| molecular differentiation and diversity among the california red oaks (fagaceae; quercus section lobatae). | a recent epidemic of phytopthora (sudden oak death) in coastal woodlands of california is causing severe mortality in some oak species belonging to the red oak (lobatae) group. to predict the risks of spread of this disease, an understanding of the relationships among california's red oak species and of their population genetic structure is needed. we focus here on relationships among the four species of red oak. whereas morphological distinction of quercus wislizeni and quercus parvula can pose ... | 2003 | 12761621 |
| sudden oak death: phytophthora ramorum exhibits transatlantic differences. | | 2003 | 12825493 |
| phylogenetic relationships of phytophthora ramorum, p. nemorosa, and p. pseudosyringae, three species recovered from areas in california with sudden oak death. | sudden oak death has been an emerging disease problem in coastal california and has caused significant losses in forest ecosystems in some regions of the state. the causal agent of this disease has been described as phytophthora ramorum with two other less aggressive species, p. nemorosa and p. pseudosyringae, recovered from some symptomatic plants. the phylogenetic relationship of these species with other members of the genus was examined by sequence alignment of 667 bp of the mitochondrially-e ... | 2003 | 15000239 |
| plant pathology. nurseries may have shipped sudden oak death pathogen nationwide. | | 2004 | 15044777 |
| rapid identification of phytophthora ramorum using pcr-sscp analysis of ribosomal dna its-1. | the primary objectives of this study were to determine if a single-strand conformation polymorphism (sscp) analysis can be used for rapid identification of phytophthora ramorum, an important quarantine plant pathogen worldwide, and to further assess the potential of the sscp technique as a taxonomic tool for the genus phytophthora. | 2004 | 15059217 |
| phytopthora ramorum in belgium: 2002 survey results and research efforts. | phytophthora ramorum is a new and aggressive phytophthora species that causes leaf blight and dieback symptoms on viburnum and rhododendron plants in europe. a variant of this fungus is responsible for sudden oak death (sod) in california and oregon. in europe, problems so far are mostly restricted to nursery plants of rhododendron and viburnum while in the us, the fungus has been isolated from over 20 host species and is responsible for massive killing of oak trees (mostly quercus agrifolia and ... | 2003 | 15151294 |
| aflp and phylogenetic analyses of north american and european populations of phytophthora ramorum. | the genetic structure within and between usa and european populations of the emerging phytopathogen phytophthora ramorum was examined. four primer combinations were used for amplified fragment length polymorphism (aflp) fingerprinting of 67 usa isolates from california and oregon, and 18 european isolates from belgium, germany, the netherlands, spain and the uk. in addition, three dna regions (its, cox ii, and nad 5) of additional phytophthora species were amplified by polymerase chain reaction, ... | 2004 | 15209278 |
| ecological society of america meeting. fighting sudden oak death with fire? | | 2004 | 15326331 |
| production of gametangia by phytophthora ramorum in vitro. | until now gametangia have not been obtained between paired european a1 and american a2 isolates of phytopthora ramorum in vitro. their production in artificial culture relies on interspecific pairings. using p. drechsleri and p. cambivora testers, 51 of 110 p. ramorum isolates from across europe were all shown to be a1s; while 32 of 38 american isolates from across california and southwest oregon were shown to be a2s. however, these interspecific pairings are complex, unusually slow and unpredic ... | 2004 | 15446716 |
| is variation in susceptibility to phytophthora ramorum correlated with population genetic structure in coast live oak (quercus agrifolia)? | california coastal woodlands are suffering severe disease and mortality as a result of infection from phytophthora ramorum. quercus agrifolia is one of the major woodland species at risk. this study investigated within- and among-population variation in host susceptibility to inoculation with p. ramorum and compared this with population genetic structure using molecular markers. susceptibility was assessed using a branch-cutting inoculation test. trees were selected from seven natural population ... | 2005 | 15720634 |
| biological control of phytophthora ramorumon rhododendron. | phytophthora ramorum was found in poland in 2000 as the causal agent of rhododendron blight. besides eradication of diseased plants and rhododendron growing around, chemical and biological control of the pathogen is necessary. in this study in vitro activity of grapefruit extract and chitosan in the inhibition of p. ramorum growth and sporulation and their efficacy in the control of leaf and stem rot development was evaluated. amendment of v8 juice agar and soil leachate with grapefruit extract ... | 2004 | 15756859 |
