bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular cloning of a carotenoid‐associated protein from Cucumis sativus corollas: homologous genes involved in carotenoid sequestration in chromoplasts
Authors: Vishnevetsky Michael , Ovadis Marianna , Itzhaki Hanan , Levy Maggie , Libal‐Weksler Yael , Adam Zach , Vainstein Alexander 
Published: March 2003

SummaryChromoplasts are carotenoid‐accumulating plastids found in the corollas and fruits of many higher plants. In most cases, the pigment in these plastids is accumulated with the aid of carotenoid‐associated proteins located within unique structures. This paper reports the isolation and characterization of the cDNA (CHRC) from Cucumis sativus corollas which encodes the chromoplast‐specific carotenoid‐associated protein CHRC. The transit peptide cleavage site was determined and, using a chloroplast uptake system, it is shown that CHRC can be post‐translationally targeted to these plastids where it is peripherally associated with thylakoids. Analysis of CHRC transcript level in Cucumis sativus revealed its temporal and tissue‐specific regulation: the transcript was detected only in corollas, where its level increased in parallel to flower development, peaking just before anthesis. CHRC shares significant homology (59%) with the gene coding for fibrillin — a protein in Capsicum annuum red fruits whose function is essentially identical to that of CHRC. A CHRC fragment including the potential active site of the protein was used as a probe in Northern blot analyses of floral and fruit tissues from various plants containing chromoplasts of different types: CHRC homologs of similar sizes were revealed in all cases. The existence of a group of homologous genes coding for chromoplast‐specific proteins which aid in the sequestration of carotenoids within specific structures is proposed.
Phloem‐specific expression of a plant homeobox gene during secondary phases of vascular development
Authors: Tornero Pablo , Conejero Vicente , Vera Pablo 
Published: March 2003

SummaryThis paper reports the isolation and characterization of a homeobox gene (VAHOX1) from Lycopersicon esculentum encoding a homeodomain protein that contains a leucine zipper motif. The bipartite homeodomain‐leucine zipper (HD‐Zip) motif has only been found in homeobox genes from dicotyledonous plants, indicating that this type of transcription factor regulates particular developmental processes in these plant species. Here, the genomic organization, sequence comparison and expression analysis of VAHOX1 are described. Transcriptional fusion of the 5′ promoter region of VAHOX1 with the reporter GUS gene (VAHOX1—GUS) and expression analysis of this construct in transgenic plants indicates that VAHOX1 is specifically expressed in the phloem during phases of secondary growth. Unlike other plant homeobox genes, VAHOX1 does not appear to be expressed in meristems, and the function of VAHOX1 is considered a likely candidate molecule that may participate in the regulation of the identity and/or activity of phloem tissues during secondary phases of vascular development.
Transgenic tobacco plants expressing the Arabidopsis thaliana nitrilase II enzyme
Authors: Schmidt Ralf‐C. , Müller Axel , Hain Rüdiger , Bartling Dieter , Weiler Elmar W. 
Published: March 2003

SummaryNitrilase (E.C. 3.5.5.1) cloned from Arabidopsis thaliana converts indole‐3‐acetonitrile to the plant growth hormone, indole‐3‐acetic acid in vitro. To probe the capacity of this enzyme under physiological conditions in vivo, the cDNA PM255, encoding nitrilase II, was stably integrated into the genome of Nicotiana tabacum by direct protoplast transformation under the control of the CaMV‐35S promotor. The regenerated plants appeared phenotypically normal. Nitrilase II was expressed, based on the occurrence of its mRNA and polypeptide. The enzyme was catalytically active, when extracted from leaf tissue of transgenic plants (specific activity: 25 fkat mg−1 protein with indole3‐acetonitrile as substrate). This level of activity was lower than that found in A. thaliana, and this was deemed essential for the in vivo analysis. Leaf tissue from the transgenic plants converted 1‐[13C]‐indole‐3‐acetonitrile to 1‐[13C]‐indole‐3‐acetic acid in vivo as determined by HPLC/ GC‐MS analysis. Untransformed tobacco was unable to catalyze this reaction. When transgenic seeds were grown on medium in the absence of indole‐3‐acetonitrile, germination and seedling growth appeared normal. In the presence of micromolar levels of exogenous indole‐3‐acetonitrile, a strong auxin‐overproducing phenotype developed resulting in increased lateral root formation (at 10 µM indole‐3‐acetonitrile) or stunted shoot growth, excessive lateral root initiation, inhibition of root out‐growth and callus formation at the root/shoot interface (at 100 µM indole‐3‐acetonitrile). Collectively, these data prove the ability of nitrilase II to convert low micromolar levels of indole‐3‐acetonitrile to indole‐3‐acetic acid in vivo, even when expressed at subphysiological levels thereby conferring a high‐auxin phenotype upon transgenic plants. Thus, the A. thaliana nitrilase activity, which exceeds that of the transgenic plants, would be sufficient to meet the requirements for auxin biosynthesis in vivo.
Transcriptional activation of a maize α‐tubulin gene in mycorrhizal maize and transgenic tobacco plants
Authors: Bonfante Paola , Bergero Roberta , Uribe Xavier , Romera Carme , Rigau Joan , Puigdomenech Pere 
Published: March 2003

