bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental expression and biochemical analysis of the Arabidopsis atao1 gene encoding an H2O2‐generating diamine oxidase
Authors: Møller Simon G. , McPherson Michael J. 
Published: March 2003

SummaryA copper amine oxidase encoding gene, atao1, has been isolated and characterized from Arabidopsis thaliana. Sequence analysis reveals that atao1 encodes a 668 amino acid polypeptide (ATAO1) with 48% identity to copper amine oxidases from pea and lentil. The promoter region of atao1 was transcriptionally fused with the reporter genes encoding β‐glucuronidase and modified green fluorescent protein. Analysis of transgenic Arabidopsis together with in situ hybridization of wild‐type plants reveals temporally and spatially discrete patterns of gene expression in lateral root cap cells, vascular tissue of roots, developing leaves, the hypocotyl, and in the style/stigmatal tissue. Enzyme activity assays show that ATAO1 preferentially oxidizes the aliphatic diamine putrescine with production of the corresponding aldehyde, ammonia and hydrogen peroxide, a recognized plant signal molecule and substrate for peroxidases. Histochemical analysis reveals that atao1 expression in developing tracheary elements precedes and overlaps with lignification and therefore is a good marker for vascular development. In both vascular tissue and the root cap, atao1 expression occurs in cells destined to undergo programmed cell death.
Summary
Authors: Baunsgaard Lone , Fuglsang Anja T. , Jahn Thomas , Korthout Henrie A. A. J. , De Boer Albertus H. , Palmgren Michael G. 
Published: March 2003

SummaryThe plasma membrane H+‐ATPase in higher plants has been implicated in nutrient uptake, phloem loading, elongation growth and establishment of turgor. Although a C‐terminal regulatory domain has been identified, little is known about the physiological factors involved in controlling the activity of the enzyme. To identify components which play a role in the regulation of the plant H+‐ATPase, a fusicoccin responsive yeast expressing Arabidopsis plasma membrane H+‐ATPase AHA2 was employed. By testing the fusicoccin binding activity of yeast membranes, the C‐terminal regulatory domain of AHA2 was found to be part of a functional fusicoccin receptor, a component of which was the 14–3‐3 protein. ATP hydrolytic activity of AHA2 expressed in yeast internal membranes was activated by all tested isoforms of the 14–3‐3 protein of yeast and Arabidopsis, but only in the presence of fusicoccin, and activation was prevented by a phosphoserine peptide representing a known 14–3‐3 protein binding motif in Raf‐1. The results demonstrate that the 14–3‐3 protein is an activator molecule of the H+‐ATPase and provides the first evidence of a protein involved in activation of plant plasma membrane H+‐ATPase.
Phage display selection can differentiate insecticidal activity of soybean cystatins
Authors: Koiwa Hisashi , Shade Richard E. , Zhu‐Salzman Keyan , Subramanian Lalitha , Murdock Larry L. , Nielsen S. Suzanne , Bressan Ray A. , Hasegawa Paul M. 
Published: March 2003

SummaryPlant cysteine proteinase inhibitors (phytocystatins) have been implicated as defensive molecules against Coleopteran and Hemipteran insect pests. Two soybean cystatins, soyacystatin N (scN) and soyacystatin L (scL), have 70% sequence identity but scN is a much more potent inhibitor of papain, vicilin peptidohydrolase and insect gut proteinases. When these cystatins were displayed on phage particles, papain‐binding affinity and CPI activity of scN were substantially greater than those of scL, in direct correlation with their relative CPI activity as soluble recombinant proteins. Furthermore, scN substantially delayed cowpea weevil (Callosobruchus maculatus (F.)) growth and development in insect feeding bioassays, whereas scL was essentially inactive as an insecticide. Papain biopanning selection of phage‐displayed soyacystatins resulted in a 200–1000‐fold greater enrichment for scN relative to scL. These results establish that binding affinity of cystatins can be used in phage display biopanning procedures to select variants with greater insecticidal activity, illustrating the potential of phage display and biopanning selection for directed molecular evolution of biological activity of these plant defensive proteins.
A naturally occurring functional allele of the rice waxy locus has a GT to TT mutation at the 5′ splice site of the first intron
Authors: Isshiki Masayuki , Morino Kazuko , Nakajima Midori , Okagaki Ron J. , Wessler Susan R. , Izawa Takeshi , Shimamoto Ko 
Published: March 2003

