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Search Results: 1 - 10 of 427085 matches for " John M. Manners "
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Hidden weapons of microbial destruction in plant genomes
John M Manners
Genome Biology , 2007, DOI: 10.1186/gb-2007-8-9-225
Abstract: Higher plants are sedentary and lack the adaptive immune system that many animals deploy when challenged by microbial pathogens. Nevertheless, plants are not defenseless, and have developed a variety of mechanisms to protect themselves against microbial attack. These include the production of proteins, secondary metabolites and reactive oxygen species that can inhibit the growth of microbial pathogens, the establishment of structural barriers such as lignin and polysaccharides that prevent penetration and colonization, and hypersensitivity responses that result in programmed cell death and isolate invading pathogens from sources of nutrients.The defensive antimicrobial proteins produced by plants fall into two broad groups based on size. Examples of large antimicrobial proteins (more than 100 amino acid residues) are the chitinases and glucanases that are induced in plant tissues by fungal attack. These digest fungal cell-wall polymers and can inhibit and ultimately lyse fungal cells [1]. Plants also produce a diverse array of smaller proteins (less than 100 amino acid residues), most of which are cysteine-rich peptides (CRPs) that inhibit bacterial and fungal growth in vitro [2]. Many forms of CRPs occur in nature and are believed to comprise an important part of the innate immunity of both plants [3] and animals [4]. In plant tissues, CRPs are produced either constitutively, for example in seeds and reproductive tissues [3], where they can provide a constant defensive role, or can be induced at the site of challenge by a microbial pathogen and subsequently systemically in distal, non-challenged tissues [5]. The best-studied defensive role of CRPs is their ability to inhibit microbial growth in vitro, but many CRPs are inducible by wounding and have defensive roles against chewing insect pests [3,6]. The molecular details of the mode of action of many plant CRPs are unresolved, but one class, the plant defensins, are believed to act through interactions with specif
Early activation of wheat polyamine biosynthesis during Fusarium head blight implicates putrescine as an inducer of trichothecene mycotoxin production
Donald M Gardiner, Kemal Kazan, Sebastien Praud, Francois J Torney, Anca Rusu, John M Manners
BMC Plant Biology , 2010, DOI: 10.1186/1471-2229-10-289
Abstract: Following inoculation of susceptible wheat heads by F. graminearum, DON accumulation was detected at two days after inoculation. The accumulation of putrescine was detected as early as one day following inoculation while arginine and cadaverine were also produced at three and four days post-inoculation. Transcripts of ornithine decarboxylase (ODC) and arginine decarboxylase (ADC), two key biosynthetic enzymes for putrescine biosynthesis, were also strongly induced in heads at two days after inoculation. These results indicated that elicitation of the polyamine biosynthetic pathway is an early response to FHB. Transcripts for genes encoding enzymes acting upstream in the polyamine biosynthetic pathway as well as those of ODC and ADC, and putrescine levels were also induced in the rachis, a flower organ supporting DON production and an important route for pathogen colonisation during FHB. A survey of 24 wheat genotypes with varying responses to FHB showed putrescine induction is a general response to inoculation and no correlation was observed between the accumulation of putrescine and infection or DON accumulation.The activation of the polyamine biosynthetic pathway and putrescine in infected heads prior to detectable DON accumulation is consistent with a model where the pathogen exploits the generic host stress response of polyamine synthesis as a cue for production of trichothecene mycotoxins during FHB disease. However, it is likely that this mechanism is complicated by other factors contributing to resistance and susceptibility in diverse wheat genetic backgrounds.Fusarium head blight (FHB) or scab is one of the most important diseases of wheat and other small grain cereals in many wheat growing regions [1]. FHB is caused mainly by F. graminearum, but also by other related Fusaria. A characteristic of FHB disease is the production of trichothecene mycotoxins such as deoxynivalenol (DON) by the fungus in infected heads. Trichothecenes are phytotoxic [2] and their
