bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular characterization of CDSP 34, a chloroplastic protein induced by water deficit inSolanum tuberosumL. plants, and regulation ofCDSP 34expression by ABA and high illumination
Authors: Gillet Benjamin , Beyly Audrey , Peltier Gilles , Rey Pascal 
Published: March 2003

Summary We previously described the accumulation of a 34 kDa thylakoid protein, named CDSP 34 for chloroplastic drought‐induced stress protein, in

Solanum tuberosum

plants subjected to water deficit. A full‐length CDSP 34 cDNA has been isolated and we report here that mature CDSP 34 is highly similar to two chromoplastic proteins, fibrillin from

Capsicum annuum and

CHRC (for chromoplast protein C) from

Cucumis sativus

, components of carotenoid‐accumulating structures. Northern and Western analyses showed that both CDSP 34 transcript and protein accumulated from early stages of water deficit. In water‐stressed tomato plants, similar increases in the CDSP 34‐related transcript amount were noticed in wild‐type and ABA‐deficient

flacca

mutant, but protein accumulation was observed only in wild‐type, suggesting a post‐transcriptional role of ABA in CDSP 34 synthesis regulation. Substantial increases in CDSP 34 transcript and protein abundances were also observed in potato plants subjected to high illumination. The CDSP 34 protein is proposed to play a structural role in stabilizing stromal lamellae thylakoids upon osmotic or oxidative stress.
Auxin and ethylene promote root hair elongation inArabidopsis
Authors: Pitts R. Jason , Cernac Alex , Estelle Mark 
Published: March 2003

Summary Genetic and physiological studies implicate the phytohormones auxin and ethylene in root hair development. To learn more about the role of these compounds, we have examined the root hair phenotype of a number of auxin‐ and ethylene‐related mutants. In a previous study,

Masucci & Schiefelbein (1996

) showed that neither the auxin response mutations

aux1 and axr1

nor the ethylene response mutations

etr1 and ein2

have a significant effect on root hair initiation. In this study, we found that mutants deficient in either auxin or ethylene response have a pronounced effect on root hair length. Treatment of wild‐type,

axr1

and

etr1

seedlings with the synthetic auxin, 2,4‐D, or the ethylene precursor ACC, led to the development of longer root hairs than untreated seedlings. Furthermore,

axr1

seedlings grown in the presence of ACC produce ectopic root hairs and an unusual pattern of long root hairs followed by regions that completely lack root hairs. These studies indicate that both auxin and ethylene are required for normal root hair elongation.
A combined reduction in activity of starch synthases II and III of potato has novel effects on the starch of tubers
Authors: Edwards Anne , Fulton Daniel C.. , Hylton Christopher M.. , Jobling Stephen A.. , Gidley Michael , Rössner Ute , Martin Cathie , Smith Alison M.. 
Published: March 2003

Summary A chimeric antisense construct has been used to generate transgenic potatoes (

Solanum tuberosum

L.) in which activities of both of the main starch synthases responsible for amylopectin synthesis in the tuber (SSII and SSIII) are reduced. The properties of starch from tubers of these plants have been compared with those of starches from transgenic plants in which activity of either SSII or SSIII has been reduced. Starches from the three types of transgenic plant are qualitatively different from each other and from the starch of control plants with unaltered starch synthase activities, with respect to granule morphology, the branch lengths of amylopectin, and the gelatinisation behaviour analysed by viscometry. The effects of reducing SSII and SSIII together cannot be predicted from consideration of the effects of reducing these two isoforms individually. These results indicate that different isoforms of starch synthase make distinct contributions to the synthesis of amylopectin, and that they act in a synergistic manner, rather than independently, during amylopectin synthesis.
Site‐directed mutagenesis of serine 158 demonstrates its role in spinach leaf sucrose‐phosphate synthase modulation
Authors: Toroser Dikran , McMichael Robert , Krause Klause‐Peter , Kurreck Jens , Sonnewald Uwe , Stitt Mark , Huber Steven C. 
Published: March 2003