| a transmembrane phospholipase d in phytophthora; a novel pld subfamily. | phospholipase d (pld) is a ubiquitous enzyme in eukaryotes that participates in various cellular processes. its catalytic domain is characterized by two hkd motifs in the c-terminal part. until now, two subfamilies were recognized based on their n-terminal domain structure. the first has a px domain in combination with a ph domain and is designated as pxph-pld. members of the second subfamily, named c2-pld, have a c2 domain and have, so far, only been found in plants. here we describe a novel pl ... | 2005 | 15826868 |
| examining the strength and possible causes of the relationship between fire history and sudden oak death. | fire can be a dominant process in the ecology of forest vegetation and can also affect forest disease dynamics. little is known about the relationship between fire and an emerging disease epidemic called sudden oak death, which is caused by a new pathogen, phytophthora ramorum. this disease has spread across a large, fire-prone portion of california, killing great numbers of oaks and tanoaks and infecting most associated woody plants. suitable hosts cover a much broader geographic range, raising ... | 2005 | 15891855 |
| phytophthora ramorum: integrative research and management of an emerging pathogen in california and oregon forests. | phytophthora ramorum, causal agent of sudden oak death, is an emerging plant pathogen first observed in north america associated with mortality of tanoak (lithocarpus densiflorus) and coast live oak (quercus agrifolia) in coastal forests of california during the mid-1990s. the pathogen is now known to occur in north america and europe and have a host range of over 40 plant genera. sudden oak death has become an example of unintended linkages between the horticultural industry and potential impac ... | 2005 | 16078887 |
| mosaic origin of the heme biosynthesis pathway in photosynthetic eukaryotes. | heme biosynthesis represents one of the most essential metabolic pathways in living organisms, providing the precursors for cytochrome prosthetic groups, photosynthetic pigments, and vitamin b(12). using genomic data, we have compared the heme pathway in the diatom thalassiosira pseudonana and the red alga cyanidioschyzon merolae to those of green algae and higher plants, as well as to those of heterotrophic eukaryotes (fungi, apicomplexans, and animals). phylogenetic analyses showed the mosaic ... | 2005 | 16093570 |
| characterization of a phytophthora mating hormone. | water molds of the genus phytophthora include many plant pathogens responsible for epidemics such as potato blight and sudden oak death, causing global economic damages. sexual reproduction is of biological importance in phytophthora and has been believed to be stimulated by unknown endogenous factors named a hormones. we describe here the chemical characterization of a phytophthora mating hormone, a1, which was obtained from approximately 2 tons of culture fluid of one mating type of a species ... | 2005 | 16166510 |
| characterisation of european and north american phytophthora ramorum isolates due to their morphology and mating behaviour in vitro with heterothallic phytophthora species. | vegetative growth rate, and size of sporangia, chlamydospores and oospores from 94 p. ramorum isolates were measured and the isolates were paired in vitro with four different heterothallic phytophthora species isolated from infected nursery plants in germany. p. ramorum isolates originated from different european countries and from canada and the usa. 66 of the 67 european isolates were determined as mating type a1; only one isolate was of mating type a2. of the 27 north american isolates tested ... | 2005 | 16175788 |
| ancient origin of elicitin gene clusters in phytophthora genomes. | the genus phytophthora belongs to the oomycetes in the eukaryotic stramenopile lineage and is comprised of over 65 species that are all destructive plant pathogens on a wide range of dicotyledons. phytophthora produces elicitins (elis), a group of extracellular elicitor proteins that cause a hypersensitive response in tobacco. database mining revealed several new classes of elicitin-like (ell) sequences with diverse elicitin domains in phytophthora infestans, phytophthora sojae, phytophthora bra ... | 2006 | 16237208 |
| on-site dna extraction and real-time pcr for detection of phytophthora ramorum in the field. | phytophthora ramorum is a recently described pathogen causing oak mortality (sudden oak death) in forests in coastal areas of california and southern oregon and dieback and leaf blight in a range of tree, shrub, and herbaceous species in the united states and europe. due to the threat posed by this organism, stringent quarantine regulations are in place, which restrict the movement of a number of hosts. fast and accurate diagnostic tests are required in order to characterize the distribution of ... | 2005 | 16269700 |