SummaryIn cultivated rice two wild‐type alleles, Wxa and Wxb, predominate at the waxy locus, which encodes granule‐bound starch synthase. The activity of Wxa is 10‐fold higher than that of Wxb at the level of both protein and mRNA.Wxb has a +1G to T mutation at the 5′ splice site of the first intron. Sequence analysis of Wxb transcripts revealed that splicing occurs at the mutant AG/UU site and at two cryptic sites: the first is A/GUU, one base upstream of the original site and the second is AG/GU found approximately 100 bases upstream of the mutant splice site. We introduced single base mutations to the 5′ splice sites of both Wxa and Wxb, fused with the gus reporter gene and introduced them into rice protoplasts. Analysis of GUS activities and transcripts indicated that a G to T mutation in Wxa reduced GUS activity and the level of spliced RNA. Conversely, a T to G mutation of Wxb restored GUS activity and the level of spliced RNA to that of wild‐type Wxa. These results demonstrated that the low level expression of Wxb results from a single base mutation at the 5′ splice site of the first intron. It is of interest that the Wxb allele of rice carrying the G to T mutation of intron 1 has been conserved in the history of rice cultivation because there is a low amylose content of the seed caused by this mutation.
FLD interacts with genes that affect different developmental phase transitions to regulate Arabidopsis shoot development
Authors: Chou Ming‐Lun , Yang Chang‐Hsien 
Published: March 2003

SummaryA new fld mutant allele, fld‐2, which significantly delayed flowering, was isolated and characterized in Arabidopsis thaliana. Even under long‐day conditions after more than 100 days in the greenhouse, the majority of fld‐2 mutant plants had not bolted. In addition, mutant inflorescences produced more than 10 co‐florescences that were subtended by a high number of rosette‐like leaves before giving rise to flowers. The late‐flowering phenotype of the fld‐2 mutation could be partially overcome by both vernalization and GA treatment but it was not influenced by 5‐azaC treatment. Phenotypic analyses of double mutants indicated that fld‐2 is epistatic to early flowering mutants elf1, elf2 and elf3. In addition, fld‐2 could enhance vegetative characteristics in embryonic flower 1 (emf1) mutants by causing many small sessile leaves in fld‐2 emf1 double mutants. The relief of the terminal flower 1 (tfl1) mutant phenotype in fld‐2 tfl1 double mutants, and the enhancement of leafy (lfy) and apetala1 (ap1) mutant phenotypes in fld‐2 lfy and fld‐2 ap1 double mutants, suggest that FLD is also likely to be involved in the floral transition. Our results strongly suggest that the FLD gene plays a key role in regulating the reproductive competence of the shoot and results in different developmental phase transitions in Arabidopsis.
Cloning of the fructan biosynthesis pathway of Jerusalem artichoke
Authors: Van Der Meer Ingrid M. , Koops Andries J. , Hakkert Johanna C. , Van Tunen Arjen J. 
Published: March 2003

Summary To study the regulation of fructan synthesis in plants, we isolated two full‐size cDNA clones encoding the two enzymes responsible for fructan biosynthesis in Jerusalem artichoke (

Helianthus tuberosus

): 1‐sucrose:sucrose fructosyl transferase (1‐SST) and 1‐fructan:fructan fructosyl transferase (1‐FFT). Both enzymes have recently been purified to homogeneity from Jerusalem artichoke tubers (Koops and Jonker (1994)

J. Exp. Bot.

45, 1623–1631; Koops and Jonker (1996)

Plant Physiol.

110, 1167–1175) and their amino acid sequences have been partially determined. Using RT–PCR and primers based on these sequences, specific fragments of the genes were amplified from tubers of Jerusalem artichoke. These fragments were used as probes to isolate the cDNAs encoding 1‐SST and 1‐FFT from a tuber‐specific λZAP library. The deduced amino acid sequences of both cDNAs perfectly matched the sequences of the corresponding purified proteins. At the amino acid level, the cDNA sequences showed 61% homology to each other and 59% homology to tomato vacuolar invertase. Based on characteristics of the deduced amino acid sequence, the first 150 bp of both genes encode a putative vacuolar targeting signal. Southern blot hybridization revealed that both 1‐SST and 1‐FFT are likely to be encoded by single‐copy genes. Expression studies based on RNA blot analysis showed organ‐specific and developmental expression of both genes in growing tubers. Lower expression was detected in flowers and in stem. In other organs, including leaf, roots and dormant tubers, no expression could be detected. In tubers, the spatial and developmental expression correlates with the accumulation of fructans. Using the