A high-throughput method for the detection of homoeologous gene deletions in hexaploid wheat
Timothy L Fitzgerald, Kemal Kazan, Zhongyi Li, Matthew K Morell, John M Manners
BMC Plant Biology , 2010, DOI: 10.1186/1471-2229-10-264
Abstract: To facilitate the screening for specific homoeologous gene deletions in hexaploid wheat, we have developed a TaqMan qPCR-based method that allows high-throughput detection of deletions in homoeologous copies of any gene of interest, provided that sufficient polymorphism (as little as a single nucleotide difference) amongst homoeologues exists for specific probe design. We used this method to identify deletions of individual TaPFT1 homoeologues, a wheat orthologue of the disease susceptibility and flowering regulatory gene PFT1 in Arabidopsis. This method was applied to wheat nullisomic-tetrasomic lines as well as other chromosomal deletion lines to locate the TaPFT1 gene to the long arm of chromosome 5. By screening of individual DNA samples from 4500 M2 mutant wheat lines generated by heavy ion irradiation, we detected multiple mutants with deletions of each TaPFT1 homoeologue, and confirmed these deletions using a CAPS method. We have subsequently designed, optimized, and applied this method for the screening of homoeologous deletions of three additional wheat genes putatively involved in plant disease resistance.We have developed a method for automated, high-throughput screening to identify deletions of individual homoeologues of a wheat gene. This method is also potentially applicable to other polyploidy plants.Identification of plant gene function is important not only to better understand how plants grow and develop, but also for potential exploitation of this information for molecular and/or traditional crop breeding. However, extensive gene duplication and polyploidy events during evolution mean that plants carry multiple copies of the same gene as well as large numbers of closely-related genes [1]. Therefore, for gene function studies, it is important to determine whether different copies of the same or related genes are functionally redundant or whether polymorphisms have been selected through evolution and led to functional specialisation [2,3]. Reverse g
Genomic Analysis of Xanthomonas translucens Pathogenic on Wheat and Barley Reveals Cross-Kingdom Gene Transfer Events and Diverse Protein Delivery Systems
Donald M. Gardiner, Narayana M. Upadhyaya, Jiri Stiller, Jeff G. Ellis, Peter N. Dodds, Kemal Kazan, John M. Manners
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084995
Abstract: In comparison to dicot-infecting bacteria, only limited numbers of genome sequences are available for monocot-infecting and in particular cereal-infecting bacteria. Herein we report the characterisation and genome sequence of Xanthomonas translucens isolate DAR61454 pathogenic on wheat and barley. Based on phylogenetic analysis of the ATP synthase beta subunit (atpD) gene, DAR61454 is most closely related to other X. translucens strains and the sugarcane- and banana- infecting Xanthomonas strains, but shares a type III secretion system (T3SS) with X. translucens pv. graminis and more distantly related xanthomonads. Assays with an adenylate cyclase reporter protein demonstrate that DAR61454's T3SS is functional in delivering proteins to wheat cells. X. translucens DAR61454 also encodes two type VI secretion systems with one most closely related to those found in some strains of the rice infecting strain X. oryzae pv. oryzae but not other xanthomonads. Comparative analysis of 18 different Xanthomonas isolates revealed 84 proteins unique to cereal (i.e. rice) infecting isolates and the wheat/barley infecting DAR61454. Genes encoding 60 of these proteins are found in gene clusters in the X. translucens DAR61454 genome, suggesting cereal-specific pathogenicity islands. However, none of the cereal pathogen specific proteins were homologous to known Xanthomonas spp. effectors. Comparative analysis outside of the bacterial kingdom revealed a nucleoside triphosphate pyrophosphohydrolase encoding gene in DAR61454 also present in other bacteria as well as a number of pathogenic Fusarium species, suggesting that this gene may have been transmitted horizontally from bacteria to the Fusarium lineage of pathogenic fungi. This example further highlights the importance of horizontal gene acquisition from bacteria in the evolution of fungi.
