bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stacks on tracks: the plant Golgi apparatus traffics on an actin/ER network†
Authors: Boevink Petra , Oparka Karl , Cruz Simon Santa , Martin Barry , Betteridge Alan , Hawes Chris 
Published: March 2003

Summary We have visualized the relationship between the endoplasmic reticulum (ER) and Golgi in leaf cells of

Nicotiana clevelandii

by expression of two Golgi proteins fused to green fluorescent protein (GFP). A fusion of the

trans

‐membrane domain (signal anchor sequence) of a rat sialyl transferase to GFP was targeted to the Golgi stacks. A second construct that expressed the

Arabidopsis

H/KDEL receptor homologue aERD2, fused to GFP, was targeted to both the Golgi apparatus and ER, allowing the relationship between these two organelles to be studied in living cells for the first time. The Golgi stacks were shown to move rapidly and extensively along the polygonal cortical ER network of leaf epidermal cells, without departing from the ER tubules. Co‐localization of F‐actin in the GFP‐expressing cells revealed an underlying actin cytoskeleton that matched precisely the architecture of the ER network, while treatment of cells with the inhibitors cytochalasin D and N‐ethylmaleimide revealed the dependency of Golgi movement on actin cables. These observations suggest that the leaf Golgi complex functions as a motile system of actin‐directed stacks whose function is to pick up products from a relatively stationary ER system. Also, we demonstrate for the first time

in vivo

brefeldin A‐induced retrograde transport of Golgi membrane protein to the ER.
High‐resolution histographical mapping of glucose concentrations in developing cotyledons ofVicia fabain relation to mitotic activity and storage processes: glucose as a possible developmental trigger
Authors: Borisjuk Ljudmilla , Walenta Stefan , Weber Hans , Mueller‐Klieser Wolfgang , Wobus Ulrich 
Published: March 2003

Summary Previous studies provided evidence that the carbohydrate status triggers developmental processes in the growing cotyledons of

Vicia faba

. We describe here the high‐resolution mapping of glucose concentrations in tissue sections of developing faba bean cotyledons by quantitative bioluminescence and single‐photon imaging. Patterns of local glucose distributions are compared with tissue cell type, mitotic index and the distribution pattern of starch. During cotyledon differentiation, gradients in the glucose concentration emerge which are related to the particular cell type. Higher concentrations are found in non‐differentiated premature regions of the cotyledon whereas mature starch‐accumulating regions contain particularly low concentrations of glucose. In addition, glucose concentration is correlated to mitotic activity. The glucose distribution pattern is therefore related to the developmental gradient. Our data provide for the first time evidence for steep glucose gradients across developing plant embryos and favour the idea that sugar gradients may have morphogenic functions in developing cotyledons.
Higher plants possess two structurally different poly(ADP‐ribose) polymerases
Authors: Babiychuk Elena , Cottrill Phillippa B. , Storozhenko Sergei , Fuangthong Mayuree , Chen Yimin , O’Farrell Minnie K. , Van Montagu Marc , Inzé Dirk , Kushnir Sergei 
Published: March 2003

SummaryOne of the immediate reactions of the mammalian cell to many environmental stresses is a massive synthesis of poly(ADP‐ribose), catalyzed by poly(ADP‐ribose) polymerase (PARP). Most of the biological functions attributed to PARP are inferred from experimentation with mammalian cells. In plants, the biology of PARP may be more complicated and diverse than was previously thought. Two poly(ADP‐ribose) polymerase homologues were found in plants, the classical Zn‐finger‐containing polymerase (ZAP) and the structurally non‐classical PARP proteins (APP and NAP), which lack the characteristic N‐terminal Zn‐finger domain. By enzymatic and cytological experiments the recombinant APP protein was shown to be located in the nucleus and to possess DNA‐dependent poly(ADP‐ribose) polymerase activity in yeast. The nuclear localization was further confirmed by the analysis of transgenic tobacco plants that expressed a translational gene fusion between APP and the bacterial β‐glucuronidase. The app promoter was transcriptionally up‐regulated in cells pre‐determined to die because of deficiency in a DNA ligase I.
Tissue localization of expansins in deepwater rice
Authors: Cho Hyung‐Taeg , Kende Hans 
Published: March 2003

Summary Expansins are a family of proteins capable of inducing stress relaxation of isolated cell walls. In earlier studies, we showed that the expression of expansin genes in deepwater rice (