SummaryMycorrhizae are symbioses between soil fungi and roots, with substantial modifications of the cells of both partners. Thus, host cells colonized by mycorrhizal fungi may express otherwise inactive genes. Here it is demonstrated that two arbuscular mycorrhizal (AM) fungi, Glomus versiforme and Gigaspora margarita, cause the transcriptional activation of a gene coding for α‐tubulin in the colonized cells of maize and transgenic tobacco roots. Tobacco plants transformed with a construct containing the maize Tubα3 gene promoter fused upstream from the bacterial GUS gene showed an intense GUS activity only in meristematic regions. When colonized by G. margarita, GUS activity was detected in the cortical root cells containing fungal arbuscules. No GUS activity was found in root cells when transformants carrying Tubα1 promoter were used, nor when Tubα3 transformants were colonized by ericoid mycorrhizal fungi, leading to a non‐specific interaction. Activation of the Tubα3 appears to be specific to the gene and to the appropriate interaction. Further evidence that fully differentiated host tissues re‐activate the Tubα3 gene following colonization by AM fungi also comes from accumulation of the corresponding transcripts in maize root cells containing arbuscules.
Visualization of differential gene expression using a novel method of RNA fingerprinting based on AFLP: Analysis of gene expression during potato tuber development
Authors: Bachem Christian W.B. , Van Der Hoeven Rutger S. , De Bruijn Steef M. , Vreugdenhil Dick , Zabeau Marc , Visser Richard G.F. 
Published: March 2003

SummaryUsing a highly synchronous in vitro tuberization system, in combination with an amplified restriction fragment polymorphism (AFLP†)‐derived technique for RNA fingerprinting (cDNA‐AFLP‡), transcriptional changes at and around the time point of potato tuberization have been analyzed. The targeted expression analysis of a specific transcript coding for the major potato storage protein, patatin and a second transcript, coding for ADP‐glucose pyrophosphorylase, a key gene in the starch biosynthetic pathway is described. This paper confirms that kinetics of expression revealed by cDNA‐AFLP analysis are comparable to those found in Northern analysis. Furthermore, this paper reports the isolation and analysis of two tuberspecific transcript‐derived fragments (TDFs) coding for the lipoxygenase enzyme, which are differentially induced around the time point of tuber formation. Analysis of the two lox TDFs demonstrates that it is possible to dissect the expression modalities of individual transcripts, not independently detectable by Northern analysis. Finally, it is shown that using cDNA‐AFLP, rapid and simple verification of band identity may be achieved. The results indicate that cDNA‐AFLP is a broadly applicable technology for identifying developmentally regulated genes.
Induction of 1‐aminocyclopropane‐1‐carboxylate oxidase mRNA by ethylene in mung bean hypocotyls: involvement of both protein phosphorylation and dephosphorylation in ethylene signaling
Authors: Kim Jeong Hoe , Kim Woo Taek , Kang Bin G. , Yang Shang Fa 
Published: March 2003