Advances and Challenges in Computational Prediction of Effectors from Plant Pathogenic Fungi
Jana Sperschneider?,Peter N. Dodds?,Donald M. Gardiner?,John M. Manners,Karam B. Singh?,Jennifer M. Taylor
PLOS Pathogens , 2015, DOI: 10.1371/journal.ppat.1004806
Ethylene Response Factor 6 Is a Regulator of Reactive Oxygen Species Signaling in Arabidopsis
Nasser Sewelam, Kemal Kazan, Skye R. Thomas-Hall, Brendan N. Kidd, John M. Manners, Peer M. Schenk
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070289
Abstract: Reactive oxygen species (ROS) are produced in plant cells in response to diverse biotic and abiotic stresses as well as during normal growth and development. Although a large number of transcription factor (TF) genes are up- or down-regulated by ROS, currently very little is known about the functions of these TFs during oxidative stress. In this work, we examined the role of ERF6 (ETHYLENE RESPONSE FACTOR6), an AP2/ERF domain-containing TF, during oxidative stress responses in Arabidopsis. Mutant analyses showed that NADPH oxidase (RbohD) and calcium signaling are required for ROS-responsive expression of ERF6. erf6 insertion mutant plants showed reduced growth and increased H2O2 and anthocyanin levels. Expression analyses of selected ROS-responsive genes during oxidative stress identified several differentially expressed genes in the erf6 mutant. In particular, a number of ROS responsive genes, such as ZAT12, HSFs, WRKYs, MAPKs, RBOHs, DHAR1, APX4, and CAT1 were more strongly induced by H2O2 in erf6 plants than in wild-type. In contrast, MDAR3, CAT3, VTC2 and EX1 showed reduced expression levels in the erf6 mutant. Taken together, our results indicate that ERF6 plays an important role as a positive antioxidant regulator during plant growth and in response to biotic and abiotic stresses.
Comparative Pathogenomics Reveals Horizontally Acquired Novel Virulence Genes in Fungi Infecting Cereal Hosts
Donald M. Gardiner ,Megan C. McDonald,Lorenzo Covarelli,Peter S. Solomon,Anca G. Rusu,Mhairi Marshall,Kemal Kazan,Sukumar Chakraborty,Bruce A. McDonald,John M. Manners
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002952
Abstract: Comparative analyses of pathogen genomes provide new insights into how pathogens have evolved common and divergent virulence strategies to invade related plant species. Fusarium crown and root rots are important diseases of wheat and barley world-wide. In Australia, these diseases are primarily caused by the fungal pathogen Fusarium pseudograminearum. Comparative genomic analyses showed that the F. pseudograminearum genome encodes proteins that are present in other fungal pathogens of cereals but absent in non-cereal pathogens. In some cases, these cereal pathogen specific genes were also found in bacteria associated with plants. Phylogenetic analysis of selected F. pseudograminearum genes supported the hypothesis of horizontal gene transfer into diverse cereal pathogens. Two horizontally acquired genes with no previously known role in fungal pathogenesis were studied functionally via gene knockout methods and shown to significantly affect virulence of F. pseudograminearum on the cereal hosts wheat and barley. Our results indicate using comparative genomics to identify genes specific to pathogens of related hosts reveals novel virulence genes and illustrates the importance of horizontal gene transfer in the evolution of plant infecting fungal pathogens.