| computational and comparative analyses of 150 full-length cdna sequences from the oomycete plant pathogen phytophthora infestans. | phytophthora infestans is a devastating phytopathogenic oomycete that causes late blight on tomato and potato. recent genome sequencing efforts of p. infestans and other phytophthora species are generating vast amounts of sequence data providing opportunities to unlock the complex nature of pathogenesis. however, accurate annotation of phytophthora genomes will be a significant challenge. most of the information about gene structure in these species was gathered from a handful of genes resulting ... | 2006 | 16380277 |
| vmd: a community annotation database for oomycetes and microbial genomes. | the vbi microbial database (vmd) is a database system designed to host a range of microbial genome sequences. at present, the database contains genome sequence and annotation data of two plant pathogens phytophthora sojae and phytophthora ramorum. with the completion of the draft genome sequences of these pathogens in collaboration with the doe joint genome institute (jgi), we have created this resource to make the sequences publicly available. the genome sequences (95 mb for p.sojae and 65 mb f ... | 2006 | 16381891 |
| activation of zoosporogenesis-specific genes in phytophthora infestans involves a 7-nucleotide promoter motif and cold-induced membrane rigidity. | infections of plants by the oomycete phytophthora infestans typically result from zoospores, which develop from sporangia at cold temperatures. to help understand the relevant cold-induced signaling pathway, factors regulating the transcription of the zoosporogenesis-specific nif (nuclear lim-interactor-interacting factor) gene family were examined. sequences required for inducing pinifc3 were identified by analyzing truncated and mutated promoters using the beta-glucuronidase reporter in stable ... | 2006 | 16607021 |
| microsatellite markers identify three lineages of phytophthora ramorum in us nurseries, yet single lineages in us forest and european nursery populations. | analysis of 12 polymorphic simple sequence repeats identified in the genome sequence of phytophthora ramorum, causal agent of 'sudden oak death', revealed genotypic diversity to be significantly higher in nurseries (91% of total) than in forests (18% of total). our analysis identified only two closely related genotypes in us forests, while the genetic structure of populations from european nurseries was of intermediate complexity, including multiple, closely related genotypes. multilocus analysi ... | 2006 | 16629806 |
| the malarial host-targeting signal is conserved in the irish potato famine pathogen. | animal and plant eukaryotic pathogens, such as the human malaria parasite plasmodium falciparum and the potato late blight agent phytophthora infestans, are widely divergent eukaryotic microbes. yet they both produce secretory virulence and pathogenic proteins that alter host cell functions. in p. falciparum, export of parasite proteins to the host erythrocyte is mediated by leader sequences shown to contain a host-targeting (ht) motif centered on an rxlx (e, d, or q) core: this motif appears to ... | 2006 | 16733545 |
| demography and recruitment limitations of three oak species in california. | we review published studies on the demography and recruitment of california oak trees and focus on the widespread dominant species of the foothill woodlands, quercus douglasii, q. lobata, and q. agrifolia, to ascertain the nature and strength of evidence for a decline in populations of these species. the vast majority of studies have been of short duration (less than three years), focused on the acorn and seedling life stages, and conducted at few locations within each species geographic range. ... | 2006 | 16776062 |
| gene duplication event in family 12 glycosyl hydrolase from phytophthora spp. | a total of 18 paralogs of xyloglucan-specific endoglucanases (egls) from the glycosyl hydrolase family 12 were identified and characterized in phytophthora sojae and phytophthora ramorum. these genes encode predicted extracellular enzymes, with sizes ranging from 189 to 435 amino acid residues, that would be capable of hydrolyzing the xyloglucan component of the host cell wall. in two cases, four and six functional copies of these genes were found in tight succession within a region of 5 and 18 ... | 2006 | 16784880 |
| novel phosphatidylinositol phosphate kinases with a g-protein coupled receptor signature are shared by dictyostelium and phytophthora. | g-protein coupled receptors (gpcr) and phosphatidylinositol phosphate kinases (pipk) are important key switches in signal transduction pathways. a novel class of proteins was identified in the genomes of two unrelated organisms that harbor both a gpcr and a pipk domain. dictyostelium discoideum contains one gpcr-pipk, which is crucial in cell-density sensing, and the genomes of phytophthora sojae and phytophthora ramorum each encode twelve gpcr-pipks. intriguingly, these are currently the only s ... | 2006 | 16876997 |