Summary Site‐directed mutagenesis of spinach sucrose‐phosphate synthase (SPS) was performed to investigate the role of Ser158 in the modulation of spinach leaf SPS. Tobacco plants expressing the spinach wild‐type (WT), S158A, S158T and S157F/S158E SPS transgenes were produced. Expression of transgenes appeared not to reduce expression of the tobacco host SPS. SPS activity in the WT and the S158T SPS transgenics showed light/dark modulation, whereas the S158A and S157F/S158E mutants were not similarly light/dark modulated: the S158A mutant enzyme was not inactivated in the dark, and the S157F/S158E was not activated in the light. The inability to modulate the activity of the S158A mutant enzyme by protein phosphorylation was demonstrated

in vitro

. The WT spinach enzyme immunopurified from dark transgenic tobacco leaves had a low initial activation state, and could be activated by PP2A and subsequently inactivated by SPS‐kinase plus ATP. Rapid purification of the S158A mutant enzyme from dark leaves of transgenic plants using spinach‐specific monoclonal antibodies yielded enzyme that had a high initial activation state, and pre‐incubation with leaf PP2A or ATP plus SPS‐kinase (the PKIII enzyme) caused little modulation of activity. The results demonstrate the regulatory significance of Ser158 as the major site responsible for dark inactivation of spinach SPS

in vivo

, and indicate that the significance of phosphorylation is the introduction of a negative charge at the Ser158 position.
Changes in aldolase activity in wild‐type potato plants are important for acclimation to growth irradiance and carbon dioxide concentration, because plastid aldolase exerts control over the ambient rate of photosynthesis across a range of growth conditions
Authors: Haake Volker , Geiger Michael , Walch‐Liu Pia , Of Engels Christ , Zrenner Rita , Stitt Mark 
Published: March 2003

Summary Even though plastid aldolase catalyses a reversible reaction, does not possess properties allowing it to contribute to ‘fine’ regulation, and would therefore be considered unimportant for the control of metabolism and growth, antisense transformants with a 50–70% decrease in aldolase activity showed an inhibition of photosynthesis and growth. We now show that acclimation of photosynthesis to growth conditions includes and requires changes in plastid aldolase activity. Wild‐type potato plants and transformants were grown at low irradiance (70 μmol m–2 sec–1), and at high irradiance (390 μmol m–2 sec–1) at 400 or 800 p.p.m. carbon dioxide. (i) Ambient photosynthesis was always inhibited by a 30–40% decrease of aldolase activity, the strongest inhibition being observed when plants were growing in high irradiance and elevated carbon dioxide. (ii) The inhibition was due to a low rate of ribulose‐1,5‐bisphosphate regeneration in low light, exacerbated by an inadequate rate of starch synthesis in high light and elevated carbon dioxide. Decreased expression of aldolase in antisense transformants was also accompanied by a decrease of fructose‐1,6‐bisphosphatase protein and activity, and Rubisco activity. Transcript levels for the plastid fructose‐1,6‐bisphosphatase and the small subunit of Rubisco did not decrease. (iii) In wild‐type plants, increasing the growth irradiance from 70 to 390 μmol m–2 sec–1 led to a 15–95% increase of the activity of eight Calvin cycle enzymes, and increasing the carbon dioxide concentration from 400 to 800 p.p.m. led to a 5–35% decrease of these enzyme activities. The largest changes occurred for aldolase, and for transketolase which also catalyses a reversible reaction and is not subject to ‘fine’ regulation.
A role for glutathione transferases functioning as glutathione peroxidases in resistance to multiple herbicides in black‐grass
Authors: Cummins Ian , Cole David J. , Edwards Robert 
Published: March 2003

SummaryBlack‐grass (Alopecurus myosuroides) is a major weed of wheat in Europe, with several populations having acquired resistance to multiple herbicides of differing modes of action. As compared with herbicide‐susceptible black‐grass, populations showing herbicide cross‐resistance contained greatly elevated levels of a specific type I glutathione transferase (GST), termed AmGST2, but similar levels of a type III GST termed AmGST1. Following cloning and expression of the respective cDNAs, AmGST2 differed from AmGST1 in showing limited activity in detoxifying herbicides but high activities as a glutathione peroxidase (GPOX) capable of reducing organic hydroperoxides. In contrast to AmGST2, other GPOXs were not enhanced in the herbicide‐resistant populations. Treatment with a range of herbicides used to control grass weeds in wheat resulted in increased levels of hydroperoxides in herbicide‐susceptible populations but not in herbicide‐resistant plants, consistent with AmGST2 functioning to prevent oxidative injury caused as a primary or secondary effect of herbicide action. Increased AmGST2 expression in black‐grass was associated with partial tolerance to the peroxidizing herbicide paraquat. The selective enhancement of AmGST2 expression resulted from a constitutively high expression of the respective gene, which was activated in herbicide‐susceptible black‐grass in response to herbicide safeners, dehydration and chemical treatments imposing oxidative stress. Our results provide strong evidence that GSTs can contribute to resistance to multiple herbicides by playing a role in oxidative stress tolerance in addition to detoxifying herbicides by catalysing their conjugation with glutathione.
Translational control in plant stress: the formation of messenger ribonucleoprotein particles (mRNPs) in response to desiccation of Tortula ruralis gametophytes
Authors: Wood Andrew J. , Oliver Melvin J. 
Published: March 2003

