bluuebunny/crossref_metadata_2025_split huggingface dataset:
An efficient screen for reproductive pathways using mature seeds of monocots and dicots
Authors: Matzk Fritz , Meister Armin , Schubert Ingo 
Published: March 2003

SummarySeed samples of 32 species (obligate and facultative sexuals and apomicts of monocots and dicots) were investigated by flow cytometry to reveal the pathway of reproduction. Ten different pathways of seed formation could be reconstructed considering whether the female and/or male gametes were reduced or unreduced, the embryos arose via the zygotic or parthenogenetic route and the endosperm via the pseudogamous or autonomous route. The screen is suited to select sporophytic or gametophytic mutants in sexual species, to identify pure sexual or obligate apomictic genotypes from facultative apomictic species, and to analyze the inheritance of the individual reproductive processes. Corresponding unique results are presented for Arabidopsis, Arabis, Hypericum and Poa. The screen of mature seeds by flow cytometry yielded more information about the reproductive behavior of individual plants than any other available test, and is very useful both in basic research and plant breeding.
Movement of plant viruses is delayed in a β‐1,3‐glucanase‐deficient mutant showing a reduced plasmodesmatal size exclusion limit and enhanced callose deposition
Authors: Iglesias Victor Alejandro , Meins Frederick 
Published: March 2003

SummarySusceptibility to virus infection is decreased in a class I β‐1,3‐glucanase (GLU I)‐deficient mutant (TAG4.4) of tobacco generated by antisense transformation. TAG4.4 exhibited delayed intercellular trafficking via plasmodesmata of a tobamovirus (tobacco mosaic virus), of a potexvirus (recombinant potato virus X expressing GFP), and of the movement protein (MP) 3a of a cucumovirus (cucumber mosaic virus). Monitoring the cell‐to‐cell movement of dextrans and peptides by a novel biolistic method revealed that the plasmodesmatal size exclusion limit (SEL) of TAG4.4 was also reduced from 1.0 to 0.85 nm. Therefore, GLU I‐deficiency has a broad effect on plasmodesmatal movement, which is not limited to a particular virus type. Deposition of callose, a substrate for β‐1,3‐glucanases, was increased in TAG4.4 in response to 32°C treatment, treatment with the fungal elicitor xylanase, and wounding, suggesting that GLU I has an important function in regulating callose metabolism. Callose turnover is thought to regulate plasmodesmatal SEL. We propose that GLU I induction in response to infection may help promote MP‐driven virus spread by degrading callose.
Characterization of a nitrate‐permeable channel able to mediate sustained anion efflux in hypocotyl cells from Arabidopsis thaliana
Authors: Frachisse Jean‐Marie , Colcombet Jean , Guern Jean , Barbier‐Brygoo Hélène 
Published: March 2003

SummaryWe have characterized a new anionic current in Arabidopsis hypocotyl cells. This current, activated by membrane depolarization, has slow activation and deactivation kinetics in the 10 sec range. It presents many distinct properties from the rapid‐type anion current already described on the same membrane. The slow‐type channel is highly permeable to nitrate with a PNO3–/PCl– close to 20, but totally impermeable to sulphate. Activation of the channel requires cytosolic ATP and the slow current is partially inhibited by staurosporin, suggesting that channel regulation involves protein phosphorylation. The slow anion channel displays a unique pharmacological profile different from that of the rapid channel: the slow channel is inhibited by DIDS (4,4′‐diisothiocyanatostilbene‐2,2′‐disulfonic acid) with an IC50 of 26 μM. The slow and rapid anion channels are probably dedicated to specific functions: the first is able to mediate sustained anion efflux, while the second is a good candidate to be involved in fast electrical signalling.
Disruption of the Arabidopsis photosystem I gene psaE1 affects photosynthesis and impairs growth
Authors: Varotto Claudio , Pesaresi Paolo , Meurer Jörg , Oelmüller Ralf , Steiner‐Lange Sabine , Salamini Francesco , Leister Dario 
Published: March 2003

