Abstract：
:Futile plasma membrane cycling of ammonium (NH4+) is characteristic of low-affinity NH4+ transport, and has been proposed to be a critical factor in NH4+ toxicity. Using unidirectional flux analysis with the positron-emitting tracer 13N in intact seedlings of barley (Hordeum vulgare L.), it is shown that rapid, futile NH4+ cycling is alleviated by elevated K+ supply, and that low-affinity NH4+ transport is mediated by a K+-sensitive component, and by a second component that is independent of K+. At low external [K+] (0.1 mM), NH4+ influx (at an external [NH4+] of 10 mM) of 92 micromol g(-1) h(-1) was observed, with an efflux:influx ratio of 0.75, indicative of rapid, futile NH4+ cycling. Elevating K+ supply into the low-affinity K+ transport range (1.5-40 mM) reduced both influx and efflux of NH4+ by as much as 75%, and substantially reduced the efflux:influx ratio. The reduction of NH4+ fluxes was achieved rapidly upon exposure to elevated K+, within 1 min for influx and within 5 min for efflux. The channel inhibitor La3+ decreased high-capacity NH4+ influx only at low K+ concentrations, suggesting that the K+-sensitive component of NH4+ influx may be mediated by non-selective cation channels. Using respiratory measurements and current models of ion flux energetics, the energy cost of concomitant NH4+ and K+ transport at the root plasma membrane, and its consequences for plant growth are discussed. The study presents the first demonstration of the parallel operation of K+-sensitive and -insensitive NH4+ flux mechanisms in plants.
journal_name
J Exp Botjournal_title
Journal of experimental botanyauthors
Szczerba MW,Britto DT,Balkos KD,Kronzucker HJdoi
10.1093/jxb/erm309subject
Has Abstractpub_date
2008-01-01 00:00:00pages
303-13issue
2eissn
0022-0957issn
1460-2431pii
erm309journal_volume
59pub_type
杂志文章abstract：:The growth-defense trade-off in plant biology has gained enormous traction in the last two decades, highlighting the importance of understanding how plants deal with two of the greatest challenges for their survival and reproduction. It has been well established that in response to competition signals perceived by inf...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/erz237
更新日期：2019-07-05 00:00:00
abstract：:The determinism of bud bursting pattern along the 1-year-old shoot was studied at the molecular and morphological levels in the apple tree variety 'Lodi' which shows an acrotonic tendency. At the molecular level, the expression of KNAP2, which belongs to the class I KN1-like gene family, was studied. Measurements were...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erf063
更新日期：2002-11-01 00:00:00
abstract：:Accounting for almost one-fifth of the primary production on Earth, the unicellular eukaryotic group of diatoms plays a key ecological and biogeochemical role in our contemporary oceans. Furthermore, as producers of various lipids and pigments, and characterized by their finely ornamented silica cell wall, diatoms hol...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/ert387
更新日期：2014-06-01 00:00:00
abstract：:Salinity does not only stress plants but also challenges human life and the economy by posing severe constraints upon agriculture. To understand salt adaptation strategies of plants, it is central to extend agricultural production to salt-affected soils. Despite high impact and intensive research, it has been difficul...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/eru159
更新日期：2014-07-01 00:00:00
abstract：:Plants as photoautotrophic organisms are able to produce the carbohydrates they require and have developed mechanisms to co-ordinate carbohydrate production and its metabolism. Carbohydrate-derived signals regulate the expression of genes involved in both photosynthesis and metabolism, and control carbohydrate partiti...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/erg054
更新日期：2003-01-01 00:00:00
abstract：:The response of stomata to many environmental factors is well documented. Multiple signalling pathways for abscisic acid (ABA)-induced stomatal closure have been proposed over the last decades. However, it seems that exposure of a leaf for a long time (several days) to some environmental conditions generates a sort of...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/ert192
更新日期：2013-09-01 00:00:00
abstract：:Shipping of peaches to distant markets and storage require low temperature; however, cold storage affects fruit quality causing physiological disorders collectively termed 'chilling injury' (CI). In order to ameliorate CI, different strategies have been applied before cold storage; among them heat treatment (HT) has b...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erp267
更新日期：2009-01-01 00:00:00
