bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification and characterization of a locus (RTM1) that restricts long‐distance movement of tobacco etch virus in Arabidopsis thaliana
Authors: Mahajan Sunita K. , Chisholm Stephen T. , Whitham Steven A. , Carrington James C. 
Published: March 2003

SummaryScreens of Arabidopsis thaliana for susceptibility to tobacco etch virus (TEV) revealed that each of 10 ecotypes were able to support genome replication and cell‐to‐cell movement in inoculated leaves. However, only four ecotypes, including C24 and La‐er, supported complete infections in which TEV was able to replicate and move from cell to cell and long distances through the vasculature. The rates of cell‐to‐cell movement of a reporter‐tagged TEV strain (TEV–GUS) in inoculated leaves of C24 and Columbia (Col‐3) were similar, and infection foci continued to expand in both ecotypes through 10 days post‐inoculation. No visible or microscopic hypersensitive or cell death responses were evident in inoculated leaves of Col‐3 plants. Infection of neither C24 nor Col‐3 plants with TEV–GUS resulted in induction of PR‐1a gene expression, which is normally associated with active defence responses and systemic acquired resistance. The genetic basis for the restriction of long‐distance movement of TEV–GUS in Columbia was investigated using C24 × Col‐3 crosses and backcrosses and using La‐er× Col‐0 recombinant inbred lines. A dominant locus conditioning the restricted TEV infection phenotype was identified on chromosome 1 between markers ATEAT1 and NCC1 at approximately 14 cM in both genetic analyses. This locus was designated RTM1 (restricted TEV movement 1). It is proposed that RTM1 mediates a restriction of long‐distance movement through a mechanism that differs substantially from those conditioned by the dominant resistance genes normally associated with gene‐for‐gene interactions.
dCAPS, a simple technique for the genetic analysis of single nucleotide polymorphisms: experimental applications in Arabidopsis thaliana genetics
Authors: Neff Michael M. , Neff Joseph D. , Chory Joanne , Pepper Alan E. 
Published: March 2003

SummaryPCR‐based detection of single nucleotide polymorphisms is a powerful tool for the plant geneticist. Cleaved amplified polymorphic sequence analysis is the most widely used approach for the detection of single nucleotide polymorphisms. However, this technique is limited to mutations which create or disrupt a restriction enzyme recognition site. This paper presents a modification of this technique where mismatches in a PCR primer are used to create a polymorphism based on the target mutation. This technique is useful for following known mutations in segregating populations and genetic mapping of isolated DNAs used for positional based cloning of new genes. In addition, a computer program has been developed that facilitates the design of these PCR primers.
Magnesium ions promote assembly of channel‐like structures from beticolin 0, a non‐peptide fungal toxin purified from Cercospora beticola
Authors: Goudet Cyril , Véry Anne‐Aliénor , Milat Marie‐Louise , Ildefonse Michèle , Thibaud Jean‐Baptiste , Sentenac Hervé , Blein Jean‐Pierre 
Published: March 2003

SummaryBeticolins are toxins produced by the fungus Cercospora beticola. Using beticolin 0 (B0), we have produced a strong and Mg2+‐dependent increase in the membrane conductance of Arabidopsis protoplasts and Xenopus oocytes. In protein‐free artificial bilayers, discrete deflexions of current were observed (12 pS unitary conductance in symmetrical 100 mM KCl) in the presence of B0 (approximately 10 μM) and in the presence of nominal Mg2+. Addition of 50 μM Mg2+ induced a macroscopic current which could be reversed to single channel current by chelating Mg2+ with EDTA. Both unitary and macroscopic currents were ohmic. The increase in conductance of biological membranes triggered by B0 is therefore likely to originate from the ability of this toxin to organize itself into transmembrane pores in the presence of Mg2+. The pore is poorly selective, displaying permeability ratios PCl/PK, PNa/PK and PCa/PK close to 0.3, 0.65 and 0.4, respectively. Such channel‐like activity could be involved in the deleterious biological activity of the toxin, by causing the collapse of ionic and electrical gradients through biological membranes together with Ca2+ influx and scrambling of cellular signals.
Six Arabidopsis thaliana homologues of the human respiratory burst oxidase (gp91phox)
Authors: Torres Miguel Angel , Onouchi Hitoshi , Hamada Susuma , Machida Chiyoko , Hammond‐Kosack Kim E. , Jones Jonathan D. G. 
Published: March 2003