SummaryThe psae1‐1 mutant of Arabidopsis was identified on the basis of a decrease in the effective quantum yield of photosystem II, among a collection of plants subjected to transposon tagging with the Enhancer element. The steady‐state redox level and the rate of re‐oxidation of P700 are significantly altered in psae1‐1 mutants. The responsible mutation was localised to psaE1, one of two Arabidopsis genes that encode subunit E of photosystem I. An additional mutant allele, psae1‐2, was identified by reverse genetics. In wild‐type plants, the psaE1 transcript is expressed at a higher level than psaE2 mRNA. In the mutants, however, the E1 transcript was barely detectable, and was expressed only in small groups of wild‐type cells resulting from somatic reversions. As a consequence, the amount of PsaE protein present in the mutant is significantly reduced. Concomitantly, the levels of other stromal photosystem I subunits (PsaC and PsaD) are also affected. Mutant plants showed a marked increase in light sensitivity and photoinhibition. Additional effects of the psae1 mutation include light green pigmentation, an increase in chlorophyll fluorescence and a decrease of approximately 50% in growth rate under greenhouse conditions.
The evolution of C4 plants: acquisition of cis‐regulatory sequences in the promoter of C4‐type pyruvate, orthophosphate dikinase gene
Authors: Nomura Mika , Sentoku Naoki , Nishimura Asuka , Lin Jenq‐Horng , Honda Chikako , Taniguchi Mitutaka , Ishida Yuji , Ohta Shozo , Komari Toshihiko , Miyao‐Tokutomi Mitsue , Kano‐Murakami Yuriko , Tajima Shigeyuki , Ku Maurice S. B. , Matsuoka Makoto 
Published: March 2003

SummaryIn a previous study, we identified the C4‐like pyruvate, orthophosphate dikinase gene (Pdk) in the C3 plant rice, with a similar structure to the C4‐type Pdk in the C4 plant maize. In order to elucidate the differences between C4‐type and C4‐like Pdk genes in C4 and C3 plants, we have produced chimeric constructs with the β‐glucuronidase (GUS) reporter gene under the control of the Pdk promoters. In transgenic rice, both rice and maize promoters directed GUS expression in photosynthetic organs in a light‐dependent manner. However, the maize promoter exhibited a much higher transcriptional activity than the rice promoter did. These results indicate that the rice C4‐like Pdk gene resembles the maize C4‐type Pdk gene in terms of regulation of expression. We also tested the activity of the rice promoter in transgenic maize. GUS activity was seen in both photosynthetic and non‐photosynthetic organs. Thus, the rice promoter does not confer a strict organ‐specific gene expression, as the maize promoter does. Moreover, the rice promoter directed GUS expression not only in mesophyll cells but also in bundle sheath cells, whereas the maize promoter directed expression only in mesophyll cells. Taken together, the results obtained from both transgenic maize and rice demonstrate that the rice and maize promoters differ not only quantitatively, but also qualitatively, in terms of their cell‐ and organ‐specificity. Experiments with swapped promoters using the rice and maize promoters further demonstrated that a limited sequence region from −330 to −76 of the maize promoter confers light‐regulated, high‐level expression to the rice promoter in maize mesophyll protoplasts. We conclude the gain of cis‐acting elements conferring high‐level expression and mesophyll cell specificity was necessary for establishment of a C4‐type Pdk gene during the course of evolution from C3 to C4 plants.
Two bean cell wall proteins more abundant during water deficit are high in proline and interact with a plasma membrane protein
Authors: García‐Gómez Blanca I. , Campos Francisco , Hernández Magdalena , Covarrubias Alejandra A. 
Published: March 2003

SummaryTwo antigenically related glycoproteins, called p33 and p36, accumulate in the soluble fraction of the cell wall in response to water deficit in Phaseolus vulgaris. In this report, we show that p33 and p36 are able to adhere to leaf protoplasts, and that they bind to plasma membrane (PM) vesicles in a divalent cation‐dependent manner. Data from the partial amino acid sequence of the p33 and p36 proteins indicate that they contain repeats of the decapeptide POVYKPOVEK; therefore, they are related to proline‐rich proteins. Binding assays demonstrate that both proteins specifically bind to an 80 kDa PM protein. This binding is competed with a peptide that contains the RGD motif, as well as with fibronectin, which also includes this sequence, suggesting that the 80 kDa PM protein has an integrin‐like function whose natural ligands are p33 and p36. This is the first case where a PM ligand for a higher plant cell wall protein has been identified.
The roles of three functional sulphate transporters involved in uptake and translocation of sulphate in Arabidopsis thaliana
Authors: Takahashi Hideki , Watanabe‐Takahashi Akiko , Smith Frank W. , Blake‐Kalff Mechteld , Hawkesford Malcolm J. , Saito Kazuki 
Published: March 2003