SummaryEthylene induced an increase in the level of 1‐aminocyclopropane‐1‐carboxylate (ACC) oxidase mRNA but suppressed the expression of ACC synthase transcript in mung bean hypocotyls. Induction of ACC oxidase transcript by ethylene was saturated at a low concentration (1–3 µl l−1) and detectable within 1 h after ethylene treatment; 2,5‐norbornadiene, an inhibitor of ethylene action, significantly reduced the basal level of ACC oxidase transcript present in intact mung bean hypocotyls. Treatment with the protein synthesis inhibitor cycloheximide completely inhibited the ethylene‐induced accumulation of ACC oxidase transcript, indicating that de novo protein synthesis is necessary for expression of the ethylene‐inducible ACC oxidase gene. ABA decreased the ethylene‐induced accumulation of ACC oxidase mRNA, but restored the ethylene‐suppressed level of ACC synthase (VR‐ACS1) transcript. The protein kinase inhibitor staurosporine effectively prevented ethylene‐induced ACC oxidase gene expression, whereas it substantially recovered the ethylene‐suppressed transcript level of ACC synthase, suggesting that protein phosphorylation plays a role in the induction of ACC oxidase and the suppression of ACC synthase by ethylene in mung bean hypocotyls. Okadaic acid, a potent inhibitor of protein phosphatase, did not affect the expression of ACC oxidase. However, addition of okadaic acid along with ethylene effectively blocked the ethylene‐induced accumulation of ACC oxidase transcript, while there was an increase in the level of ethylene‐suppressed ACC synthase transcript. These results indicate that protein dephosphorylation in addition to phosphorylation is necessary for the ethylene signaling that regulates the expression of these genes.
Transfer RNA‐mediated suppression of amber stop codons in transgenic Arabidopsis thaliana
Authors: Betzner Andreas S. , Oakes Marie P. , Huttner Eric 
Published: March 2003

SummaryAn artificial amber suppressor tRNALeu gene (supL.) was physically linked to a mutated gus reporter gene, p35S‐gus(amL), which was inactivated by an amber stop codon (amL). Upon introduction into Arabidopsis thaliana, the presence of the supL. gene was found to be correlated with cytotoxic effects observed during tissue culture and in mature plants. Those primary transformants that displayed cytotoxic symptoms were shown by X‐Gluc staining to express GUS as a result of amber stop codon suppression in vivo. Phenotypically normal lines were found by RT‐PCR to express supL. GUS activity above background level was barely detectable in these plants, indicating a low level expression of supL. However, the remaining suppressor activity was still sufficient to transactivate an amber‐mutated male sterility gene, pA9‐barnase(amL1) when combined within the same plant by crossing. The suppressor tRNALeu gene may thus be used in transgenic plants for gene transactivation.
Use of Arabidopsis recombinant inbred lines reveals a monogenic and a novel digenic resistance mechanism to Xanthomonas campestris pv campestris
Authors: Buell C.R. , Somerville S.C. 
Published: March 2003

SummaryInfiltration of the Arabidopsis thaliana accession Landsberg erecta (Ler) with Xanthomonas campestris pv campestris isolate 2D520 results in extensive necrosis and limited chlorosis within 5–6 days post‐inoculation (d.p.i.), which can lead to systemic necrosis within 23 d.p.i. In contrast, the accession Columbia (Col) remains asymptomatic after infiltration. Although both accessions support bacterial growth, 5–28‐fold more bacteria are present in Ler than in Col leaf tissue. Inheritance studies indicate that three independent, dominant or partially dominant, nuclear genes condition resistance to X. c. campestris 2D520. The major gene, termed RXC2, conditions monogenic resistance to X. c. campestris and was mapped to a 5.5 cM interval of chromosome V. Segregation data indicate that the locus RXC3 in conjunction with RXC4 confers digenic resistance to X. c. campestris. The combined action of RXC3 and RXC4 is correlated with a suppression of in planta bacterial levels and a suppression of symptoms relative to Ler. The RXC3 + RXC4‐mediated resistance is novel in that although the Col allele of RXC4 contributes positively to resistance, it is the Ler and not the Col allele of RXC3 that contributes positively to resistance. RXC3 was mapped to the bottom arm of chromosome V in a 2.7 cM interval within the major recognition gene complex MRC‐J, a cluster of genes involved in disease resistance. RXC4 was mapped to a 12 cM interval on chromosome II that also contains RXC1, a gene conferring tolerance to X. c. campestris.
Interaction of the maize and Arabidopsis kinase interaction domains with a subset of receptor‐like protein kinases: implications for transmembrane signaling in plants
Authors: Braun David M. , Stone Julie M. , Walker John C. 
Published: March 2003