SummaryAn NADPH oxidase analogous to that in mammalian phagocytes has been hypothesized to produce reactive oxygen species (ROS) in the plant defence response. A. thaliana contains at least six gp91phox homologues, designated AtrbohA‐F (A. thaliana Respiratory Burst Oxidase Homologues), which map to different positions. Transcripts of three of these genes can be detected in healthy plants by RNA gel blot analyses. The Atrboh gene products are closely related to gp91phox and the intron locations suggest a common evolutionary origin. A putative EF‐hand Ca2+‐binding motif in the extended N‐terminal region of the Atrboh proteins suggests a direct regulatory effect of Ca2+ on the activity of the NADPH oxidase in plants.
Rhizobial lipochitooligosaccharide nodulation factors activate expression of the legume early nodulin gene ENOD12 in rice
Authors: Reddy Pallavolu M. , Ladha Jagdish K. , Ramos Marilou C. , Maillet Fabienne , Hernandez Rowena J. , Torrizo Lina B. , Oliva Norman P. , Datta Swapan K. , Datta Karabi 
Published: March 2003

Summary Lipochitooligosaccharide nodulation factors (Nod factors) produced by rhizobia are a major host range determinant. These factors play a pivotal role in the molecular signal exchange, infection and induction of symbiotic developmental responses in legumes leading to the formation of a nodule in which rhizobia carry out N2 fixation. Determining whether rice (

Oryza sativa) can respond to Nod factors could lead to strategies that would make rice amenable to develop a nitrogen‐fixing endosymbiotic association with rhizobia. We introduced into rice the promoter of the infection‐related gene

MtENOD12
(from

Medicago truncatula) fused to the β‐glucuronidase (GUS) reporter gene to serve as a molecular marker to aid in the detection of Nod factor signal perception by rice cells. Treatment of the transgenic rice roots with Nod factors (10–6–10–9m) under nitrogen‐limiting conditions induced MtENOD12‐GUS expression in cortical parenchyma, endodermis and pericycle. In contrast, chitooligosaccharide backbone alone failed to elicit such a response in the root tissues. These findings demonstrate that rice roots perceive Nod factors and that these lipochitooligosaccharides, but not simple chitin oligomers, act as signal molecules in activatingMtENOD12
in cortical parenchyma as in legumes. Exogenous application ofN‐naphthaleneacetic acid mimicked the Nod factor‐elicited tissue‐specific expression ofMtENOD12
in roots while cytokinins inhibited it, thus evidencing that Nod factors, auxin and cytokinins probably act on similar signaling elements responsible for the regulation ofMtENOD12
activation in rice. Taken together, these results suggest that at least a portion of the signal transduction machinery important for legume nodulation is likely to exist in rice.
Spatial specificity of H2O2‐generating oxalate oxidase gene expression during wheat embryo germination
Authors: Caliskan Mahmut , Cuming Andrew C. 
Published: March 2003

Summary Germin, a molecular marker of wheat embryo germination, is a protease‐resistant, apoplastic, homopentameric glycoprotein with peroxide‐generating oxalate oxidase activity. The spatial specificity of germin‐like oxalate oxidase (gl‐OXO) gene expression has been determined in tissues of germinating wheat embryos by a combination of histochemical, immunocytochemical and in situ hybridization techniques. The synthesis and accumulation of gl‐OXO mRNA and protein is localised within the enveloping tissues of the embryonic axis (particularly the coleorhiza) during the first 24 h of imbibition. By 48 h germination, gl‐OXO accumulation is detected throughout the root, with the exception of the postmitotic zone of cell elongation, where accumulation of its transcript is restricted to outer cell layers. At this time in the elongating shoot, gl‐OXO is restricted to the coleoptile where it is detected only in the epidermal cell layer, the vascular bundles and bundle sheath cells. In older seedlings (approximately 9 days post‐imbibition) gl‐OXO activity is detected in leaves, but only within the vascular bundles. These patterns of expression are consistent with the hypothesis that the biological function of gl‐OXO is to restrict cell growth by participating in cell‐wall restructuring through the local provision of hydrogen peroxide for cross‐linking of wall components.
Expression cloning of a fungal proline‐rich glycoprotein specific to the biotrophic interface formed in the Colletotrichum–bean interaction
Authors: Perfect Sarah E. , O’Connell Richard J. , Green Elaine F. , Doering‐Saad Christiane , Green Jonathan R. 
Published: March 2003

