bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationships between temperature and latent periods of rust and leaf‐spot diseases of groundnut
Authors: WADIA K. D. R. , BUTLER D. R. 
Published: April 2007

The effect of temperature on the latent periods of rust, late leaf spot and early leaf spot diseases of groundnut caused by Puccinia arachidis, Phaeoisariopsis personata and Cercospora arachidicola, respectively, was studied. The latent periods (LP) of rust, late leaf spot and early leaf spot ranged from 12–49 days, 13–38 days and 13–39 days, respectively, between 12°C and 33°C An equation relating the rate of pathogen development (1/LP) to temperature was fitted using daily mean temperatures to provide three cardinal temperatures: the minimum (Tmln), optimum (Topl), and maximum (Tmax), Tmln was about 12°C for rust and about 10°C for the two leaf‐spot diseases. Topt, for all three diseases was close to 25°C. Tmax was 31°C for early leaf spot, and extrapolated values for late leaf spot and rust were about 35 and 40°C, respectively.For P. personata, a temperature response curve was fitted using data only from controlled environment experiments. This curve was used to simulate latent periods from both mean daily and mean hourly temperatures in the field. There was substantially better agreement between observed and simulated latent period with hourly temperatures, provided the developmental rate of the pathogen was determined at a constant temperature.
Variations in isolates of Mycogone perniciosa and in disease symptoms in Agaricus bisporus
Authors: FLETCHER J. T. , JAFFE B. , MUTHUMEENAKSHI S. , BROWN A. E. , WRIGHT D. M. 
Published: April 2007

Eight isolates of Mycogone perniciosa, five from Agaricus bisporus and three from Agaricus arvensis, were studied. One isolate of Mycogone rosae was also included. Aleuriospore and phialospore morphology varied among the isolates as did other characteristics, but M. rosae was the only isolate to produce a red colouration of the medium. Growth was also variable, with three isolates of M. pemiciosa growing at about half the rate of the fastest. The slow‐growing isolates contained virus‐like particles, 36 nm diameter, and produced sclerodermoid mushrooms. The fast‐growing isolates did not contain virus‐like particles and caused cap spotting, a symptom not previously described for M. perniciosa. M. rosae produced characteristic cap spots and no scierodermoid mushrooms. A comparison of two isolates of St. perniciosa. one from A. bisporus and one from A arvensis, showed a much greater yield reduction as a result of symptoms caused by the isolate from A. bisporus. The isolate of M. rosae had no significant effect on yield.Restriction fragment banding patterns of ribosomal DNA showed no differences among the seven isolates of M. perniciosa from England, but the isolate from China was slightly different. The single isolate of M. rosae was distinct from M. perniciosa.
Population diversity of Pseudomonas syringae subsp. savastanoi on olive and oleander
Authors: CAPONERO A. , CONTESINI A. M. , IACOBELLIS N. S. 
Published: April 2007

Twenty‐one strains of Pseudomonas syringae subsp. savastanoi, isolated from knots on olive and oleander trees growing in close proximity to or in physical contact with one another, were evaluated for knot induction and for bacteriocin production. In addition, DNA preparations from the bacterial strains were tested for hybridization to probes containing the tryptophan monooxygenase (iaaM) and isopentenyl transferase (ipt) genes, which are involved in indole‐3‐acetic acid and cytokinin biosynthesis, respectively, in P.s. subsp. savastanoi.The strains showed features characteristic of strains usually isolated from their respective host plants. For example, all 10 oleander strains were virulent both to oleander and olive, did not produce bacteriocins and harboured the iaaM gene on plasmids. In contrast, all 11 olive strains were virulent only to olive, 10 strains produced bacteriocins, and nine strains carried the iaaM gene on the chromosome. Two olive strains (OAll, OD21) harboured the gene coding for iaaM on plasmids. Furthermore, strain OD21 carried the iaaM gene on the same plasmid as the ipt gene. This is the first report both of a plasmid‐borne iaaM in typical olive strains (virulent only to olive and bacteriocin producers), and of the presence of the ipt gene on the same plasmid. In olive and oleander strains the ipt gene was located either on plasmids or on the chromosome. These results suggest that under natural conditions the pathogen does not appear to spread from oleander to olive even when trees are growing in close proximity or in physical contact.The location of the phytohormone genes on plasmids or on the chromosome is discussed in relationship to bacteriocin‐production and knot‐induction on the host species.
AAP1 transports uncharged amino acids into roots of Arabidopsis
Authors: Lee Yong‐Hwa , Foster Justin , Chen Janet , Voll Lars M. , Weber Andreas P.M. , Tegeder Mechthild 
Published: April 2007