| phytophthora genome sequences uncover evolutionary origins and mechanisms of pathogenesis. | draft genome sequences have been determined for the soybean pathogen phytophthora sojae and the sudden oak death pathogen phytophthora ramorum. oömycetes such as these phytophthora species share the kingdom stramenopila with photosynthetic algae such as diatoms, and the presence of many phytophthora genes of probable phototroph origin supports a photosynthetic ancestry for the stramenopiles. comparison of the two species' genomes reveals a rapid expansion and diversification of many protein fami ... | 2006 | 16946064 |
| composting is an effective treatment option for sanitization of phytophthora ramorum-infected plant material. | to determine the effects of heat and composting treatments on the viability of the plant pathogen phytophthora ramorum grown on both artificial and various natural substrates. | 2006 | 16968293 |
| growth and sporulation of phytophthora ramorum in vitro in response to temperature and light. | phytophthora ramorum, recently found in the us, is causing concern for hardwood forests and the nursery industry. in an effort to identify some of the environmental limitations to growth and sporulation we undertook a laboratory study of four us and three european (eu) isolates. on v8 media, isolates grew when incubated at 2-28 c and produced chlamydospores at 8-28 c. sporangia were produced at all temperatures tested: 10-30 c for us isolates and 6-26 c for eu isolates. optimal temperatures were ... | 2006 | 17040065 |
| stromata, sporangiomata and chlamydosori of phytophthora ramorum on inoculated mediterranean woody plants. | three types of multihyphal structures, stromata, sporangiomata and chlamydosori, are described for the plant pathogen phytophthora ramorum. their morphology, morphogenesis and position on the host organ were observed by dissecting, compound and scanning electron microscopy. stromata were consistently formed one to two weeks after zoospore inoculation of detached leaves and fruits of an assortment of mediterranean sclerophyll shrubs. stroma initials appeared subcuticularly or subepidermally and d ... | 2006 | 17059884 |
| multiple, non-allelic, intein-coding sequences in eukaryotic rna polymerase genes. | inteins are self-splicing protein elements. they are translated as inserts within host proteins that excise themselves and ligate the flanking portions of the host protein (exteins) with a peptide bond. they are encoded as in-frame insertions within the genes for the host proteins. inteins are found in all three domains of life and in viruses, but have a very sporadic distribution. only a small number of intein coding sequences have been identified in eukaryotic nuclear genes, and all of these a ... | 2006 | 17069655 |
| phytophthora foliorum sp. nov., a new species causing leaf blight of azalea. | a previously unknown phytophthora was recovered more than 60 times from evergreen hybrid azalea leaves collected during surveys for the sudden oak death pathogen phytophthora ramorum in california and tennessee. the novel phytophthora was discovered when genomic dna from this species cross-reacted with the its-based diagnostic pcr primers used to screen plants for the presence of p. ramorum. this species had caducous, semi-papillate sporangia, was homothallic with both paragynous and amphigynous ... | 2006 | 17070028 |
| expressed peptide tags: an additional layer of data for genome annotation. | while genome sequencing is becoming ever more routine, genome annotation remains a challenging process. identification of the coding sequences within the genomic milieu presents a tremendous challenge, especially for eukaryotes with their complex gene architectures. here, we present a method to assist the annotation process through the use of proteomic data and bioinformatics. mass spectra of digested protein preparations of the organism of interest were acquired and searched against a protein d ... | 2006 | 17081056 |
| a phytophthora infestans cystatin-like protein targets a novel tomato papain-like apoplastic protease. | there is emerging evidence that the proteolytic machinery of plants plays important roles in defense against pathogens. the oomycete pathogen phytophthora infestans, the agent of the devastating late blight disease of tomato (lycopersicon esculentum) and potato (solanum tuberosum), has evolved an arsenal of protease inhibitors to overcome the action of host proteases. previously, we described a family of 14 kazal-like extracellular serine protease inhibitors from p. infestans. among these, epi1 ... | 2007 | 17085509 |
