and shoot factors influence growth responses to elevated CO2 of the C4 grass Panicum coloratum var. makarikiense cv. Bambatsi (NAD-ME malic enzyme subtype) when well watered and droughted. Plants were grown at CO2 partial pressures (pCO2) of 36 (ambient) and 100 Pa (elevated) in pot ed soil in growth chambers for 3 weeks with adequate water (day 0) before being subjected to 15 d of drought. At day 15, enhancement of shoot growth by elevated pCO2 was 70% under drought, and 44% when well watered. During the drought period, leaf CO2 assimilation rates (A) and stomatal conductance (g) (measured at 36 Pa CO2) declined after day 2, but the decline was faster at 36 Pa CO2, and by day 9, A was negligible and intercellular pCO2 had sharply increased compared with 100 Pa CO2. Changes in carbon metabolism and water relations occurred during drought and elevated CO2 generally delayed these changes. Leaf growth rates were higher at elevated CO2 at day 0 and during drought. Importantly, the decline in soil water content was slower at elevated pCO2 due to lower transpiration rates. This explained the slower decline in A, gand shoot water relations at elevated CO2 and indicates that root factors were responsible for their decline. In contrast, leaf growth rates were higher at elevated CO2, irrespective of soil water content. We conclude that both soil and leaf factors contribute to the greater growth response of P. coloratum to high CO2 under drought, and that reduced transpiration rates explains their enhanced growth.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"50 1","pages":"451-460"},"PeriodicalIF":0.0,"publicationDate":"2001-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90814982","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}

{"title":"Photosynthetic responses of temperate species to free air CO2 enrichment (FACE) in a grazed New Zealand pasture","authors":"S. Caemmerer, O. Ghannoum, J. Conroy, H. Clark, P. Newton","doi":"10.1071/PP01009","DOIUrl":"https://doi.org/10.1071/PP01009","url":null,"abstract":"A New Zealand temperate pasture is currently exposed to either ambient air or air enriched to 475 µbar CO2 using free-air CO2 enrichment (FACE) technology. Sheep graze the site regularly, which results in heterogeneity in nutrient return. To investigate leaf photosynthetic responses, leaf gas exchange characteristics and nitrogen (N) content were measured in two consecutive years in spring under standard conditions on Lolium perenne L. and Trifolium subterraneum L. and on Trifolium repens L. and Paspalum dilatatum Poir. in the second year only. Leaves of the three C3 species growing under FACE conditions had lower (up to 37% in 1998 and 22% in 1999) photosynthetic rates than leaves growing under ambient conditions, when measured at the same standard conditions of high light and 360-380 µbar CO2. Differences in photosynthetic rates were correlated with leaf N content and stomatal conductance when measured under these conditions. There was no difference in photosynthetic capacities between ambient or FACE grown P. dilatatum, a C4 grass. Photosynthetic N use efficiency (A/N) differed among species. For the C3 species A/N was on average 25% greater under FACE conditions and L. perenne had the highest (240 µmol CO2 mol N -1 s -1 ) and T. repens the lowest A/N (142 µmol CO2 mol N -1 s -1 ) under ambient CO2 partial pressure (p(CO2)). A/N of L. perenne was similar to that of P. dilatatum measured under ambient p(CO2) but 21% greater under FACE conditions. In the second year, leaf stable carbon isotope compositions (δ 13 C) were determined for P. dilatatum, L. perenne and T. repens to assess long-term responses of leaf transpiration efficiency. Using the difference in δ 13 C between ambient and FACE-grown P. dilatatum as a reference to difference in δ 13 C in ambient and FACE air, we concluded that the ratio of leaf intercellular to ambient p(CO2) (Ci/Ca) was similar between FACE and ambient grown L. perenne and T. repens.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"48 1","pages":"439-450"},"PeriodicalIF":0.0,"publicationDate":"2001-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90398456","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}

{"title":"The effect of rht genotype and temperature on coleoptile growth and dry matter partitioning in young wheat seedlings","authors":"T. Botwright, G. Rebetzke, Tony Condon, R. Richards","doi":"10.1071/PP01010","DOIUrl":"https://doi.org/10.1071/PP01010","url":null,"abstract":"Coleoptile length in wheat (Triticum aestivum L.) can be affected by several factors, including genotype, height-reducing genes and environmental factors, including temperature. There is little information on how these factors influence rate and duration of coleoptile growth to determine final coleoptile length in wheat. Coleoptile growth was determined for eight genotypes representing four different height-reducing genes: gibberellic acid (GA)-sensitive, standard height (rht), GA-sensitive semidwarfs (Rht8); and GA-insensitive, semidwarfs (Rht2). These were grown in the dark at three temperatures (12, 16 and 20˚C) and coleoptile lengths measured every 12˚Cd. Logistic growth curves were fitted to coleoptile growth data for each genotype with thermal time as the explanatory variable. Differences in final coleoptile length were largely attributable to differences in rate of coleoptile elongation although there were small differences in duration of growth between genotypes. The longer coleoptile of the rht wheats was achieved through the fastest rate of coleoptile elongation. Coleoptiles of Rht8 wheats were equivalent in final length to rht wheats at 107 mm, but achieved this through a slower growth rate (2.10 mm ˚Cd–1) combined with an increased duration of growth (57˚Cd). In contrast, the shorter coleoptiles of Rht2 wheats resulted from 25% slower rates of elongation than either Rht8 or rht. There were no interactions between the components of coleoptile growth and temperature, although a longer duration and a fast rate of growth combined to increase coleoptile length at 12˚C compared with either 16 or 20˚C. In a second experiment, dry matter partitioning and length of coleoptile, subcrown internode (SCI), shoot and roots were determined after 200˚Cd. In Rht2, the SCI and shoot were short while roots were longer than either Rht8 or rht. Reduced dry matter (DM) partitioning to the coleoptile and SCI and DM retention in the seed reduced the endosperm-use efficiency (EUE) of Rht compared with rht. EUE was poor also in Rht8, apparently through increased respiratory losses. Reduced partitioning of dry matter to coleoptiles and the SCI in Rht2 increased the root : shoot ratio compared with rht or Rht8. We conclude that either increased rate or duration of coleoptile growth could be targeted in a breeding program that aims to increase coleoptile length in wheat.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"40 1","pages":"417-423"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89539366","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}