abstract：:Citric acid is the predominant organic acid of citrus fruit. Degradation of citric acid occurs during fruit development, influencing fruit acidity. Associations of CitAco3 transcripts and citric acid degradation have been reported for citrus fruit. Here, transient overexpression of CitAco3 significantly reduced the ci...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erx187
更新日期：2017-06-15 00:00:00
abstract：:The tetrapyrrole biosynthetic pathway provides the vital cofactors and pigments for photoautotrophic growth (chlorophyll), several essential redox reactions in electron transport chains (haem), N- and S-assimilation (sirohaem), and photomorphogenic processes (phytochromobilin). While the biochemistry of the pathway is...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/err437
更新日期：2012-02-01 00:00:00
abstract：:Plant-atmosphere NH(3) exchange was studied in white clover (Trifolium repens L. cv. Seminole) growing in nutrient solution containing 0 (N(2) based), 0.5 (low N) or 4.5 (high N) mM NO(3)(-). The aim was to show whether the NH(3) exchange potential is influenced by the proportion of N(2) fixation relative to NO(3)(-) ...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：
更新日期：2002-01-01 00:00:00
abstract：:Plant nucleotide-binding domain, leucine-rich repeat receptor (NLR) proteins play important roles in recognition of pathogen-derived effectors. However, the mechanism by which plant NLRs activate immunity is still largely unknown. The paired Arabidopsis NLRs RRS1-R and RPS4, that confer recognition of bacterial effect...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erz571
更新日期：2020-03-25 00:00:00
abstract：:Rotundone was initially identified as a grape-derived compound responsible for the peppery aroma of Shiraz wine varieties. It has subsequently been found in black and white pepper and several other spices. Because of its potent aroma, the molecular basis for rotundone formation is of particular relevance to grape and ...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erv491
更新日期：2016-02-01 00:00:00
abstract：:Among dicotyledon families, Chenopodiaceae has the most C(4) species and the greatest diversity in structural forms of C(4). In subfamily Salicornioideae, C(4) photosynthesis has, so far, only been found in the genus Halosarcia which is now included in the broadly circumscribed Tecticornia. Comparative anatomical, cyt...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ern028
更新日期：2008-01-01 00:00:00
abstract：:Voltage dependence of ionic currents and ion fluxes in a walled, turgor-regulating cell were measured in Neurospora crassa. The hyphal morphology of the model organism Neurospora simplifies cable analysis of ionic currents to determine current density for quantitative comparisons with ion fluxes. The ion fluxes were m...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erm204
更新日期：2007-01-01 00:00:00
abstract：:The disruption of K(+) transport and accumulation is symptomatic of NH(4)(+) toxicity in plants. In this study, the influence of K(+) supply (0.02-40 mM) and nitrogen source (10 mM NH(4)(+) or NO(3)(-)) on root plasma membrane K(+) fluxes and cytosolic K(+) pools, plant growth, and whole-plant K(+) distribution in the...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ern190
更新日期：2008-01-01 00:00:00
abstract：:The process of selecting certain desirable traits for plant breeding may compromise other potentially important traits, such as defences against pests; however, specific phenotypic changes occurring over the course of domestication are unknown for most domesticated plants. Cranberry (Vaccinium macrocarpon) offers a un...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erq466
更新日期：2011-05-01 00:00:00
abstract：:Protein degradation in chloroplasts is carried out by a set of proteases that eliminate misfolded, damaged, or superfluous proteins. The ATP-dependent caseinolytic protease (Clp) is the most complex protease in plastids and has been implicated mainly in stromal protein degradation. In contrast, FtsH, a thylakoid membr...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erx066
更新日期：2017-04-01 00:00:00
abstract：:An investigation aimed at a better understanding of the molecular adaptation mechanisms of salt stress was carried out in 7-d-old tomato Solanum lycopersicum (L.) Mill cultivars Patio and 'F144', using a proteomic approach. Total proteins were extracted from radicles and hypocotyls collected from both non-saline contr...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erp075
更新日期：2009-01-01 00:00:00
abstract：:The activity of the protein kinase STN7, involved in phosphorylation of the light-harvesting complex II (LHCII) proteins, has been reported as being co-operatively regulated by the redox state of the plastoquinone pool and the ferredoxin-thioredoxin (Trx) system. The present study aims to investigate the role of plast...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ery415