| phytophthora genomics: the plant destroyers' genome decoded. | the year 2004 was an exciting one for the phytophthora research community. the united states department of energy joint genome institute (jgi) completed the draft genome sequence of two phytophthora species, phytophthora sojae and phytophthora ramorum. in august of that year over 50 people gathered at jgi in walnut creek, california, for an annotation jamboree and searched for the secrets and surprises that the two genomes have in petto. this culminated in a paper in science in september of this ... | 2006 | 17153913 |
| the repertoire of transfer rna genes is tuned to codon usage bias in the genomes of phytophthora sojae and phytophthora ramorum. | in all, 238 and 155 transfer (t)rna genes were predicted from the genomes of phytophthora sojae and p. ramorum, respectively. after omitting pseudogenes and undetermined types of trna genes, there remained 208 p. sojae trna genes and 140 p. ramorum trna genes. there were 45 types of trna genes, with distinct anticodons, in each species. fourteen common anticodon types of trnas are missing altogether from the genome in the two species; however, these appear to be compensated by wobbling of other ... | 2006 | 17153916 |
| extensive variation in nuclear mitochondrial dna content between the genomes of phytophthora sojae and phytophthora ramorum. | fragments of mitochondrial dna (mtdna) transferred to the nuclear genome are called nuclear mitochondrial dnas (numts). we report here a comparison of numt content between genomes from two species of the same genus. analysis of the genomes of phytophthora sojae and p. ramorum revealed large differences in the numt content of the two genomes: 16.27 x 10(-3) and 2.28 x 10(-3)% of each genome, respectively. substantial differences also exist between the two species in the sizes of the numts found i ... | 2006 | 17153917 |
| identification of cell wall-associated proteins from phytophthora ramorum. | the oomycete genus phytophthora comprises a large group of fungal-like plant pathogens. two phytophthora genomes recently have been sequenced; one of them is the genome of phytophthora ramorum, the causal agent of sudden oak death. during plant infection, extracellular proteins, either soluble secreted proteins or proteins associated with the cell wall, play important roles in the interaction with host plants. cell walls of p. ramorum contain 1 to 1.5% proteins, the remainder almost exclusively ... | 2006 | 17153919 |
| mitochondrial genome sequences and comparative genomics of phytophthora ramorum and p. sojae. | the sequences of the mitochondrial genomes of the oomycetes phytophthora ramorum and p. sojae were determined during the course of complete nuclear genome sequencing (tyler et al., science, 313:1261,2006). both mitochondrial genomes are circular mapping, with sizes of 39,314 bp for p. ramorum and 42,977 bp for p. sojae. each contains a total of 37 recognizable protein-encoding genes, 26 or 25 trnas (p. ramorum and p. sojae, respectively) specifying 19 amino acids, six more open reading frames (o ... | 2007 | 17310332 |
| a kingdom-specific protein domain hmm library for improved annotation of fungal genomes. | pfam is a general-purpose database of protein domain alignments and profile hidden markov models (hmms), which is very popular for the annotation of sequence data produced by genome sequencing projects. pfam provides models that are often very general in terms of the taxa that they cover and it has previously been suggested that such general models may lack some of the specificity or selectivity that would be provided by kingdom-specific models. | 2007 | 17425790 |
| faster, simpler, more-specific methods for improved molecular detection of phytophthora ramorum in the field. | phytophthora ramorum is the causal agent of sudden oak death. the pathogen also affects a wide range of tree, shrub, and herbaceous species in natural and landscaped environments as well as plants in the nursery industry. a taqman real-time pcr method for the detection of this pathogen in the field has been described previously; this paper describes the development of a number of assays based on this method which have various advantages for use in the field. a scorpion real-time pcr assay that i ... | 2007 | 17449689 |
| an exploratory study of the nutritional composition of tanoak (lithocarpus densiflorus) acorns after potassium phosphonate treatment. | native american pomo communities who live in the northern coastal range of california and consume acorns from tanoak trees as part of traditional diets are facing the potential loss of many culturally important trees to sudden oak death. pomo and other native american communities are reluctant to use the protective fungicide, potassium phosphonate, on trees used for acorn collection without information on how the treatment affects acorn properties. in this study, select macronutrients and polyph ... | 2007 | 17559226 |