1‐sst

and

1‐fft

cDNAs, chimeric genes were constructed driven by the CaMV 35S promoter. Analysis of transgenic petunia plants carrying these constructs showed that both cDNAs encode functional fructosyltransferase enzymes. Plants transformed with the 35S‐

1‐sst

construct accumulated the oligofructans 1‐kestose (GF2), 1,1‐nystose (GF3) and 1,1,1‐fructosylnystose (GF4). Plants transformed with the 35S‐

1‐fft

construct did not accumulate fructans, probably because of the absence of suitable substrates for 1‐FFT, i.e. fructans with a degree of polymerization ≥ 3 (GF2, GF3, etc.). Nevertheless, protein extracts from these transgenic plants were able to convert GF3, when added as a substrate, into fructans with a higher degree of polymerization. Progeny of crosses between a 35S‐

1‐sst

‐containing plant and a 35S‐

1‐fft‐

containing plant, showed accumulation of high‐molecular‐weight fructans in old, senescent leaves. Based on the comparison of the predicted amino acid sequences of

1‐sst

and

1‐fft

with those of other plant fructosyl transferase genes, we postulate that both plant fructan genes have evolved from plant invertase genes.
Multiple photoreceptors mediate the light‐induced reduction of GUS‐COP1 from Arabidopsis hypocotyl nuclei
Authors: Osterlund Mark T. , Deng Xing‐Wang 
Published: March 2003

Summary The subcellular localization of COP1, a key photomorphogenic repressor, is regulated by light in Arabidopsis seedlings. Photoreceptor loss‐of‐function mutants and dominant gain‐of‐function overexpression transgenes were both used to analyze the influences of the three photoreceptors, phyA, phyB, and CRY1, on the light‐regulated subcellular localization of COP1. Through a semiquantitative analysis of the nuclear abundance of GUS‐COP1 in the various genetic backgrounds, the specific roles of the individual photoreceptors have been established. The data suggest that multiple photoreceptors influence the light‐regulated subcellular localization of COP1 in white light. Under specific wavelengths of light, phyA, phyB, and CRY1 each play critical roles in mediating far‐red, red, and blue light signals, respectively. Our data also support an interdependency between CRY1 and the phytochromes in mediating the light‐regulated subcellular localization of COP1 and thus seedling development.
Quantitative analysis of the local rates of growth of dicot leaves at a high temporal and spatial resolution, using image sequence analysis
Authors: Schmundt Dominik , Stitt Mark , Jähne Bernd , Schurr Ulrich 
Published: March 2003

Summary A new technique is presented for quantitative mapping of dicot leaf growth at high spatial and temporal resolution, at a speed making online‐mapping feasible. Time lapse video sequences of growing leaves are captured by a personal computer (PC) with a frame‐grabber board and a standard CCD camera, and evaluated using algorithms that have been recently developed to analyse motion in dynamic image sequences. Growth can be detected at under 1% per hour, with a time resolution of minutes and a spatial resolution of a few millimeters. The new technique has been verified by comparing it with classical approaches to map integrated growth. Diurnal courses of leaf growth of

Ricinus communis

and tobacco are presented to demonstrate the localised character of growth in leaves. Expansion growth is restricted to the base of the leaf and is restricted to a few hours at the end of the night and the start of the day. The high resolution of the method is illustrated by mapping the responses to step‐changes in leaf turgor. A 3 bar turgor jump led to a rapid transient expansion over the entire length of the leaf that was partially reversed when the turgor was relaxed.
Lesion mimic mutants of rice with alterations in early signaling events of defense
Authors: Takahashi Akira , Kawasaki Tsutomu , Henmi Kenji , Shii Katsuhiko , Kodama Osamu , Satoh Hikaru , Shimamoto Ko 
Published: March 2003