SummaryThe kinase interaction (KI) domain of kinase‐associated protein phosphatase (KAPP) interacts with the phosphorylated form of an Arabidopsis thaliana receptor‐like protein kinase (RLK). The KI domain may recruit KAPP into an RLK‐initiated signaling complex. To examine additional roles that this domain may play in plant signal transduction, a search was conducted for other KI domain‐containing proteins. One gene was isolated which encodes a KI domain, the maize homolog of KAPP. To test whether the maize KI domain associates with other maize proteins, it was used as a probe in a protein–protein interaction cloning strategy. A new maize RLK, KI domain interacting kinase 1 (KIK1), was identified by its interaction with the maize KI domain. The maize KI domain and the KIK1 kinase domain association required phosphorylation of the kinase. This work establishes that the KI domain phosphorylation‐dependent signaling mechanism is present in both monocots and dicots. Additionally, it was determined that both the maize and Arabidopsis KI domains interact with several but not all of the active RLKs assayed. These multiple associations imply that KAPP may function in a number of RLK‐initiated signaling pathways.
Structure and subcellular localization of a small RNA‐binding protein from tobacco
Authors: Moriguchi Kazuki , Sugita Mamoru , Sugiura Masahiro 
Published: March 2003

SummaryIn this study, a cDNA encoding a small RNA‐binding protein was isolated from a Nicotiana sylvestris cDNA library. The predicted protein (RGP‐3) is 144 amino acid residues long, and contains a consensus sequence‐type RNA binding domain (CS‐RBD) of 83 amino acids and a short glycine‐rich region of 15 amino acids. RGP‐3 synthesized in Escherichia coli has high affinity for poly(U). Immunocytochemical analysis indicated that RGP‐3 is localized in the nucleoplasm, and that RGP‐1b, a related protein reported previously, is localized in the nucleolus. Possible roles of these proteins in pre‐mRNA or pre‐rRNA processing are discussed.
ZmEsr, a novel endosperm‐specific gene expressed in a restricted region around the maize embryo
Authors: Opsahl‐Ferstad Hilde‐Gunn , Deunff Erwan Le , Dumas Christian , Rogowsky Peter M. 
Published: March 2003

SummaryA novel endosperm‐specific gene named Esr (embryo surrounding region) has been isolated by differential display between early developmental stages of maize endosperms and embryos. It is expressed in a restricted region of the endosperm, surrounding the entire embryo at early stages (4 to 7 days after pollination, DAP) and ever‐decreasing parts of the suspensor at subsequent stages. The expression starts at 4 DAP and is maintained until at least 28 DAP. A minimum of three Esr genes are present in the maize genome and at least two of them map to the short arm of chromosome 1 at position 56. The Esr genes contain no introns and show no significant nucleotide or amino acid sequence homologies to sequences in the databases. The open reading frames encode basic proteins of 14 kDa with presumptive signal peptides at their N‐termini followed by a hypervariable and a conserved region. The gene product may play a role in the nutrition of the developing embryo or in the establishment of a physical barrier between embryo and endosperm.
High‐efficiency transformation of Arabidopsis thaliana with a selectable marker gene regulated by the T‐DNA 1′ promoter
Authors: Mengiste Tesfaye , Amedeo Paolo , Paszkowski Jerzy 
Published: March 2003

SummaryTwo selectable marker genes harbouring the bar coding region but differing in their promoters were compared in an Arabidopsis thaliana transformation assay using in planta infiltration with Agrobacterium tumefaciens. Surprisingly, in four Arabidopsis ecotypes examined, the 1′ promoter from the right T‐DNA was superior to the most commonly used 35S promoter of cauliflower mosaic virus (CaMV). The ecotype Wassilewskija gave the highest transformation frequencies, with an average of between 5.3 and 6.3 % of the seedlings subjected to the selection. This is approximately 30‐fold higher than previously reported results. Analysis of T‐DNA integration patterns in single transformed plants or pooled populations revealed independent T‐DNA integration events in each case. Results show that the 1′ promoter is an attractive alternative to the 35S promoter for the generation of T‐DNA insertion lines. The 1′ promoter may be especially beneficial for the secondary transformation of transgenic strains containing the 35S promoter to exclude homology‐mediated gene silencing.
An Arabidopsis mutant showing reduced feedback inhibition of photosynthesis
Authors: Van Oosten Jean‐Jacques M. , Gerbaud Alain , Huijser Casper , Dijkwel Paul P. , Chua Nam‐Hai , Smeekens Sjef C.M. 
Published: March 2003