{"title":"Ozone induces a differential accumulation of phenyalanine ammonia-lyase, chalcone synthase and chalcone isomerase RNA transcripts in sensitive and resistant bean cultivars","authors":"A. Paolacci, R. D'Ovidio, R. Marabottini, C. Nali, G. Lorenzini, M. Abenavoli, M. Badiani","doi":"10.1071/PP00095","DOIUrl":"https://doi.org/10.1071/PP00095","url":null,"abstract":"On exposure to a realistic ozone dose, an enhanced mRNA accumulation for phenyalanine ammonia-lyase (EC 4.3.1.5), naringenin–chalcone synthase [malonyl–CoA:4-coumaroyl–CoA malonyltransferase (cyclising); EC 2.3.1.74] and chalcone isomerase [flavanone lyase (decyclising); EC 5.5.1.6] genes, whose products are involved in the biosynthesis of phenylpropanoid molecules, flavonoid pigments and isoflavonoid phytoalexins, was observed in primary leaves of the bean (Phaseolus vulgaris L.) cv. Pinto. This cultivar was previously known to be ozone-sensitive on the basis of the appearance of macroscopic foliar injury, but not in coeval leaves of the bean cv. Groffy, known to be ozone-resistant on the basis of the aforementioned criterion. Distinct time patterns were observed in Pinto leaves for the ozone-dependent enhanced mRNA accumulation for the aforementioned genes, which in all cases largely preceded the appearance of visible injury symptoms. These results lend support to the view of ozone as an abiotic elicitor of plant defence responses. By analogy with other case studies, it is also suggested that proneness to develop visible ozone symptoms might rest on a sequence of molecular events similar to that leading to the hypersensitive response during plant–pathogen incompatible interactions.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"1 1","pages":"425-428"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83670055","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}

{"title":"Correlations between oxygen isotope ratios of wood constituents of Quercus and Pinus samples from around the world","authors":"M. Barbour, T. Andrews, G. Farquhar","doi":"10.1071/PP00083","DOIUrl":"https://doi.org/10.1071/PP00083","url":null,"abstract":"The oxygen isotope compositions of three wood constituents (the solvent-extractable portion, lignin and α-cellulose) were measured for samples collected from Quercus and Pinus trees around the world. Among Pinus samples all wood constituents were positively related to modelled δ18O of source water at the site, while among Quercus samples whole wood, lignin and α-cellulose showed positive relationships. The data support the hypothesis that many oxygen atoms in lignin exchanged with unenriched stem water during synthesis, rather than retaining the full isotopic signal from the molecular oxygen added during hydroxylation of the aromatic ring. The data also suggest that extraction of α-cellulose from wood samples is unnecessary for isotope studies looking at correlations with site parameters.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"1 1","pages":"335-348"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73319176","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}

{"title":"Ethylene production and post-pollination development in Dendrobium flowers treated with foreign pollen","authors":"S. Ketsa, K. Bunya-atichart, W. Doorn","doi":"10.1071/PP00048","DOIUrl":"https://doi.org/10.1071/PP00048","url":null,"abstract":"Dendrobium ‘Pompadour’ flowers fade early following pollination. This is associated with increased ethylene production and early epinasty. These effects are also produced by application of 1-aminocyclopropane-1-carboxylic acid (ACC) on the stigma. Pollen (one anther each) from Ruellia tuberosa L. (Acanthaceae) and Caesalpinia pulcherrima (L.) Sw. (Fabaceae) also increased ethylene production and caused early epinasty and fading. Pollen of Hibiscus schizopetalus (Mast.) Hook.f. (Malvaceae), in contrast, had no effect. R. tuberosa pollen increased ACC concentration and ACC synthase activity of the orchid flowers. Aminooxyacetic acid (AOA) pretreatment prior to R. tuberosa pollination prevented early fading, epinasty and the increase in ethylene production. It also prevented the increase in ACC concentration, and ACC synthase activity. Ovary growth was stimulated by Dendrobium ‘Pompadour’ pollinia, not by any of the incompatible pollen. Applied ACC did not promote ovary growth. It is concluded that incompatible pollen can hasten senescence and epinasty by increasing ACC synthase activity and ethylene production. Ovary growth, in contrast, is apparently not primarily regulated by ethylene.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"18 1","pages":"409-415"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88846220","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}