更新日期：2019-02-05 00:00:00
abstract：:Branching is an important trait of plant development regulated by environmental signals. Phytochromes in Arabidopsis mediate branching in response to the changes in the red light:far-red light ratio (R:FR), the mechanisms of which are still elusive. Here it is shown that overexpression of CONSTANS-LIKE 7 (COL7) result...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ers376
更新日期：2013-02-01 00:00:00
abstract：:In order to investigate the genetic bases of the physiological syndrome mealiness that causes abnormal fruit softening and juice loss in apples, an integrative approach was devised, consisting of sensory, instrumental, biochemical, genetic, and genomic methods. High levels of activity of α-L-arabinofuranosidase (α-AFa...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/err146
更新日期：2011-08-01 00:00:00
abstract：:The efficient exclusion of excess Na from the cytoplasm and vacuolar Na(+) accumulation are the main mechanisms for the adaptation of plants to salt stress. This is typically carried out by transmembrane transport proteins that exclude Na(+) from the cytosol in exchange for H(+), a secondary transport process which is...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erp011
更新日期：2009-01-01 00:00:00
abstract：:Growth and productivity in important crop plants is limited by the inefficiencies of the C3 photosynthetic pathway. Introducing CO2-concentrating mechanisms (CCMs) into C3 plants could overcome these limitations and lead to increased yields. Many unicellular microautotrophs, such as cyanobacteria and green algae, poss...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/erx133
更新日期：2017-06-01 00:00:00
abstract：:The aim of this work was to investigate the importance of cytosolic phosphorylating glyceraldehyde 3-phosphate dehydrogenase (GAPC) in potato carbohydrate metabolism. For this purpose, the cytosolic isoform of phosphorylating GAPC was cloned and used for an antisense approach to generate transgenic potato plants that ...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/erj207
更新日期：2006-01-01 00:00:00
abstract：:HYL1 is an important regulator of microRNA (miRNA) biogenesis. A loss-of-function mutation of HYL1 causes the reduced accumulation of some miRNAs but fails to display the miRNA-deficient phenotypes of these miRNAs. In Arabidopsis, miR156 mediates phase transition through repression of SQUAMOSA PROMOTER-BINDING PROTEIN...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/err465
更新日期：2012-04-01 00:00:00
abstract：:Brassinosteroids (BRs) are essential for many biological processes in plants, however, little is known about their roles in early fruit development. To address this, BR levels were manipulated through the application of exogenous BRs (24-epibrassinolide, EBR) or a BR biosynthesis inhibitor (brassinazole, Brz) and thei...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ern093
更新日期：2008-01-01 00:00:00
abstract：:When plants encounter compacted soil, stomatal closure occurs and shoot growth slows. These responses occur in the absence of detectable changes in foliar water status. The use of genotypes with a reduced capacity to synthesize either ABA or ethylene has provided convincing evidence that ABA is responsible for providi...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：
更新日期：2002-01-01 00:00:00
abstract：:Capsella is a small genus within the mustard family (Brassicaceae). Its three species, however, show many evolutionary trends also observed in other Brassicaceae (including Arabidopsis) and far beyond, including transitions from a diploid, self-incompatible, obligatory outcrossing species with comparatively large and ...
journal_title：Journal of experimental botany
pub_type： 杂志文章,评审
doi：10.1093/jxb/erl158
更新日期：2006-01-01 00:00:00
abstract：:The aim of this study is to understand the parameters regulating calcium ion distribution in leaves. Accumulation of ions in leaf tissue is in part dependent on import from the xylem. This import via the transpiration stream is more important for ions such as calcium that are xylem but not phloem mobile and cannot the...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ern279
更新日期：2009-01-01 00:00:00
abstract：:The volatile compounds released by orthodox (desiccation-tolerant) seeds during ageing can be analysed using gas chromatography-mass spectrometry (GC-MS). Comparison of three legume species (Pisum sativum, Lathyrus pratensis, and Cytisus scoparius) during artificial ageing at 60% relative humidity and 50 °C revealed v...
journal_title：Journal of experimental botany
pub_type： 杂志文章
doi：10.1093/jxb/ers307
更新日期：2012-11-01 00:00:00