SummaryAmino acids are available to plants in some soils in significant amounts, and plants frequently make use of these nitrogen sources. The goal of this study was to identify transporters involved in the uptake of amino acids into root cells. Based on the fact that high concentrations of amino acids inhibit plant growth, we hypothesized that mutants tolerating toxic levels of amino acids might be deficient in the uptake of amino acids from the environment. To test this hypothesis, we employed a forward genetic screen for Arabidopsis thaliana mutants tolerating toxic concentrations of amino acids in the media. We identified an Arabidopsis mutant that is deficient in the amino acid permease 1 (AAP1, At1g58360) and resistant to 10 mm phenylalanine and a range of other amino acids. The transporter was localized to the plasma membrane of root epidermal cells, root hairs, and throughout the root tip of Arabidopsis. Feeding experiments with [14C]‐labeled neutral, acidic and basic amino acids showed significantly reduced uptake of amino acids in the mutant, underscoring that increased tolerance of aap1 to high levels of amino acids is coupled with reduced uptake by the root. The growth and uptake studies identified glutamate, histidine and neutral amino acids, including phenylalanine, as physiological substrates for AAP1, whereas aspartate, lysine and arginine are not. We also demonstrate that AAP1 imports amino acids into root cells when these are supplied at ecologically relevant concentrations. Together, our data indicate an important role of AAP1 for efficient use of nitrogen sources present in the rhizosphere.
Phytochrome coordinates Arabidopsis shoot and root development
Authors: Salisbury Frances J. , Hall Anthony , Grierson Claire S. , Halliday Karen J. 
Published: April 2007

SummaryThe phytochrome family of photoreceptors are potent regulators of plant development, affecting a broad range of responses throughout the plant life cycle, including hypocotyl elongation, leaf expansion and apical dominance. The plant hormone auxin has previously been linked to these phytochrome‐mediated responses; however, these studies have not identified the molecular mechanisms that underpin such extensive phytochrome and auxin cross‐talk. In this paper, we show that phytochrome regulates the emergence of lateral roots, at least partly by manipulating auxin distribution within the seedling. Thus, shoot‐localized phytochrome is able to act over long distances, through manipulation of auxin, to regulate root development. This work reveals an important role for phytochrome as a coordinator of shoot and root development, and provides insights into how phytochrome is able to exert such a powerful effect on growth and development. This new link between phytochrome and auxin may go some way to explain the extensive overlap in responses mediated by these two developmental regulators.
Overexpression of CRK13, an Arabidopsis cysteine‐rich receptor‐like kinase, results in enhanced resistance to Pseudomonas syringae
Authors: Acharya Biswa R. , Raina Surabhi , Maqbool Shahina B. , Jagadeeswaran Guru , Mosher Stephen L , Appel Heidi M. , Schultz Jack C. , Klessig Daniel F. , Raina Ramesh 
Published: April 2007

SummaryProtein kinases play important roles in relaying information from perception of a signal to the effector genes in all organisms. Cysteine‐rich receptor‐like kinases (CRKs) constitute a sub‐family of plant receptor‐like kinases (RLKs) with more than 40 members that contain the novel C‐X8‐C‐X2‐C motif (DUF26) in the extracellular domains. Here we report molecular characterization of one member of this gene family, CRK13. Expression of this gene is induced more quickly and strongly in response to the avirulent compared with the virulent strains of Pseudomonas syringae, and peaks within 4 h after pathogen infection. In response to dexamethasone (DEX) treatment, plants expressing the CRK13 gene from a DEX‐inducible promoter exhibited all tested features of pathogen defense activation, including rapid tissue collapse, accumulation of high levels of several defense‐related gene transcripts including PR1, PR5 and ICS1, and accumulation of salicylic acid (SA). In addition, these plants suppressed growth of virulent pathogens by about 20‐fold compared with the wild‐type Col‐0. CRK13‐conferred pathogen resistance is salicylic acid‐dependent. Gene expression analysis using custom cDNA microarrays revealed a remarkable overlap between the expression profiles of the plants overexpressing CRK13 and the plants treated with Pst DC3000 (avrRpm1). Our studies suggest that upregulation of CRK13 leads to hypersensitive response‐associated cell death, and induces defense against pathogens by causing increased accumulation of salicylic acid.
Arbuscular mycorrhizal symbiosis is accompanied by local and systemic alterations in gene expression and an increase in disease resistance in the shoots
Authors: Liu Jinyuan , Maldonado‐Mendoza Ignacio , Lopez‐Meyer Melina , Cheung Foo , Town Christopher D. , Harrison Maria J. 
Published: April 2007