SummaryThe monoclonal antibody, UB25, recognises a glycoprotein specifically located at the biotrophic interface formed in the Colletotrichum lindemuthianum–bean interaction. The antibody labels the walls of intracellular hyphae and the interfacial matrix which separates them from the invaginated host plasma membrane. In Western blots, UB25 recognises a ladder of bands which are multiples of Mr 40.5 kDa. A full length cDNA encoding the glycoprotein recognised by UB25 has been isolated by expression cloning and designated CIH1 (Colletotrichum Intracellular Hypha 1). In vitro transcription/translation of CIH1, and transfection of mammalian COS cells, showed that UB25 recognised the expressed product in both procedures confirming that the clones isolated were true positives. Southern analysis of bean and C. lindemuthianum genomic DNA indicated that the CIH1 glycoprotein is fungally encoded and Northern analysis showed that it is only expressed in planta. Analysis of the deduced amino acid sequence of CIH1 indicates the presence of an N‐terminal signal sequence and two possible sites for N‐glycosylation. The N‐terminal domain of the mature protein is rich in proline and contains several short repetitive motifs. CIH1 is thus a fungal proline‐rich glycoprotein which appears to form a cross‐linked structure in planta and, as such, resembles plant cell wall proline‐ and hydroxyproline‐rich proteins. Possible functions for the CIH1 protein in the establishment and maintenance of biotrophy are discussed.
Co‐ and/or post‐translational modifications are critical for TCH4 XET activity
Authors: Campbell Paul , Braam Janet 
Published: March 2003

Summary
TCH4

encodes a xyloglucan endotransglycosylase (XET) of

Arabidopsis thaliana

. XETs endolytically cleave and religate xyloglucan polymers; xyloglucan is one of the primary structural components of the plant cell wall. Therefore, XET function may affect cell shape and plant morphogenesis. To gain insight into the biochemical function of TCH4, we defined structural requirements for optimal XET activity. Recombinant baculoviruses were designed to produce distinct forms of TCH4. TCH4 protein engineered to be synthesized in the cytosol and thus lack normal co‐ and post‐translational modifications is virtually inactive. TCH4 proteins, with and without a polyhistidine tag, that harbor an intact N‐terminus are directed to the secretory pathway. Thus, as predicted, the N‐terminal region of TCH4 functions as a signal peptide. TCH4 is shown to have at least one disulfide bond as monitored by a mobility shift in SDS‐PAGE in the presence of dithiothreitol (DTT). This disulfide bond(s) is essential for full XET activity. TCH4 is glycosylated

in vivo

; glycosidases that remove N‐linked glycosylation eliminated 98% of the XET activity. Thus, co‐ and/or post‐translational modifications are critical for optimal TCH4 XET activity. Furthermore, using site‐specific mutagenesis, we demonstrated that the first glutamate residue of the conserved DEIDFEFL motif (E97) is essential for activity. A change to glutamine at this position resulted in an inactive protein; a change to aspartic acid caused protein mislocalization. These data support the hypothesis that, in analogy to

Bacillus

β‐glucanases, this region may be the active site of XET enzymes.
Immediate early induction of mRNAs for ethylene‐responsive transcription factors in tobacco leaf strips after cutting
Authors: Suzuki Kaoru , Suzuki Nao , Ohme‐Takagi Masaru , Shinshi Hideaki 
Published: March 2003