SummaryChanges in gene expression observed in vivo in response to desiccation and rehydration of the desiccation‐tolerant bryophyte Tortula ruralis are regulated by alterations in the pattern of selection of messenger RNAs, from a qualitatively constant mRNA pool, by the translational machinery. When drying rates are slow, messenger ribonucleoprotein particles (mRNPs) are formed in the drying gametophytes. A representative rehydrin mRNA, Tr288, was sequestered into these particles which were analysed using sucrose and CsCl gradients. Quantitative RT–PCR analysis of the fractions from a low salt extraction demonstrated that Tr288 mRNA migrated farther in the sucrose gradient, relative to those extractable in high salt, indicating that the transcript is associated with particles that are of higher density. RT–PCR analysis also demonstrated that the majority of Tr288 mRNA, from slowly desiccated gametophytes, is associated with particles that have buoyant densities between 1.44 and 1.64 g cm– 3 which correspond to the buoyant density range reported for mRNP particles. mRNPs that are unique to drying T. ruralis gametophytes form at least four size classes after in vivo UV cross‐linking based upon FPLC analysis. This is the first report of mRNP formation in response to a vegetative water deficit in plants.
Temperature sensing by plants: the primary characteristics of signal perception and calcium response
Authors: Plieth Christoph , Hansen Ulf‐Peter , Knight Heather , Knight Marc R. 
Published: March 2003

Summary Cold elicits an immediate rise in the cytosolic free calcium concentration ([Ca

2+

]

c

) of plant cells. We have studied the concerted action of the three underlying mechanisms, namely sensing, sensitisation and desensitisation, which become important when plants in the field are subjected to changes in temperature. We applied different regimes of temperature changes with well‐defined cooling rates to intact roots of Arabidopsis thaliana expressing the calcium‐indicator, aequorin. Our results indicate that temperature sensing is mainly dependent on the cooling rate, dT/dt, whereas the absolute temperature T is of less importance. Arabidopsis roots were found to be sensitive to cooling rates of less than dT/dt = 0.01°C/s. However, at cooling rates below 0.003°C/s (i.e. cooling 10°C in 1 h) there is no detectable [Ca

2+

]

c

response at all. At low temperature, the sensitivity of the plant cold‐detection system is increased. This in turn produces greater cooling‐induced [Ca

2+

]

c

elevations. Prolonged or repeated cold treatment attenuates the [Ca

2+

]

c

responses to subsequent episodes of cooling.
Leaf C40.4: a carotenoid‐associated protein involved in the modulation of photosynthetic efficiency?
Authors: Monte Elena , Ludevid Dolors , Prat Salomé 
Published: March 2003

SummaryComparative analysis by differential RNA display (DDRT–PCR) of the expression patterns of potato plants induced and non‐induced to tuberize, led to the isolation of a cDNA clone, C40.4, that is strongly upregulated in the leaves of tuberizing plants. Leaf expression of this transcript was shown to be light‐dependent, with increased levels of mRNA and protein being detected during the light hours. Sequence analysis revealed near complete identity to potato CDSP34, a thylakoid protein induced by drought stress, and strong homology to the carotenoid‐associated proteins fibrillin, ChrB and PAP from pepper fruit, and CHRC from cucumber flowers. By using an antibody against pepper fibrillin, we were able to demonstrate a chloroplastic location of the C40.4 protein in association with the thylakoid membranes. Two‐dimensional analysis of thylakoid pigment–protein complexes showed a specific association of the protein with the photosystem II (PSII) multi‐subunit complex. Antisense plants with reduced levels of accumulation of C40.4 showed a stunted growth and decreased tuber yield and exhibited reduced values of non‐photochemical quenching of chlorophyll a fluorescence. Altogether, these results indicate a preferential association of the C40.4 protein with the light harvesting complex of photosystem II (LHCII) antenna pigment complexes, and suggest a functional role of this protein in photosynthesis, by modulating photosynthetic efficiency and dissipation of excess absorbed light energy within the antenna complex.
In vivo analysis of plastid psbA, rbcL and rpl32 UTR elements by chloroplast transformation: tobacco plastid gene expression is controlled by modulation of transcript levels and translation efficiency
Authors: Eibl Christian , Zou Zhurong , Beck Andreas , Kim Minkyun , Mullet John , Koop Hans‐Ulrich 
Published: March 2003