SummaryTo investigate the uptake and long‐distance translocation of sulphate in plants, we have characterized three cell‐type‐specific sulphate transporters, Sultr1;1, Sultr2;1 and Sultr2;2 in Arabidopsis thaliana. Heterologous expression in the yeast sulphate transporter mutant indicated that Sultr1;1 encodes a high‐affinity sulphate transporter (Km for sulphate 3.6 ± 0.6 μm), whereas Sultr2;1 and Sultr2;2 encode low‐affinity sulphate transporters (Km for sulphate 0.41 ± 0.07 m
m and ≥ 1.2 m
m, respectively). In Arabidopsis plants expressing the fusion gene construct of the Sultr1;1 promoter and green fluorescent protein (GFP), GFP was localized in the lateral root cap, root hairs, epidermis and cortex of roots. β‐glucuronidase (GUS) expressed with the Sultr2;1 promoter was specifically accumulated in the xylem parenchyma cells of roots and leaves, and in the root pericycles and leaf phloem. Expression of the Sultr2;2 promoter–GFP fusion gene showed specific localization of GFP in the root phloem and leaf vascular bundle sheath cells. Plants continuously grown with low sulphate concentrations accumulated high levels of Sultr1;1 and Sultr2;1 mRNA in roots and Sultr2;2 mRNA in leaves. The abundance of Sultr1;1 and Sultr2;1 mRNA was increased remarkably in roots by short‐term stress caused by withdrawal of sulphate. Addition of selenate in the sulphate‐sufficient medium increased the sulphate uptake capacity, tissue sulphate content and the abundance of Sultr1;1 and Sultr2;1 mRNA in roots. Concomitant decrease of the tissue thiol content after selenate treatment was consistent with the suggested role of glutathione (GSH) as a repressive effector for the expression of sulphate transporter genes.
Replication of chloroplast, mitochondrial and nuclear DNA during growth of unirradiated and UVB‐irradiated Arabidopsis leaves
Authors: Draper Christopher K. , Hays John B. 
Published: March 2003

SummaryReplication of Arabidopsis nuclear, mitochondrial and chloroplast DNA (ncDNA, mtDNA, cpDNA) was assayed by measuring respective changes in copies per leaf, employing quantitative PCR (QPCR) analysis with genome‐specific primer pairs. All three genomes showed parallel increases during growth of cotyledons and 5th leaves in planta, maintaining approximately 13 mtDNA copies and 280 cpDNA copies per haploid nuclear genome. Detached 5th leaves, which showed good growth and DNA replication on agar plates, were irradiated at (DNA‐effective) UV‐B fluences of 1.3–5.0 kJ m−2 and incubated under blue (photorepair‐active) plus gold light or gold light only. Under blue light, replication of all genomes after all UV fluences was approximately as efficient as replication in unirradiated leaves. UV‐irradiated leaves showed little growth under gold light only; 5 kJ m−2 stopped replication of all three genomes, 2.5 kJ m−2 stopped only cpDNA replication, and 1.3 kJ m−2 only delayed cpDNA replication. Immunoassays showed that 5 kJ m−2 induced about 1.2 cyclobutane pyrimidine dimers and 0.1 [6‐4]photoproducts per kbp of bulk DNA, and that both photoproducts were completely removed during 2–3 days under blue light, suggesting efficient photorepair of at least ncDNA and cpDNA. The evidence for efficient photorepair of organellar DNA contrasts with previous studies of irradiated 5‐day‐old seedlings, and with the apparent absence of Arabidopsis photolyases bearing transit peptides.
Suppression of cell expansion by ectopic expression of the Arabidopsis SUPERMAN gene in transgenic petunia and tobacco
Authors: Kater Martin M. , Franken John , Van Aelst Adriaan , Angenent Gerco C. 
Published: March 2003

SummaryMolecular and genetic analyses have shown that the Arabidopsis thaliana gene SUPERMAN (SUP) has at least two functions in Arabidopsis flower development. SUP is necessary to control the correct distribution of cells with either a stamen or carpel fate, and is essential for proper outgrowth of the ovule outer integument. Both these functions indicate a role for SUP in cell proliferation. To study the function of the Arabidopsis SUP gene in more detail, we over‐expressed the SUP gene in petunia and tobacco in a tissue‐specific manner. The petunia FLORAL BINDING PROTEIN 1 (FBP1) gene promoter was used to restrict the expression of SUP to petals and stamens. The development of petals and stamens was severely affected in both petunia and tobacco plants over‐expressing SUP. Petals remained small and did not unfold, resulting in closed flowers. Stamen filaments were thin and very short. Detailed analysis of these floral organs from the petunia transformants showed that cell expansion was dramatically reduced without affecting cell division. These results reveal a novel activity for SUP as a regulator of cell expansion.
The CYTOKININ‐HYPERSENSITIVE genes of Arabidopsis negatively regulate the cytokinin‐signaling pathway for cell division and chloroplast development
Authors: Kubo Minoru , Kakimoto Tatsuo 
Published: March 2003