SummaryTo investigate the functional relationship between the expression of genes for ethylene‐responsive transcription factors (ERFs) and the expression of ethylene‐responsive genes, we examined the expression of genes for ERFs and the expression of a reporter gene in transgenic tobacco that carried a gene for β‐glucuronidase (GUS) under the control of the ethylene‐responsive element, which includes four copies of the 11‐bp consensus sequence (designated the GCC‐box, TAAGAGCCGCC). In strips of leaves of transgenic tobacco, the GCC‐box‐mediated expression of the reporter gene was induced in response to treatment with ethylene. We also observed the ethylene‐independent immediate early induction of the synthesis of mRNAs for ERFs in wounded leaves and the enhancement of this induction by cycloheximide (CHX). Since CHX suppressed the induction of mRNAs for chitinase and GUS by ethylene, protein synthesis de novo was required for induction of the ethylene‐dependent GCC‐box‐mediated transcription of genes. In contrast, the enhancement by CHX of the wound‐induced expression of ERFs suggested that no synthesis of new proteins was required for the wounding signal transduction leading to rapid expression of ERFs. Methyl jasmonate did not stimulate the wounding‐responsive accumulation of ERF mRNAs, but it reduced such accumulation of mRNAs for ERF1, ERF2, ERF4 and the ethylene‐dependent GCC‐box‐mediated transcription of the reporter gene. Thus, the immediate early induction of the expression of genes for ERFs in strips of tobacco leaves appears to be a novel type of wound‐responsive activation of transcription. These results suggested that the expression of ERFs was not sufficient for activation of the GCC‐box‐mediated transcription but the expression of ERF1, ERF2 and ERF4, and that conversion of these ERFs by ethylene to their active form might be crucial for the GCC‐box‐mediated activation of the transcription of defense genes.
Genetic ablation of flowers in transgenicArabidopsis
Authors: Nilsson Ove , Wu Eric , Wolfe Diana S. , Weigel Detlef 
Published: March 2003

Summary We have created transgenic

Arabidopsis

plants in which a gene encoding the cell‐autonomous diphtheria toxin A chain (DT‐A) was expressed under the control of the

LEAFY (LFY)

promoter. This promoter is active both in emerging leaf primordia and young flowers, with the highest activity in flowers. The majority of

LFY::DT‐A

plants had normal vegetative development but lacked flowers, demonstrating that relatively widespread activity of a promoter does not exclude its possible use for ablating selected tissues, as long as differences in activity levels between different tissues are significant. We also found that flowers were replaced by empty bracts in

LFY::DT‐A

plants, suggesting that flower‐derived signals normally suppress bract development in

Arabidopsis

.
Divalent cation gating of an ammonium permeable channel in the symbiotic membrane from soybean nodules
Authors: Whitehead Lynne F. , Day David A. , Tyerman Stephen D. 
Published: March 2003

Summary The symbiotic membrane between N2‐fixing bacteroids and plant cytoplasm in nodules of soybean contains a sub‐picoSiemen cation channel permeable to NH4+. With millimolar concentrations of Ca2+ or Mg2+ on the cytoplasmic side, the channel rectifies current in the direction of cation influx to the cytoplasm. When Ca2+ is present on the bacteroid side of the membrane the current is rectified in the opposite direction. With submicromollar concentrations of divalent on both sides, the channel no longer rectifies. The channel is inhibited by verapamil on the bacteroid side of the membrane with a Kd of 2.6 μM. In the presence of millimolar concentrations of divalents on the cytoplasmic side, the conductance as a function of voltage is fitted by a simple Boltzmann equation with an effective gating charge equal to one. The voltage at which the conductance reaches 50% of maximum is dependent on external NH4+, shifting negative at lower concentrations. The time‐course of activation upon hyperpolarisation can be described by the Hodgkin‐Huxley equation with Ca2+present on the cytoplasmic side. With Mg2+ the channel activates with single exponential kinetics. The time constant for activation is weakly voltage dependent. Upon depolarisation of the membrane the channel deactivates with double exponential kinetics, the time constants being slightly voltage dependent. We propose a model of the channel in which divalent block is relieved when the blocking ion is dislodged by univalent cation flux into the pore. Mg2+ on the cytoplasmic side may function

in vivo

as the gating particle of the channel.
A novel NADPH‐dependent aldehyde reductase gene fromVigna radiataconfers resistance to the grapevine fungal toxin eutypine
Authors: Guillén Pedro , Guis Monique , Martínez‐Reina Gracia , Colrat Ségolène , Dalmayrac Sylvie , Deswarte Corine , Bouzayen Mondher , Roustan Jean‐Paul , Fallot Jean , Pech Jean‐Claude , Latché Alain 
Published: March 2003

Summary Eutypine, 4‐hydroxy‐3‐(3‐methyl‐3‐butene‐1‐ynyl) benzyl aldehyde, is a toxin produced by

Eutypa lata,

the causal agent of eutypa dieback of grapevines. It has previously been demonstrated that tolerance of some cultivars to this disease was correlated with their capacity to convert eutypine to the corresponding alcohol, eutypinol, which lacks phytotoxicity. We have thus purified to homogeneity a protein from