Oryza sativa

L.) is regulated by developmental, hormonal and environmental stimuli. Here, we describe the spatial distribution pattern of expansin transcripts and proteins in tissues and organs of deepwater rice using

in situ

mRNA hybridization and immunohistochemical analysis. Expansin transcripts and proteins are present at high levels in the growing internodal epidermis, which has thick cell walls and acts, therefore, as a growth‐limiting cell layer. Expansins are also concentrated in the differentiating vascular bundles of internodes. In the primary root, expansins are predominantly expressed in the tip region, particularly in the epidermis, differentiating vascular cylinder, and around the pericyle. Developing adventitious roots and lateral root primordia also contain high levels of expansin mRNA. In the shoot apex, expansin transcripts are abundant in the emerging leaf primordia. Our results indicate that expansins play an important role in the expansion and differentiation of plant tissues and organs.
Control of expression of a gene encoding an extensin by phytochrome and a blue light receptor in spores ofAdiantum capillus‐venerisL.
Authors: Uchida Kenko , Muramatsu Takamichi , Jamet Elisabeth , Furuya Masaki 
Published: March 2003

Summary In the present study, using a newly developed fluorescent differential display technique, we have carried out large‐scale screening for genes whose expression was regulated by phytochrome and antagonistically by a blue light receptor in the spores of the fern

Adiantum capillus‐veneris

L. Spores after imbibition were briefly irradiated with red, red/blue or blue light and collected 8 h after the irradiation. Total RNA was isolated from each sample and used to make cDNA with an oligo‐dT primer. The cDNA was then used as a template for PCR with the oligo‐dT primer and 80 arbitrary primers. The resulting PCR products were analyzed by an automated fluorescent DNA sequencer. Among 8000 displayed bands, we identified 15 upregulated and four down‐regulated bands by red light, and this red light effect was irreversibly reversed by blue light. We cloned one of the up‐regulated cDNA fragments and used it to screen a cDNA library prepared from the spores. The isolated insert is predicted to encode Ser‐(Pro)

n

repeats and showed homology with cell wall‐associated extensins. The expression of this cDNA was induced 8 h after a red light treatment and the red light induction was photoreversibly prevented by far‐red light and photo‐irreversibly by blue light. The mRNA of this gene was detectable 4 h after red light irradiation and gradually increased in germinating spores.
Characterisation of the ethanol‐induciblealcgene expression system for transgenic plants
Authors: Salter Michael G. , Paine Jacqueline A. , Riddell Kay V. , Jepson Ian , Greenland Andrew J. , Caddick Mark X. , Tomsett A. Brian 
Published: March 2003

Summary We describe a chemically induced gene control mechanism for plants based on the ALCR transcription factor and

alcA

promoter of

Aspergillus nidulans

, which we have called the

alc

system. Ethanol, the chemical inducer, is not toxic at levels required for induction, and can be applied to the plants by spraying, root drenching and addition to liquid growth media. The

alc

system is very sensitive to ethanol and the induction is rapid; 0.01% (1.7 mM) ethanol in liquid growth media initiates chloramphenicol acetyl transferase (CAT) reporter gene expression within 4 h, with maximal expression occurring after 4 days. In the complete absence of ethanol, there is no detectable expression of CAT, nor do we observe induction in plants subjected to wound, cold or drought stress, or following treatment with either salicylic acid or methyl jasmonate. However, extreme anoxia resulting in elevated levels of alcohol dehydrogenase activity in both roots and leaves gave substantial induction of CAT in leaves but not in roots. We believe that the

alc

system will have broad utility in the exogenous control of plant gene expression in pure science and that it also has considerable potential in agriculture.
Activation of plant defense responses and sugar efflux by expression of pyruvate decarboxylase in potato leaves
Authors: Tadege Million , Bucher Marcel , Stähli Walter , Suter Marianne , Dupuis Isabelle , Kuhlemeier Cris 
Published: March 2003

Summary When plants are infected with avirulent pathogens, a selected group of plant cells rapidly die in a process commonly called the hypersensitive response (HR). Some mutations and overexpression of some unrelated genes mimic the HR lesion and associated defense responses. In all of these situations, a genetically programmed cell death pathway is activated wherein the cell actively participates in killing itself. Here we report a developmentally and environmentally regulated HR‐like cell death in potato leaves constitutively expressing bacterial pyruvate decarboxylase (PDC). Lesions first appeared on the tip of fully expanded source leaves. Lesion formation was accompanied by activation of multiple defense responses and resulted in a significant resistance to