SummaryIn natural ecosystems, the roots of many plants exist in association with arbuscular mycorrhizal (AM) fungi, and the resulting symbiosis has profound effects on the plant. The most frequently documented response is an increase in phosphorus nutrition; however, other effects have been noted, including increased resistance to abiotic and biotic stresses. Here we used a 16 000‐feature oligonucleotide array and real‐time quantitative RT‐PCR to explore transcriptional changes triggered in Medicago truncatula roots and shoots as a result of AM symbiosis. By controlling the experimental conditions, phosphorus‐related effects were minimized, and both local and systemic transcriptional responses to the AM fungus were revealed. The transcriptional response of the roots and shoots differed in both the magnitude of gene induction and the predicted functional categories of the mycorrhiza‐regulated genes. In the roots, genes regulated in response to three different AM fungi were identified, and, through split‐root experiments, an additional layer of regulation, in the colonized or non‐colonized sections of the mycorrhizal root system, was uncovered. Transcript profiles of the shoots of mycorrhizal plants indicated the systemic induction of many genes predicted to be involved in stress or defense responses, and suggested that mycorrhizal plants might display enhanced disease resistance. Experimental evidence supports this prediction, and mycorrhizal M. truncatula plants showed increased resistance to a virulent bacterial pathogen, Xanthomonas campestris. Thus, the symbiosis is accompanied by a complex pattern of local and systemic changes in gene expression, including the induction of a functional defense response.
QQT proteins colocalize with microtubules and are essential for early embryo development in Arabidopsis
Authors: Lahmy Sylvie , Guilleminot Jocelyne , Schmit Anne‐Catherine , Pelletier Georges , Chaboute Marie‐Edith , Devic Martine 
Published: April 2007

SummaryDuring Arabidopsis embryogenesis, the control of division between daughter cells is critical for pattern formation. Two embryo‐defective (emb) mutant lines named quatre‐quart (qqt) were characterized by forward and reverse genetics. The terminal arrest of qqt1 and qqt2 embryos was at the octant stage, just prior to the round of periclinal divisions that establishes the dermatogen stage . Homozygous embryos of a weaker allele of qqt1 were able to divide further, resulting in aberrant periclinal divisions. These phenotypic analyses support an essential role of the QQT proteins in the correct formation of the tangential divisions. That an important proportion of qqt1 embryos were arrested prior to the octant stage indicated a more general role in cell division. The analysis of QQT1 and QQT2 genes revealed that they belong to a small subgroup of the large family encoding ATP/GTP binding proteins, and are widely conserved among plants, vertebrates and Archaea. We showed that QQT1 and QQT2 proteins interact with each other in a yeast two‐hybrid system, and that QQT1 and QQT2 tagged by distinct fluorescent probes colocalize with microtubules during mitosis, in agreement with their potential role in cell division and their mutant phenotype. We propose that QQT1 and QQT2 proteins participate in the organization of microtubules during cell division, and that this function is essential for the correct development of the early embryo.
RNA silencing and its cell‐to‐cell spread during Arabidopsis embryogenesis
Authors: Kobayashi Ken , Zambryski Patricia 
Published: April 2007

SummaryIn plants, post‐transcriptional RNA silencing (PTGS) signals move beyond their sites of synthesis using channels called plasmodesmata (PD). However, a potential influence of PD permeability in silencing signal movement has not been addressed previously. PD connectivity and aperture are routinely determined by monitoring the cell‐to‐cell movement of protein tracers of different sizes. Here we compare protein and RNA silencing signal movement during Arabidopsis embryogenesis. The data suggest that the degree of PTGS signal movement correlates with the degree of PD aperture previously determined in distinct subregions of the developing Arabidopsis embryo. Silencing signals move more extensively in the hypocotyl and root compared with the area around the tips of the cotyledons, suggesting that the site of silencing signal initiation influences the extent of signal movement. In addition, we found a putative boundary for silencing spread just below the shoot apical meristem that blocks movement upward from the root and hypocotyl. Finally, as PD aperture affects protein movement in embryos, we compared the movement patterns of protein tracers versus the movement patterns of RNA silencing signals. The data reveal that silencing signal complexes move to a similar extent as soluble proteins between 27–54 kDa.
Transcriptome profiling of maize anthers using genetic ablation to analyze pre‐meiotic and tapetal cell types
Authors: Ma Jiong , Duncan David , Morrow Darren J. , Fernandes John , Walbot Virginia 
Published: April 2007