Vigna radiata

that exhibited eutypine‐reducing activity and have isolated the corresponding cDNA. This encodes an NADPH‐dependent reductase of 36 kDa that we have named

Vigna radiata

eutypine‐reducing enzyme (VR‐ERE), based on the capacity of a recombinant form of the protein to reduce eutypine into eutypinol. The strongest homologies (86.8%) of VR‐ERE at the amino acid level were found with CPRD14, a drought‐inducible gene of unknown function, isolated from

Vigna unguiculata

and with an aromatic alcohol dehydrogenase (71.7%) from

Eucalyptus gunnii

. Biochemical characterization of VR‐ERE revealed that a variety of compounds containing an aldehyde group can act as substrates. However, the highest affinity was observed with 3‐substituted benzaldehydes. Expression of a

VR‐ERE

transgene in

Vitis vinifera

cells cultured

in vitro

conferred resistance to the toxin. This discovery opens up new biotechnological approaches for the generation of grapevines resistant to eutypa dieback.
Molecular characterization of higher plant NAD‐dependent isocitrate dehydrogenase: evidence for a heteromeric structure by the complementation of yeast mutants
Authors: Lancien Muriel , Gadal Pierre , Hodges Michael 
Published: March 2003

Summary NAD‐dependent isocitrate dehydrogenase (IDH) is a key enzyme controlling the activity of the citric acid cycle. Despite more than 30 years of work, the plant enzyme remains poorly characterized. In this paper, a molecular characterization of the plant IDH is presented. Starting from probes defined according to sequence comparisons, three full‐length cDNAs named

Ntidha

,

Ntidhb

and

Ntidhc

encoding different IDH subunits have been isolated from a

Nicotiana tabacum

cell suspension library. Sequence comparisons of the tobacco IDH subunits with the

E. coli

NADP‐dependent enzyme, and the yeast IDH1 and IDH2 subunits suggested that only IDHa had the capacity to be catalytic as IDHb and IDHc were lacking certain residues implied in catalysis. The ability of antibodies raised against the recombinant IDHa protein to preferentially cross‐react with IDH2 indicated that IDHa was more closely related to IDH2 than to IDH1. Complementation of yeast single IDH mutants showed that IDHb and IDHc could replace the function of the yeast regulatory IDH1 subunit. Although IDHa was unable to complement the IDH2 mutant, its catalytic function was revealed by the ability of two heteromeric enzymes, composed of either IDHa with IDHb or IDHa with IDHc, to replace IDH function in a yeast double mutant lacking both subunits. Expression studies at the protein and mRNA levels show that each subunit is present in both root and leaf tissues and that the three IDH genes respond in the same way to nitrate addition. Taken together, such observations suggest that the physiologically active enzyme is composed of the three different subunits. These results show for the first time that the plant IDH is heteromeric and that IDH subunit composition appears to be conserved between plant and animal kingdoms.
Genetic identification of FIN2, a far red light‐specific signaling component ofArabidopsis thaliana
Authors: Soh Moon Soo , Hong Sung Hyun , Hanzawa Hiroko , Furuya Masaki , Nam Hong Gil 
Published: March 2003

Summary Phytochrome A (PhyA) mediates most, if not all various plant responses to far‐red (FR) light. Here, we report a novel genetic mutation that impairs a variety of responses in the PhyA‐signaling pathway of

Arabidopsis thaliana

. The mutation was isolated by screening seedlings that show reduced sensitivity to continuous far‐red (FRc) light irradiation, but not to continuous red (Rc) light irradiation. The mutation named

fin2–1

is not allelic to a

PHYA

mutation. Furthermore, immunoblot analysis indicated that the amount of the phytochrome A apoprotein in the

fin2–1

mutant was comparable to that in wild type. Seedling of the

fin2–1

mutant showed defects in hypocotyl growth inhibition and apical hook and cotyledon opening in FRc light but not in Rc light. The results showed that the mutation occurred in a downstream signaling component potentially specific to PhyA. Other PhyAmediated responses such as FR‐preconditioned blocking of greening, anthocyanin accumulation, reduction of gravitropic response, and expression of the

CAB

and

CHS

genes were impaired by the

fin2–1

mutation: the degree of the mutant effect on the responses was variable. However, FR light‐mediated seed germination and photoperiodic flowering responses were not affected significantly in the mutant. These results showed that FIN2 defines an upstream branch point in the PhyA signaling pathway.