Phytophthora infestans

. The transgenic plants showed a five‐ to 12‐fold increase in leaf tissue acetaldehyde and exported two‐ to 10‐fold higher amounts of sucrose compared to the wild‐type. When plants were grown at a higher temperature, both the lesion phenotype and sucrose export were restored to wild‐type situations. The reduced levels of acetaldehyde at the elevated temperature suggested that the interplay of acetaldehyde with environmental and physiological factors is the inducer of lesion development. We propose that sugar metabolism plays a crucial role in the execution of cell death programs in plants.
TheArabidopsis HAL2‐like gene family includes a novel sodium‐sensitive phosphatase
Authors: Gil‐Mascarell Rosario , López‐Coronado José M. , Bellés José M. , Serrano Ramón , Rodríguez Pedro L. 
Published: March 2003

Summary The yeast

HAL2

gene encodes a lithium‐ and sodium‐sensitive phosphatase that hydrolyses 3′‐phosphoadenosine‐5′‐phosphate (PAP). Salt toxicity in yeast results from Hal2 inhibition and accumulation of PAP, which inhibits sulphate assimilation and RNA processing. We have investigated whether the model plant

Arabidopsis thaliana

contains sodium‐sensitive PAP phosphatases. The

Arabidopsis HAL2

‐like gene family is composed of three members:

AtAHL

and

AtSAL2

, characterized in the present work, and the previously identified

AtSAL1

. The

AtAHL

and

AtSAL2

cDNAs complement the auxotrophy for methionine of the yeast

hal2

mutant and the recombinant proteins catalyse the conversion of PAP to AMP in a Mg2+‐dependent reaction sensitive to inhibition by Ca2+ and Li+. The PAP phosphatase activity of AtAHL is sensitive to physiological concentrations of Na+, whereas the activities of AtSAL1 and AtSAL2 are not. Another important difference is that AtAHL is very specific for PAP while AtSAL1 and AtSAL2 also act as inositol polyphosphate 1‐phosphatases. AtAHL constitutes a novel type of sodium‐sensitive PAP phosphatase which could act co‐ordinately with plant sulphotransferases and serve as target of salt toxicity in plants.
Specific checkpoints regulate plant cell cycle progression in response to oxidative stress
Authors: Reichheld Jean‐Philippe , Vernoux Teva , Lardon Filip , Van Montagu Marc , Inzé Dirk 
Published: March 2003

Summary The effects of oxidative stress on plant cell cycle progression were studied both in cell suspensions and
in planta
. Oxidative stress of variable severity was imposed by the addition of different concentrations of the methyl‐quinone, menadione, into the growth media. In cell suspensions, flow cytometry analyses demonstrated that low concentrations (20–50 μM) of menadione impaired the G1/S transition, slowed DNA replication, and delayed the entry into mitosis. Furthermore, cells in G1 were more sensitive to menadione‐mediated oxidative stress than cells in S phase. Cell cycle arrest was associated with an inhibition of the activity of cyclin‐dependent kinases, cell cycle gene expression, and a concomitant activation of stress genes. Menadione‐mediated oxidative stress was shown to have very similar effects on tobacco plants, suggesting that a general regulation mechanism takes place in plants. These results define an oxidative stress checkpoint pathway that modulates both the expression of the core cell cycle genes and oxidative defence genes. Redox sensing could be of key importance in controlling cell cycle progression in environmental stress conditions.
The HMG‐I/Y protein PF1 stimulates binding of the transcriptional activator GT‐2 to the PHYA gene promoter
Authors: Martínez‐García Jaime F.. , Quail Peter H.. 
Published: March 2003