Summary We screened 93 lesion mimic mutants of rice for resistance to the blast fungus,
Magnaporthe grisea
, and found eight mutants that exhibited significant resistance to the fungus. We called these mutants
cdr
(cell death and resistance) and further analyzed three of them. Two mutations,
cdr1
and
cdr2
, were recessive and one,
Cdr3
, was dominant. Many small brownish lesions developed over the entire leaf of the mutants 20–50 days after sowing. TUNEL staining revealed that DNA fragmentation occurred in leaf blade cells of the homozygous
Cdr3
mutants. Autofluorescence and callose deposition were visible in leaf cells of these three mutants. Activation of two defense‐related genes,
PBZ1
and
PR1
, was observed in the leaves of the mutants; high expression of
PBZ1
was correlated with the lesion formation in the three mutants, whereas
PR1
was constitutively expressed in the
cdr2
and
Cdr3
mutants irrespective of the lesion formation. Levels of momilactone A, a major phytoalexin of rice, in these mutants were increased approximately 100–400‐fold relative to the wild‐type levels. Suspension‐cultured cells of the
cdr1
and
cdr2
but not
Cdr3
produced higher levels of H2O2 than the wild type when treated with calyculin A, an inhibitor of protein phosphatase 1. These results suggest that biochemical lesions of
cdr1
and
cdr2
lie in the early signaling steps leading to activation of the NADPH oxidase and that type‐1 protein phosphatase is operative in protein dephosphorylation involved in NADPH oxidase activation.
Developmental stage‐specific multi‐subunit plastid RNA polymerases (PEP) in wheat
Authors: Satoh Junko , Baba Kyoko , Nakahira Yoichi , Tsunoyama Yuichi , Shiina Takashi , Toyoshima Yoshinori 
Published: March 2003

SummaryMost photosystem I and II plastid genes are transcribed by a plastid encoded Escherichia coli‐like RNA polymerase (PEP). In this study, we show that both promoter selectivity and light‐dependency of PEP change dramatically during development in wheat leaves. In the leaf tip, psbA and psbD promoter activities are light induced, whilst psbC, psbE and 16S rRNA promoters do not function efficiently irrespective of light conditions. In contrast to the leaf tip, in the basal portion all PEP promoters studied function in the dark as well as the light, except for psbD. Using in vitro transcription, we found that PEP in the illuminated leaf tip can initiate transcription from the –35 destructed psbA promoter, but the –35 element is essential for transcription in the basal portion. There is an extended –10 element in the psbA promoter, recognized by the PEP in the illuminated leaf tip or purified σ70‐type Escherichia coli RNA polymerase but not by the PEP in the leaf base. These results suggest that during wheat leaf development, PEP in the leaf base that is functional for most PEP promoters even in the dark is replaced by the light‐dependent PEP selectively transcribing the psbA and psbD promoters.
Phosphorylation of pea chloroplast acetyl‐CoA carboxylase
Authors: Savage Linda J. , Ohlrogge John B. 
Published: March 2003

SummaryWe have examined whether chloroplast acetyl‐CoA carboxylase is a phosphoprotein. Pea (Pisum sativum) chloroplasts were incubated in the presence of [γ‐33P]‐ATP and radiolabeled proteins were examined after immunoprecipitation with antibodies against all four known subunits of heteromeric chloroplast acetyl‐CoA carboxylase. The β‐subunit of the carboxyltransferase was found to be labeled by33P. Phosphoamino acid analysis of the immunoprecipitated β‐subunit of the carboxyltransferase indicates that it is phosphorylated on serine residues. Incorporation of33P into carboxyltransferase β‐subunit decreased in chloroplasts transferred to dark conditions after labeling in the light. Dephosphorylation of pea chloroplast extracts by an alkaline phosphatase‐agarose conjugate reducedin vitroacetyl‐CoA carboxylase activity by 67%. Furthermore, while acetyl‐CoA carboxylase activity and its carboxyltransferase half‐reaction were reduced in dephosphorylated extracts, the biotin carboxylase half‐reaction was not inhibited. The evidence presented here points to the carboxyltransferase β‐subunit of chloroplast acetyl‐CoA carboxylase as a candidate for regulation by protein phosphorylation/dephosphorylation.
Structural and functional analysis of the six regulatory particle triple‐A ATPase subunits from the Arabidopsis 26S proteasome
Authors: Fu Hongyong , Doelling Jed H. , Rubin David M. , Vierstra Richard D. 
Published: March 2003