Summary5′ and 3′ untranslated regions (UTRs) of plastid RNAs act as regulatory elements for post‐transcriptional control of gene expression. Polyethylene glycol‐mediated plastid transformation with UTR–GUS reporter gene fusions was used to study the function of the psbA, rbcL and rpl32 UTRs in vivo. All gene fusions were expressed from the same promoter, i.e. the promoter of the 16S‐rRNA gene, such that variations in RNA and protein levels would be due to the involved UTR elements alone. Transgenic tobacco lines containing different combinations of UTRs showed fivefold variation in the uidA–mRNA level (RNA stability) and approximately 100‐fold differences in GUS activity, a measure of translation activity. The rbcL 5′‐UTR conferred greater mRNA stability than the psbA 5′‐UTR on uidA transcripts. In contrast, the psbA 5′‐UTR enhanced translation of GUS to a much greater extent compared to the rbcL 5′‐UTR. The psbA 5′‐UTR also mediated light‐induced activation of translation which was not observed with other constructs. Deletion mutagenesis of an unanalysed terminal sequence element of the psbA 5′‐UTR resulted in a twofold drop in uidA‐mRNA level and a fourfold decrease in translation efficiency. Exchange of 3′‐UTRs results in up to fivefold changes of mRNA levels and does not significantly influence translation efficiency. The mechanical impacts of these results on plastid translation regulation are discussed.
A type 5 acid phosphatase gene from Arabidopsis thaliana is induced by phosphate starvation and by some other types of phosphate mobilising/oxidative stress conditions
Authors: Del Pozo Juan Carlos , Allona Isabel , Rubio Vicente , Leyva Antonio , De La Peña Alicia , Aragoncillo Cipriano , Paz‐Ares Javier 
Published: March 2003

SummaryLow phosphorous availability, a common condition of many soils, is known to stimulate phosphatase activity in plants; however, the molecular details of this response remain mostly unknown. We purified and sequenced the N‐terminal region of a phosphate starvation induced acid phosphatase (AtACP5) from Arabidopsis thaliana, and cloned its cDNA and the corresponding genomic DNA. The nucleotide sequence of the cDNA predicted that AtACP5 is synthesised as a 338 amino acid‐long precursor with a signal peptide. AtACP5 was found to be related to known purple acid phosphatases, especially to mammal type 5 acid phosphatases. Other similarities with purple acid phosphatases, which contain a dinuclear metal centre, include the conservation of all residues involved in metal ligand binding and resistance to tartrate inhibition. In addition, AtACP5, like other type 5 acid phosphatases, displayed peroxidation activity. Northern hybridisation experiments, as well as in situ glucuronidase (GUS) activity assays on transgenic plants harbouring AtACP5:GUS translational fusions, showed that AtACP5 is not only responsive to phosphate starvation but also to ABA and salt stress. It is also expressed in senescent leaves and during oxidative stress induced by H2O2, but not by paraquat or salicylic acid. Given its bifunctionality, as it displays both phosphatase and peroxidation activity, we propose that AtACP5 could be involved in phosphate mobilisation and in the metabolism of reactive oxygen species in stressed or senescent parts of the plant.
Hairpin elements, the first family of foldback transposons (FTs) in Arabidopsis thaliana
Authors: Adé Jules , Belzile François J. 
Published: March 2003

SummaryWe report here on the identification in Arabidopsis thaliana of a new family of transposable elements named Hairpin. These elements are related to foldback transposons (FTs), a large and heterogeneous group of transposable elements first described in Drosophila and recently in Solanaceae. Hairpin elements are the first family of FTs reported in Arabidopsis thaliana and the first family of FTs of type 3 to be described in the plant kingdom. In contrast to previous FTs described, Hairpin appears to be a homogeneous family in size (238 ± 7 bp) as well as in structure. Hairpin elements are dispersed in the Arabidopsis genome and Southern hybridization revealed that they are present in relatively low copy numbers. Finally, we discuss the potential usefulness of these elements in studying the phylogenetic relationship between Arabidopsis ecotypes.
A family of antimicrobial peptides is produced by processing of a 7S globulin protein in Macadamia integrifolia kernels
Authors: Marcus John P. , Green Jodie L. , Goulter Ken C. , Manners John M. 
Published: March 2003