SummaryOligonucleotide arrays were used to profile gene expression in dissected maize anthers at four stages: after‐anther initiation, at the rapid mitotic proliferation stage, pre‐meiosis, and meiotic prophase I. Nearly 9200 sense and antisense transcripts were detected, with the most diverse transcriptome present at the pre‐meiotic stage. Three male‐sterile mutants lacking a range of normal cell types resulting from a temporal progression of anther failure were compared with fertile siblings at equivalent stages by transcription profiles. The msca1 mutant has the earliest visible phenotype, develops none of the normal anther cell types and exhibits the largest deviation from fertile siblings. The mac1 mutant has an excess of archesporial derivative cells and lacks a tapetum and middle layer, resulting in moderate transcriptional deviations. The ms23 mutant lacks a differentiated tapetum and shows the fewest differences from fertile anthers. By combining the data sets from the comparisons between individual sterile and fertile anthers, candidate genes predicted to play important roles during maize anther development were assigned to stages and to likely cell types. Comparative analyses with a data set of anther‐specific genes from rice highlight remarkable quantitative similarities in gene expression between these two grasses.
Environmental and hormonal regulation of the activity–dormancy cycle in the cambial meristem involves stage‐specific modulation of transcriptional and metabolic networks
Authors: Druart Nathalie , Johansson Annika , Baba Kyoko , Schrader Jarmo , Sjödin Andreas , Bhalerao Rupali R. , Resman Lars , Trygg Johan , Moritz Thomas , Bhalerao Rishikesh P. 
Published: April 2007

SummaryWe have performed transcript and metabolite profiling of isolated cambial meristem cells of the model tree aspen during the course of their activity–dormancy cycle to better understand the environmental and hormonal regulation of this process in perennial plants. Considerable modulation of cambial transcriptome and metabolome occurs throughout the activity–dormancy cycle. However, in addition to transcription, post‐transcriptional control is also an important regulatory mechanism as exemplified by the regulation of cell‐cycle genes during the reactivation of cambial cell division in the spring. Genes related to cold hardiness display temporally distinct induction patterns in the autumn which could explain the step‐wise development of cold hardiness. Factors other than low temperature regulate the induction of early cold hardiness‐related genes whereas abscisic acid (ABA) could potentially regulate the induction of late cold hardiness‐related genes in the autumn. Starch breakdown in the autumn appears to be regulated by the ‘short day’ signal and plays a key role in providing substrates for the production of energy, fatty acids and cryoprotectants. Catabolism of sucrose and fats provides energy during the early stages of reactivation in the spring, whereas the reducing equivalents are generated through activation of the pentose phosphate shunt. Modulation of gibberellin (GA) signaling and biosynthesis could play a key role in the regulation of cambial activity during the activity–dormancy cycle as suggested by the induction of PttRGA which encodes a negative regulator of growth in the autumn and that of a GA‐20 oxidase, a key gibberellin biosynthesis gene during reactivation in spring. In summary, our data reveal the dynamics of transcriptional and metabolic networks and identify potential targets of environmental and hormonal signals in the regulation of the activity–dormancy cycle in cambial meristem.
Receptor‐like protein kinase 2 (RPK 2) is a novel factor controlling anther development in Arabidopsis thaliana
Authors: Mizuno Shinji , Osakabe Yuriko , Maruyama Kyonoshin , Ito Takuya , Osakabe Keishi , Sato Takahide , Shinozaki Kazuo , Yamaguchi‐Shinozaki Kazuko 
Published: April 2007