SummaryThe DNA‐binding proteins PF1 and GT‐2 are factors that bind to different functionally defined, positively acting cis‐elements in the PHYA genes of oat and rice, respectively. PF1 is an HMG‐I/Y protein, with its cognate cis‐element being an AT‐rich sequence, designated PE1, whereas GT‐2 is a transcriptional activator with twin DNA binding domains that recognize a triplet of GT‐boxes in a complex motif designated GTE. To further define the DNA‐binding activity of PF1 and to explore potential inter‐relationships between the two factors, we have performed a series of in vitro DNA‐binding experiments with both PE1 and GTE target sites. The data show that, consistent with its membership of the HMG‐I/Y protein family, PF1 can bend DNA when bound to PE1. In addition, PF1 can bind promiscuously, with varying affinity, to other AT‐containing motifs, including GTE. When co‐incubated with GT‐2, PF1 enhances the specific DNA‐binding activity of GT‐2 toward GTE, the first report of such activity for a plant HMG‐I/Y protein. This enhancement takes place without demonstrable physical contact between the two proteins, suggesting the possibility of a novel, indirect mechanism of recruitment involving DNA target‐site pre‐conditioning. The evidence indicates therefore that PF1 and GT‐2 do not perform functionally equivalent roles in positively regulating oat and rice PHYA gene expression. However, the data suggest the possibility that PF1 may act as an architectural factor, promiscuously recognizing a spectrum of AT‐containing elements in plant promoters, with the general function of catalyzing enhanced binding of conventional cognate transcriptional regulators to these elements via DNA bending.
A single locus determines sensitivity to bacterial flagellin in Arabidopsis thaliana
Authors: Gómez‐Gómez Lourdes , Felix Georg , Boller Thomas 
Published: March 2003

SummaryPeptides corresponding to the most conserved domain of eubacterial flagellin act as potent elicitors in cells of different plant species. In intact Arabidposis thaliana seedlings these peptides (flg22 and flg15) caused callose deposition, induction of genes coding for pathogenesis‐related proteins and a strong inhibition of growth. Half‐maximal growth inhibition occurred at peptide concentrations of approximately 100 nM. In contrast, peptides representing the corresponding flagellin domains of the plant‐associated bacteria A. tumefaciens and R. meliloti were inactive even at concentrations of 10 μM. With the exception of Ws‐0, all ecotypes of A. thaliana tested were sensitive to flg22. Crosses of Ws‐0 with the sensitive ecotypes Col‐0 and La‐er, respectively, resulted in sensitive F1 seedlings. In the F2 generation of both crosses, sensitivity segregated as a single trait with markers of chromosome 5 and a ratio of 3:1. Dominance of the locus sensing flagellin, termed FLS‐1, suggests that it encodes an element which is important for the perception of the flagellin signal.
Transfer of rps14 from the mitochondrion to the nucleus in maize implied integration within a gene encoding the iron–sulphur subunit of succinate dehydrogenase and expression by alternative splicing
Authors: Figueroa Pablo , Gómez Isabel , Holuigue Loreto , Araya Alejandro , Jordana Xavier 
Published: March 2003

SummaryThe maize mitochondrial genome does not contain a gene coding for ribosomal protein S14. In this paper we show that the functional rps14 gene was translocated to the nucleus and acquired the signals conferring expression and product targeting to the mitochondrion in a way not previously described. Transferred rps14 was found integrated between both exons of a gene encoding the iron–sulphur subunit of the respiratory complex II (sdh2). Sdh2 exon 1 and rps14 were separated by a typical plant nuclear intron that was spliced to give a mature poly(A)+ mRNA of 1.4 kb. This processed mRNA encoded a chimeric SDH2 (truncated)–RPS14 polypeptide, and we show that this chimeric polypeptide is targeted into isolated plant mitochondria, where it is proteolytically processed in a complex way. An alternative splicing event utilizing the same 5′ splice site and a different downstream 3′ splice site generated a second mature poly(A)+ mRNA of 1.3 kb that contained both sdh2 exons. This sdh2 transcript encoded an SDH2 polypeptide highly conserved compared with its homologues in other organisms, and it contained the three cysteine‐rich clusters that made up the three non‐heme iron–sulphur centres responsible for electron transport. To our knowledge, these results constitute the first evidence of alternative splicing playing a role in the expression and targeting of two mitochondrial proteins with different functions from the same gene.
Deficiency in phytoalexin production causes enhanced susceptibility of Arabidopsis thaliana to the fungus Alternaria brassicicola
Authors: Thomma Bart P. H. J. , Nelissen Inge , Eggermont Kristel , Broekaert Willem F. 
Published: March 2003