Identification of drought-response genes and a study of their expression during sucrose accumulation and water deficit in sugarcane culms
Hayati M Iskandar, Rosanne E Casu, Andrew T Fletcher, Susanne Schmidt, Jingsheng Xu, Donald J Maclean, John M Manners, Graham D Bonnett
BMC Plant Biology , 2011, DOI: 10.1186/1471-2229-11-12
Abstract: A sub-set of stress-related genes that are potentially associated with sucrose accumulation in sugarcane culms was identified through correlation analysis, and these included genes encoding enzymes involved in amino acid metabolism, a sugar transporter and a transcription factor. Subsequent analysis of the expression of these stress-response genes in sugarcane plants that were under water deficit stress revealed a different transcriptional profile to that which correlated with sucrose accumulation. For example, genes with homology to late embryogenesis abundant-related proteins and dehydrin were strongly induced under water deficit but this did not correlate with sucrose content. The expression of genes encoding proline biosynthesis was associated with both sucrose accumulation and water deficit, but amino acid analysis indicated that proline was negatively correlated with sucrose concentration, and whilst total amino acid concentrations increased about seven-fold under water deficit, the relatively low concentration of proline suggested that it had no osmoprotectant role in sugarcane culms.The results show that while there was a change in stress-related gene expression associated with sucrose accumulation, different mechanisms are responding to the stress induced by water deficit, because different genes had altered expression under water deficit.Sugarcane (Saccharum spp.) is a C4 grass with a characteristic ability to accumulate high sucrose concentrations in the culm. Sucrose is synthesized in the leaf mesophyll and transported via the phloem primarily through symplastic transport into storage parenchyma [1]. Accumulation of sucrose in the culm is the net result of sucrose import from the leaf, metabolism within the culm and sucrose export from culm tissue [2]. Sugarcane culm tissues can accumulate sucrose to a concentration of approximately 650 mM in storage parenchyma [3]. It has been suggested that the accumulation of sucrose in the storage parenchyma to such
Poisonous Properties of Larkspur (Delphinium spp.)
Olsen, John D.,Manners, Gary D.,Pelletier, S. W.
Collectanea Botanica , 1990,
Abstract: Some members of the tribe DelphineaeWarming are useful as forage for grazing cattle or as a source of medicaments for man. However, under certain circumstances their consumption results in poisoning, apparently because of norditerpenoid alkaloids. At least 150 diterpenoid alkaloids have been identified in Delphinium. In this report, factors influencing the alkaloid content and the toxicity of the plant are discussed. Relative change in content of eight alkaloids at four stages of growth of Delphinium occidentale (Watson) Watson is reported . The most dominant alkaloids in nine species of Delphinium are listed. Toxicity of eight species was compared al the flower stage of growth using a mouse assay with D. barbeyi; (Huth) Huth being about four times more toxic than D. glaucescens Rydb. or D. geyeri Greene and about ten times more toxic than Consolida CV., D. accidentale, or Aconitum columbianum var. columbianum Nutt. (vegetative stage). Stress by aphid infestation or relatively low water availability had little if any effect on toxicity of D. barbeyi and D. occidentale, respectively. From chemical analysis of D. barbeyi tested previously in cattle. the LD50 for a s ingle intraruminal dose of methyllycaconitine was estimated to be less than 6.3 mg/kg body wt. [ca] Alguns membres de la tribu Delphineae Warming són emprats com a farratge per a bestiar de pastura o com a font de medicaments per a l'home. Tanmateix, sota determinades circumstàncies, el seu consum esdevé intoxicació. aparentment per causa d'alcaloides norditerpènics. Al menys 150 alcaloides diterpènics han estat identificats en Delphinium. En aquest treball es discuteixen els factors que influeixen en el contingut alcalòidic, i, per tant, en la toxicitat de la planla. Es reporten els canvis relatius en el contingut de vuit alcaloides en Quatre estadis de creixement de Delphinium accidentale (Watson) Watson. Els alcaloides dominants en nou espècies de Delphinium es presenten en una llista. La toxicitat de vuit espècies és comparada en estadi de floració, emprant assaigs en rata. D. batbeyi (Huth) Huth és unes Quatre vegades més tòxic Que D. gkmcescens Rydb. o D. geyen Greene, i unes deu vegades més tòxic que un cultivar de Consolida. D. occidentale o Aconitum columbianum var. columbianum Nutt. (en estadi vegetatiu). L'stress causat per infestació d'àfids o per una baixa disponibilitat d'aigua tenen un mínim efecte, sien tenen, sobre la toxicitat de D. barbeyi i D. Occidentale. respectivament. A parti r d'anàlisis quimiques de D. barbeyi prèviament assajades en bestiar. la DL50 per a una única d
Cardiac anaesthesia : current trends and future prospects.
Manners J
Annals of Cardiac Anaesthesia , 2002,
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