Summary The 26S proteasome is a multi‐subunit ATP‐dependent protease responsible for degrading most short‐lived intracellular proteins targeted for breakdown by ubiquitin conjugation. The complex is composed of two relatively stable subparticles, the 20S proteasome, a hollow cylin‐ drical structure which contains the proteolytic active sites in its lumen, and the 19S regulatory particle (RP) which binds to either end of the cylinder and provides the ATP‐dependence and the specificity for ubiquitinated proteins. Among the approximately 18 subunits of the RP from yeast and animals are a set of six proteins, desig‐ nated RPT1–6 for regulatory particle triple‐A ATPase, that form a distinct family within the AAA superfamily. Presumably, these subunits use ATP hydrolysis to help assemble the 26S holocomplex, recognize and unfold appropriate substrates, and/or translocate the substrates to the 20S complex for degradation. Here, we describe the RPT gene family from Arabidopsis thaliana. From a collection of cDNAs and genomic sequences, a family of genes encoding all six of the RPT subunits was identified with significant amino acid sequence similarity to their yeast and animal counterparts. Five of the six RPT sub‐ units are encoded by two genes; the exception being RPT3 which is encoded by a single gene. mRNA for each of the six proteins is present in all tissue types examined. Five of the subunits (RPT1 and 3–6) complemented yeast mutants missing their respective orthologs, indicating that the yeast and Arabidopsis proteins are functionally equivalent. Taken together, these results demonstrate that the RP, like the 20S proteasome, is functionally and structurally conserved among eukaryotes and indicate that the plant RPT subunits, like their yeast counterparts, have non‐redundant functions.
Molecular and functional regulation of two NO3– uptake systems by N‐ and C‐status of Arabidopsis plants
Authors: Lejay Laurence , Tillard Pascal , Lepetit Marc , Olive Francesc Domingo , Filleur Sophie , Daniel‐Vedele Françoise , Gojon Alain 
Published: March 2003

Summary Root NO

3

–

uptake and expression of two root NO

3

–

transporter genes (

Nrt2;1

and Nrt1) were investigated in response to changes in the N‐ or C‐status of hydroponically grown Arabidopsis thaliana plants. Expression of Nrt2;1 is up‐regulated by NO

3

–

starvation in wild‐type plants and by N‐limitation in a nitrate reductase (NR) deficient mutant transferred to NO

3

–

as sole N source. These observations show that expression of Nrt2;1 is under feedback repression by N‐metabolites resulting from NO

3

–

reduction. Expression of Nrt1 is not subject to such a repression. However, Nrt1 is over‐expressed in the NR mutant even under N‐sufficient conditions (growth on NH

4

NO

3

medium), suggesting that expression of this gene is affected by the presence of active NR, but not by N‐status of the plant. Root

15

NO

3

–

influx is markedly increased in the NR mutant as compared to the wild‐type. Nevertheless, both genotypes have similar net

15

NO

3

–

uptake rates due to a much larger

14

NO

3

–

efflux in the mutant than in the wild‐type. Expressions of Nrt2;1 and Nrt1 are diurnally regulated in photosynthetically active A. thaliana plants. Both increase during the light period and decrease in the first hours of the dark period. Sucrose supply prevents the inhibition of Nrt2;1 and Nrt1 expressions in the dark. In all conditions investigated, Nrt2;1 expression is strongly correlated with root

15

NO

3

–

influx at 0.2 m

m

external concentration. In contrast, changes in the Nrt1 mRNA level are not always associated with similar changes in the activities of high‐ or low‐affinity NO

3

–

transport systems.
Hormonal regulation of a cysteine proteinase gene, EPB‐1, in barley aleurone layers: cis‐ and trans‐acting elements involved in the co‐ordinated gene expression regulated by gibberellins and abscisic acid
Authors: Cercós Manuel , Gómez‐Cadenas Aurelio , Ho Tuan‐Hua David 
Published: March 2003

SummaryThe synthesis of EPB, a cysteine proteinase responsible for the degradation of seed endosperm storage proteins in barley (Hordeum vulgare), is induced by gibberellins (GA) and repressed by abscisic acid (ABA). The EPB gene family consists of two very similar members, EPB‐1 and EPB‐2, with the former being more highly induced by GA. We have functionally characterized the cis‐acting elements in the EPB‐1 promoter and determined that a gibberellin response element (GARE), a pyrimidine box and an upstream element are necessary for GA induction. By comparison with the promoters of α‐amylase genes, which are also induced by GA, we suggest that GARE is coupled with the upstream element and the pyrimidine box to form a GA response complex. In addition, we have shown that the 3′‐untranslated/untranscribed region of the EPB‐1 gene is required for a low background expression in the absence of GA. Constitutive expression of a transcription factor, GAMyb, in the absence of GA leads to the transactivation of EPB‐1 expression in a dosage dependent manner with the highest level comparable to that in fully GA‐induced tissue. Co‐expression of a truncated version of GAMyb containing only the DNA binding domain blocks the GA‐induction of EPB‐1, further supporting the role of GAMyb in the regulation of gene expression. Although ABA is very effective in blocking the GA induction of EPB‐1, it has no effect on the GAMyb‐mediated expression of EPB‐1. We suggest that ABA acts upstream of the formation of functional GAMyb which co‐ordinates the hormonal regulation of a diverse group of genes in cereal aleurone layers, including those encoding EPB and α‐amylases.