SummaryA new family of antimicrobial peptides has been discovered in Macadamia integrifolia. The first member of this new family to be purified from nut kernels was a peptide of 45 aa residues, termed MiAMP2c. This peptide inhibited various plant pathogenic fungi in vitro. cDNA clones corresponding to MiAMP2c encoded a 666 aa precursor protein homologous to vicilin 7S globulin proteins. The deduced precursor protein sequence contained a putative hydrophobic N‐terminal signal sequence (28 aa), an extremely hydrophilic N‐proximal region (212 aa), and a C‐terminal region of 426 aa which is represented in all vicilins. The hydrophilic portion of the deduced protein contained the sequence for MiAMP2c as well as three additional segments having the same cysteine spacing pattern as MiAMP2c. Each member of the MiAMP2 family (i.e. MiAMP2a, b, c and d) consisted of approximately 50 amino acids and contained a C‐X‐X‐X‐C‐(10–12)X‐C‐X‐X‐X‐C motif. Sub‐ sequent isolations from seed exudates led to the purification of the predicted family members MiAMP2b and 2d, both of which also exhibited antimicrobial activity in vitro. These results suggest that some vicilins play a role in defence during seed germination.
A novel myb oncogene homologue in Arabidopsis thaliana related to hypersensitive cell death
Authors: Daniel Xavier , Lacomme Christophe , Morel Jean‐Benoît , Roby Dominique 
Published: March 2003

SummaryA novel myb oncogene homologue (AtMYB30) has been isolated by differential screening of a cDNA library prepared from Xanthomonas campestris pv. campestris (X. campestris)‐inoculated Arabidopsis thaliana cells cultured in the presence of cycloheximide. AtMYB30 is a single‐copy gene, and the encoded protein contains a MYB domain highly homologous to other plant and animal MYB proteins. Analyses of transcript levels in A. thaliana plants, or in cultured A. thaliana cells infected with either virulent or avirulent strains of the pathogens X. campestris and Pseudomonas syringae pv. tomato, showed that maximal levels of transcription of this gene occurred during the hypersensitive response. Furthermore, in A. thaliana mutants affected in the control of cell death initiation (lsd3, lsd4 and lsd5), constitutive expression or expression in lesion‐positive plants was observed, while in suppressors of the mutations lsd5 and lsd4, AtMYB30 transcripts did not accumulate. However, AtMYB30 expression could not be detected in the lsd1 mutant, which was hyper‐responsive to cell death initiators and unable to limit the extent of cell death, whatever the environmental conditions. The results presented here suggest a strong correlation between AtMYB30 and genetically controlled cell death, with a role in the initiation of cell death rather than in the limitation of its extent. Our results further indicate that the lsd mutants constitute an appropriate genetic model for studying the role of this gene in hypersensitive cell death, and their relation to different steps of the pathway(s) leading to cell death.
A simple, rapid and quantitative method for preparing Arabidopsis protein extracts for immunoblot analysis
Authors: Martínez‐García Jaime F. , Monte Elena , Quail Peter H. 
Published: March 2003

SummaryAlthough Arabidopsis has numerous well documented advantages for genetic and molecular analyses, its small size can be a limitation for biochemical and immunochemical assays requiring protein extraction. We have developed a rapid method to extract total protein from small amounts of Arabidopsis tissue that can be used for quantitative immunoblot analysis. The procedure involves direct extraction of tissue into SDS‐containing buffer under conditions permitting immediate protein quantification in the extract, using commercially available kits without prior fractionation. This approach provides maximal extraction and quantitative recovery of total cellular protein, together with accurate evaluation of target protein levels as a proportion of the total. We have examined the utility and sensitivity of the procedure using monoclonal antibodies to phytochromes A and C (phyA and phyC), which are high‐ and low‐abundance members, respectively, of the phytochrome family in Arabidopsis. Both phytochromes could be rapidly and readily quantified in the tissues examined, with phyC being detectable in extracts representing as few as five dark‐grown seedlings, two light‐grown seedlings, or half a single leaf from 3‐week‐old adult plants. The data indicate that the procedure may have broad utility for the detection and quantitative analysis of many proteins, including those of low abundance, in a variety of applications in Arabidopsis. In one such application, we used transgenic Arabidopsis phyC‐overexpressor seedlings to demonstrate that the procedure can be used to detect transgene‐encoded protein early at the segregating T2 generation, thereby offering the capacity for accelerated screening and selection of lines engineered to overexpress target proteins.