SummaryWe isolated Arabidopsis thaliana mutants that respond more sensitively than the wild type to cytokinins. The calli produced from the mutants exhibit typical cytokinin responses, including rapid proliferation and chloroplast development in response to lower levels of cytokinins than in the wild type. The mutations are recessive and belong to two complementation groups designated ckh1 and ckh2 for cytokinin‐hypersensitive. CKH1 and CKH2 were mapped to the top of chromosome I and the middle of chromosome II, respectively. The cytokinin levels in these mutants were not increased. We speculate that the CKH1 and CKH2 gene products negatively regulate the signaling pathway leading from cytokinin perception to cell proliferation and chloroplast development.
The role of inorganic phosphate in the development of freezing tolerance and the acclimatization of photosynthesis to low temperature is revealed by the pho mutants of Arabidopsis thaliana
Authors: Hurry Vaughan , Strand Åsa , Furbank Robert , Stitt Mark 
Published: March 2003

SummaryLow temperature inhibits sucrose synthesis, leading to a phosphate‐limitation of photosynthesis. We have used the Arabidopsis pho1‐2 and pho2‐1 mutants with decreased and increased shoot phosphate, respectively, to investigate whether low phosphate triggers cold acclimatization of photosynthetic carbon metabolism. Wild‐type Arabidopsis, pho1‐2 and pho2‐1 were grown at 23°C and transferred to 5°C to investigate acclimatization in pre‐existing leaves and in new leaves developing at 5°C. The development of frost tolerance and the accumulation of proline and sugars was unaltered or improved in pho1‐2, and impaired in pho2‐1. Sucrose phosphate synthase and cytoplasmic fructose‐1,6‐bisphosphatase activity and protein increase after transfer to 5°C. This increase was accentuated in pho1‐2 and attenuated in pho2‐1. RBCS and LHCB2 transcript levels decrease in pre‐formed wild‐type leaves after transfer to 5°C and recover in new leaves that develop at 5°C. The initial decrease was attenuated in pho1‐2, and accentuated in pho2‐1, where the recovery in new leaves was also suppressed. Rubisco activity increased in wild‐type leaves that developed at 5°C. This increase was accentuated in pho1‐2 and absent in pho2‐1. NADP‐glyceraldehyde‐3‐phosphate dehydrogenase, plastidic fructose‐1,6‐bisphosphatase and aldolase activity increase relative to phosphoglycerate kinase, transketolase and phosphoribulokinase in wild‐type leaves at 5°C. This shift was accentuated in pho1‐2 and reversed in pho2‐1. Transcript levels for COR genes increase transiently 1 day after transfer to 5°C but were very low in leaves that developed at 5°C in wild‐type Arabidopsis, pho1‐2 and pho2‐1. We conclude that low phosphate plays an important role in triggering cold acclimatization of leaves, leading in particular to an increase of Rubisco expression, changes in other Calvin cycle enzymes to minimize sequestration of phosphate in metabolites, and increased expression of sucrose biosynthesis enzymes.
Influence of cytokinins on the expression of phosphate starvation responsive genes in Arabidopsis
Authors: Martín Ana C. , Del Pozo Juan Carlos , Iglesias Joaquín , Rubio Vicente , Solano Roberto , De La Peña Alicia , Leyva Antonio , Paz‐Ares Javier 
Published: March 2003

SummaryThe increase in the ratio of root growth to shoot growth that occurs in response to phosphate (Pi) deprivation is paralleled by a decrease in cytokinin levels under the same conditions. However, the role of cytokinin in the rescue system for Pi starvation remains largely unknown. We have isolated a gene from Arabidopsis thaliana (AtIPS1) that is induced by Pi starvation, and studied the effect of cytokinin on its expression in response to Pi deprivation. AtIPS1 belongs to the TPSI1/Mt4 family, the members of which are specifically induced by Pi starvation, and the RNAs of which contain only short, non‐conserved open reading frames. Pi deprivation induces AtIPS1 expression in all cells of wild‐type plants, whereas in the pho1 mutant grown on Pi‐rich soils, AtIPS1 expression in the root was delimited by the endodermis. This supports the view that pho1 is impaired in xylem loading of Pi, and that long‐distance signals controlling the Pi starvation responses act via negative control. Exogenous cytokinins repress the expression of AtIPS1 and other Pi starvation‐responsive genes in response to Pi deprivation. However, cytokinins did not repress the increase in root‐hair number and length induced by Pi starvation, a response dependent on local Pi concentration rather than on whole‐plant Pi status. Our results raise the possibility that cytokinins may be involved in the negative modulation of long‐distance, systemically controlled Pi starvation responses, which are dependent on whole‐plant Pi status.
Expression of the plant cyclin‐dependent kinase inhibitor ICK1 affects cell division, plant growth and morphology
Authors: Wang Hong , Zhou Yongming , Gilmer Susan , Whitwill Steve , Fowke Larry C. 
Published: March 2003