SummaryMany plant genes are responsive to sugars but the mechanisms used by plants to sense sugars are unknown. A genetic approach has been used in Arabidopsis to identify genes involved in perception and transduction of sugar signals. For this purpose, an in vivo reporter system was established consisting of the light‐ and sugar‐regulated plastocyanin promoter, fused to the luciferase coding sequence (PC—LUC construct). At the seedling stage, expression of the PC—LUC gene is repressed by sucrose, and a number of sucrose‐uncoupled (sun) mutants were selected in which sucrose is unable to repress the activity of the PC promoter. Three mutants have been characterized in more detail. The sugar analog 2‐deoxy‐d‐glucose (2DG) was used to repress whole plant photosynthesis, PC—LUC gene expression and total ribulose‐1,5‐bisphosphate activity. It was found that the sun6 mutation makes plants unresponsive to these 2DG‐induced effects. Moreover, unlike wild‐type plants, sun6 mutants are insensitive to elevated levels of glucose in the growth medium. These findings suggest that the SUN6 gene is active in a hexose‐activated signal transduction pathway.
Map positions of 47 Arabidopsis sequences with sequence similarity to disease resistance genes
Authors: Botella Miguel A. , Coleman Mark J. , Hughes Douglas E. , Nishimura Marc T. , Jones Jonathan D.G. , Somerville Shauna C. 
Published: March 2003

SummaryMap positions have been determined for 42 non‐redundant Arabidopsis expressed sequence tags (ESTs) showing similarity to disease resistance genes (R‐ESTs), and for three Pto‐like sequences that were amplified with degenerate primers. Employing a PCR‐based strategy, yeast artificial chromosome (YAC) clones containing the EST sequences were identified. Since many YACs have been mapped, the locations of the R‐ESTs could be inferred from the map positions of the YACs. R‐EST clones that exhibited ambiguous map positions were mapped as either cleavable amplifiable polymorphic sequence (CAPS) or restriction fragment length polymorphism (RFLP) markers using F8 (Ler x Col‐0) recombinant inbred (RI) lines. In all cases but two, the R‐ESTs and Pto‐like sequences mapped to single, unique locations. One R‐EST and one Pto‐like sequence each mapped to two locations. Thus, a total of 47 loci were identified in this study. Several R‐ESTs occur in clusters suggesting that they may have arisen via gene duplication events. Interestingly, several R‐ESTs map to regions containing genetically defined disease resistance genes. Thus, this collection of mapped R‐ESTs may expedite the isolation of disease resistance genes. As the cDNA sequencing projects have identified an estimated 63% of Arabidopsis genes, a very large number of R‐ESTs (∼95), and by inference disease resistance genes of the leucine‐rich repeat‐class probably occur in the Arabidopsis genome.
N‐ and C‐terminal peptide sequences are essential for enzyme assembly, allosteric, and/or catalytic properties of ADP‐glucose pyrophosphorylase
Authors: Laughlin Mary J. , Chantler Sue Ellen , Okita Thomas W. 
Published: March 2003

SummaryADP‐glucose pyrophosphorylase is a key regulatory enzyme in starch synthesis in most plant tissues. Unlike the allosteric regulatory dependent properties of the leaf enzyme, the enzymes from non‐photosynthetic tissues exhibit varying levels of sensitivity to allosteric regulation, a behavior which may be an inherent property of the enzyme or a product of post‐translational modification. As partial proteolysis of the holoenzyme may account for the wide variation of allosteric regulatory behavior exhibited by enzymes from non‐photosynthetic tissues, small N‐ and C‐terminal peptide deletions were made on either the potato large and small subunit and co‐expressed with the counterpart wild‐type subunit in Escherichia coli. Removal of the putative carboxy‐terminal allosteric binding region from either subunit type results in an abolishment of enzyme formation indicating that the carboxy terminus of each subunit type is essential for proper subunit folding and/or enzyme assembly as well as its suggested role in allosteric regulation. Removal of a small 10 amino acid peptide from the N‐terminus of the small subunit increased its resistance to the allosteric inhibitor Pi as well as its sensitivity to heat treatment. Likewise, removal of the corresponding peptide (17 residues) at the N‐terminus of the large subunit also increased its resistance towards Pi inhibition but, in addition, increased its sensitivity to 3‐PGA activation. Deletion of an additional 11 residues reversed these changes in allosteric properties but at the expense of a reduced catalytic turnover rate. Combined, these results indicate that the N‐ and C‐terminal regions are essential for the proper catalytic and allosteric regulatory properties of the potato ADP‐glucose pyrophosphorylase. The possible significance of these results on the observed insensitivity to effector molecules by ADP‐glucose pyrophosphorylases from other non‐photosynthetic tissues is discussed.