SummaryThe phytoalexin‐deficient Arabidopsis mutant pad3‐1, which is affected in the production of the indole‐type phytoalexin camalexin, has previously been shown not to display altered susceptibility to either the bacterium Pseudomonas syringae (Glazebrook & Ausubel 1994; Proc. Natl. Acad. Sci. USA, 91: 8955–8959) or the biotrophic fungi Peronospora parasitica (Glazebrook et al. 1997; Genetics, 146: 381–392) and Erysiphe orontii (Reuber et al. 1998; Plant J. 16: 473–485). We now show that this mutant is markedly more susceptible than its wild‐type parental line to infection by the necrotrophic fungus Alternaria brassicicola, but not to Botrytis cinerea. A strong camalexin response was elicited in wild‐type plants inoculated with either Alternaria brassicicola or Botrytis cinerea, whereas no camalexin could be detected in pad3‐1 challenged with these fungi. Hence, PAD3 appears to be a key determinant in resistance to at least A. brassicicola. The induction of salicylate‐dependent and jasmonate/ethylene‐dependent defense genes was not reduced in Alternaria‐challenged pad3‐1 plants compared to similarly treated wild‐type plants. Camalexin production could not be triggered by exogenous application of either salicylate, ethylene or jasmonate and was not, or not strongly, reduced in mutants with defects in perception of these defense‐related signal molecules. Camalexin‐production appears to be controlled by a pathway that exhibits little cross‐talk with salicylate‐, ethylene‐ and jasmonate‐dependent signalling events.
Ac as a tool for the functional genomics of rice
Authors: Enoki Hiroyuki , Izawa Takeshi , Kawahara Mihoko , Komatsu Mai , Koh Serry , Kyozuka Junko , Shimamoto Ko 
Published: March 2003

SummaryTo examine whether the maize autonomous transposable element Ac can be used for the functional analysis of the rice genome, we used Southern blot analysis to analyze the behaviour of Ac in 559 rice plants of four transgenic families through three successive generations. All families showed highly active transposition of Ac, and 103 plants (18.4%) contained newly transposed Ac insertions. In nine of the 12 independent transpositions analyzed, their germinal transmission was detected. Partial sequencing of 99 Ac‐flanking sequences revealed that 21 clones exhibited significant similarities with protein‐coding genes in databases and four of them matched rice cDNA sequences. These results indicate preferential Ac transposition into protein‐coding rice genes. To examine the feasibility of PCR‐based screening of gene knockouts in rice Ac plants, we prepared bulked genomic DNA from the leaves of approximately 6000 rice Ac plants and pooled the DNA according to a three‐dimensional matrix. Of 14 randomly selected genes, two gene knockouts were identified, and one encoding a rice cytochrome P450 (CYP86) gene was shown to be stably inherited to the progeny. Together, these results suggest that Ac can be efficiently used for the functional analysis of the rice genome.
Developmental regulated mechanisms affect the ability of a fungal pathogen to infect and colonize tobacco leaves
Authors: Hugot Karine , Aimé Sébastien , Conrod Sandrine , Poupet Alain , Galiana Eric 
Published: March 2003

SummaryDuring tobacco development, a transition state from susceptibility to resistance to fungal pathogen infection is observed. Leaves acquire resistance toPhytophthora parasisticawhen the plant becomes committed to flowering. The ability to develop resistance does not imply pathogen‐induced defence responses as for the onset of systemic acquired resistance (SAR). Throughout flowering growth, fungal establishment is restrained at two levels. The first level is the control of infection effectiveness. Using the salicylic acid non‐accumulating NahG plants, we demonstrate that this control does not require salicylic acid accumulation. The intercellular fluids (IFs) from tobacco leaves committed to flowering exhibit a cytotoxic activity on fungal zoospore cells based onin vitrogermination assays. Its accumulation is correlated to the control of infection effectiveness that occurs during flowering growth. The expression of this activity appears to constitute a developmental regulated mechanism that inhibits early steps of fungal pathogen installation. A second level of fungal growth control is the restriction of fungal hyphae expansion. In contrast to infection initiation, fungal hyphae spreading appears to be restricted by similar mechanisms induced during SAR as it is attested by the requirement of salicylic acid accumulation and by the correlating apoplastic accumulation of PR1 proteins. These results provide evidence for the activation of a set of at least two regulatory pathways during flowering growth. This activation leads to the induction of mechanisms which control fungal development by affecting the ability of the fungus to both infect and colonise plant tissues.