SummaryThe plant CDK inhibitor ICK1 was identified previously from Arabidopis thaliana with its inhibitory activity characterized in vitro. ICK1 displayed several structural and functional features that are distinct from known animal CDK inhibitors. Despite the initial characterization, there is no information on the functions of any plant CDK inhibitor in plants. To gain insight into ICK1 functions in vivo and the role of cell division during plant growth and development, transgenic plants were generated expressing ICK1 driven by the cauliflower mosaic virus 35S promoter. In comparison to control plants, growth was significantly inhibited in transgenic 35S‐ICK1 plants, with some plants weighing <10% of wild‐type plants at the 3 week stage. Most organs of 35S‐ICK1 plants were smaller. There were also modifications in plant morphology such as shape and serration of leaves and petals. The changes were so drastic that 35S‐ICK1 plants with strong phenotype no longer resembled wild‐type plants morphologically. Analyses showed that increased ICK1 expression resulted in reduced CDK activity and reduced the number of cells in these plants. Cells in 35S‐ICK1 plants were larger than corresponding cells in control plants. These results demonstrate that ICK1 acts as a CDK inhibitor in the plant, and the inhibition of cell division by ICK1 expression has profound effects on plant growth and development. They also suggest that alterations of plant organ shape can be achieved by restriction of cell division.
A MADS domain gene involved in the transition to flowering in Arabidopsis
Authors: Borner Rony , Kampmann Grit , Chandler John , Gleißner Roland , Wisman Ellen , Apel Klaus , Melzer Siegbert 
Published: March 2003

SummaryFlowering time in many plants is triggered by environmental factors that lead to uniform flowering in plant populations, ensuring higher reproductive success. So far, several genes have been identified that are involved in flowering time control. AGL20 (AGAMOUSLIKE20) is a MADS domain gene from Arabidopsis that is activated in shoot apical meristems during the transition to flowering. By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control. In previously described late flowering mutants of the long‐day and constitutive pathways of floral induction the expression of AGL20 is down‐regulated, demonstrating that AGL20 acts downstream to the mutated genes. Moreover, we can show that AGL20 is also regulated by the gibberellin (GA) pathway, indicating that AGL20 integrates signals of different pathways of floral induction and might be a central component for the induction of flowering. In addition, the constitutive expression of AGL20 in Arabidopsis is sufficient for photoperiod independent flowering and the over‐expression of the orthologous gene from mustard, MADSA, in the classical short‐day tobacco Maryland Mammoth bypasses the strict photoperiodic control of flowering.
A novel cold‐inducible zinc finger protein from soybean, SCOF‐1, enhances cold tolerance in transgenic plants
Authors: Kim Jong Cheol , Lee Sang Hyoung , Cheong Yong Hwa , Yoo Cheol‐Min , Lee Soo In , Chun Hyun Jin , Yun Dae‐Jin , Hong Jong Chan , Lee Sang Yeol , Lim Chae Oh , Cho Moo Je 
Published: March 2003

SummaryCold stress on plants induces changes in the transcription of cold response genes. A cDNA clone encoding C2H2‐type zinc finger protein,SCOF‐1, was isolated from soybean. The transcription ofSCOF‐1is specifically induced by low temperature and abscisic acid (ABA) but not by dehydration or high salinity. Constitutive overexpression ofSCOF‐1induced cold‐regulated (COR) gene expression and enhanced cold tolerance of non‐acclimated transgenicArabidopsisand tobacco plants. SCOF‐1 localized to the nucleus but did not bind directly to either C‐repeat/dehydration (CRT/DRE) or ABA responsive element (ABRE),cis‐acting DNA regulatory elements present inCORgene promoters. However, SCOF‐1 greatly enhanced the DNA binding activity of SGBF‐1, a soybean G‐box binding bZIP transcription factor, to ABREin vitro. SCOF‐1 also interacted with SGBF‐1 in a yeast two‐hybrid system. The SGBF‐1 transactivated theβ‐glucuronidasereporter gene driven by the ABRE element inArabidopsisleaf protoplasts. Furthermore, the SCOF‐1 enhanced ABRE‐dependent gene expression mediated by SGBF‐1. These results suggest that SCOF‐1 may function as a positive regulator ofCORgene expression mediated by ABRE via protein–protein interaction, which in turn enhances cold tolerance of plants.