SummaryReceptor‐like kinases (RLK) comprise a large gene family within the Arabidopsis genome and play important roles in plant growth and development as well as in hormone and stress responses. Here we report that a leucine‐rich repeat receptor‐like kinase (LRR‐RLK), RECEPTOR‐LIKE PROTEIN KINASE2 (RPK2), is a key regulator of anther development in Arabidopsis. Two RPK2 T‐DNA insertional mutants (rpk2‐1 and rpk2‐2) displayed enhanced shoot growth and male sterility due to defects in anther dehiscence and pollen maturation. The rpk2 anthers only developed three cell layers surrounding the male gametophyte: the middle layer was not differentiated from inner secondary parietal cells. Pollen mother cells in rpk2 anthers could undergo meiosis, but subsequent differentiation of microspores was inhibited by tapetum hypertrophy, with most resulting pollen grains exhibiting highly aggregated morphologies. The presence of tetrads and microspores in individual anthers was observed during microspore formation, indicating that the developmental homeostasis of rpk2 anther locules was disrupted. Anther locules were finally crushed without stomium breakage, a phenomenon that was possibly caused by inadequate thickening and lignification of the endothecium. Microarray analyses revealed that many genes encoding metabolic enzymes, including those involved in cell wall metabolism and lignin biosynthesis, were downregulated throughout anther development in rpk2 mutants. RPK2 mRNA was abundant in the tapetum of wild‐type anthers during microspore maturation. These results suggest that RPK2 controls tapetal cell fate by triggering subsequent tapetum degradation, and that mutating RPK2 impairs normal pollen maturation and anther dehiscence due to disruption of key metabolic pathways.
Differentiating bipolar disorder in Turkish prepubertal children with attention‐deficit hyperactivity disorder
Authors: Diler Rasim Somer , Uguz Sukru , Seydaoglu Gulsah , Erol Nese , Avci Ayse 
Published: April 2007

Background:  Attention‐deficit hyperactivity disorder (ADHD) and bipolar disorder (BPD) in children are frequently comorbid conditions. Because the coexistence of ADHD and mania seriously complicates the course of the condition and the treatment of children, diagnosing or missing this comorbidity has important clinical implications. There are very few systematic studies on the subject in the literature and BPD in children is not recognized or studied in most countries other than the USA. We aimed to differentiate Turkish prepubertal children with ADHD from those with comorbid ADHD and BPD and compare their clinical characteristics.Methods:  A total of 147 treatment‐ and drug‐naïve children, aged 7 to 13 years, who had been consecutively referred to the ADHD clinic, were evaluated using the Schedule for Affective Disorders and Schizophrenia for School‐age Children–Present and Lifetime version (K–SADS–PL). Parents completed the Child Behavior Checklist (CBCL) 4–18 and the Parent–Young Mania Rating Scale (P–YMRS) prior to the clinical interview.Results:  Twelve children (8.2%) had comorbid bipolar disorder (ADHD + BPD). The ADHD + BPD group had significantly higher rates of depressive disorders, oppositional defiant disorder, panic disorder and a family history of bipolar disorder compared with the ADHD group. The ADHD + BPD group had significantly more problems on the CBCL scale (anxiety/depression, social problems, thought problems, aggression, externalization, and total score) and on the P–YMRS (all items except for insight) compared with the ADHD group.Conclusions:  We conclude that ADHD + BPD in Turkish children represents a clinical picture different to that of ADHD alone, in which the clinical characteristics resemble those of children reported in the literature. Further long‐term follow‐up studies are needed in larger clinical and community samples.
Anticonvulsant efficacy of valproate‐like carboxylic acids: a potential target for anti‐bipolar therapy
Authors: Azab Abed N , Greenberg Miriam L 
Published: April 2007

Background:  Bipolar disorder (BPD) is a severe and chronic illness, with a lifetime prevalence of approximately 1.5%. Despite the availability of some mood stabilizing drugs including lithium, valproate (valproic acid), lamotrigine and carbamazepine, BPD is characterized by high rates of recurrence, as treatment with these and other drugs is ineffective for and not well‐tolerated by a significant percentage of patients. Most drugs currently used for the maintenance treatment of BPD are anticonvulsants (e.g., valproate, carbamazepine and lamotrigine).Objectives:  The aim of this paper is to review the studies characterizing the anticonvulsant efficacy of valproate‐like carboxylic acids and related compounds, some of which may have potential for the treatment of manic‐depressive illness.Results:  The data reviewed herein demonstrate clearly that some dietary fatty acids and other valproate‐like carboxylic acids exhibit potent anticonvulsant activity, and may thus be candidates for mood stabilizing treatment options for BPD.