| population dynamics of the sudden oak death pathogen phytophthora ramorum in oregon from 2001 to 2004. | phytophthora ramorum (oomycetes) is an emerging plant pathogen in forests in southwestern oregon (curry county). moreover, since 2003 it has been repeatedly isolated from plants in oregon nurseries. in this study, we analysed the genetic diversity of the p. ramorum population in oregon from 2001 to 2004 by using microsatellites. a total of 323 isolates (272 from the infested forest; 51 from nurseries) were screened at 10 loci. the overall p. ramorum population in oregon is characterized by low g ... | 2007 | 17614910 |
| adaptive evolution has targeted the c-terminal domain of the rxlr effectors of plant pathogenic oomycetes. | oomycete plant pathogens deliver effector proteins inside host cells to modulate plant defense circuitry and to enable parasitic colonization. these effectors are defined by a conserved motif, termed rxlr (for arg, any amino acid, leu, arg), that is located downstream of the signal peptide and that has been implicated in host translocation. because the phenotypes of rxlr effectors extend to plant cells, their genes are expected to be the direct target of the evolutionary forces that drive the an ... | 2007 | 17675403 |
| phenolic chemistry of coast live oak response to phytophthora ramorum infection. | since the mid 1990s, phytophthora ramorum has been responsible for the widespread mortality of tanoaks, as well as several oak species throughout california and oregon forests. however, not all trees die, even in areas with high disease pressure, suggesting that some trees may be resistant to the pathogen. in this study, the chemical basis of host resistance was investigated. three field experiments were carried out in california between december 2004 and september 2005. the levels of nine pheno ... | 2007 | 17713820 |
| rapid inventory of the ant assemblage in a temperate hardwood forest: species composition and assessment of sampling methods. | ants are key indicators of ecological change, but few studies have investigated how ant assemblages respond to dramatic changes in vegetation structure in temperate forests. pests and pathogens are causing widespread loss of dominant canopy tree species; ant species composition and abundance may be very sensitive to such losses. before the experimental removal of red oak trees to simulate effects of sudden oak death and examine the long-term impact of oak loss at the black rock forest (cornwall, ... | 2007 | 17716467 |
| tracking the sudden oak death pathogen. | invasive species are, by definition, unwelcome and pathogenic ones, especially so. tracing the origins and spread of phytophthora ramorum, the devastating 'sudden oak death' pathogen, in the forests and nurseries of oregon has revealed differences between forest and nursery pathogen populations that suggest discrete sources of primary inoculum initiate each type of outbreak. new information on the ecology and evolution of this pathogen is presented that helps gauge the effectiveness of quarantin ... | 2007 | 17850541 |
| antimicrobial activity of extractable conifer heartwood compounds toward phytophthora ramorum. | ethyl acetate extracts from heartwood of seven western conifer trees and individual volatile compounds in the extracts were tested for antimicrobial activity against phytophthora ramorum. extracts from incense and western redcedar exhibited the strongest activity, followed by yellow-cedar, western juniper, and port-orford-cedar with moderate activity, and no activity for douglas-fir and redwood extracts. chemical composition of the extracts varied both qualitatively and quantitatively among the ... | 2007 | 17929093 |
| correlation of isozyme profiles with genomic sequences of phytophthora ramorum and its p. sojae orthologues. | a correct interpretation of isozyme patterns can be seriously hampered by the lack of supporting genetic data. the availability of the complete genome sequence of phytophthora ramorum, enabled us to correlate isozyme profiles with the gene models predicted for these enzymes. thirty-nine p. ramorum strains were characterised employing isozyme analysis on malate dehydrogenase (mdh), nadp-dependent malic enzyme (mdhp), 6-phosphogluconate dehydrogenase (pgd), glucosephosphate isomerase (gpi) and lac ... | 2007 | 17968548 |
| genomic polymorphism of isolates of phytophthora ramorum from polish ornamental nurseries compared with other european and north american isolates. | we undertook an analysis of the genomic relationships between 15 isolates of phytophthora ramorum werres, de cock et man in't veld, obtained from symptomatic plants growing in polish ornamental nurseries, and 2 representatives of the european population and 3 of the north american population. dendrograms were generated by upgma based on 786 amplification products obtained in issr-pcr reactions. the representatives of the european population and 13 of the "polish" isolates formed a common cluster ... | 2007 | 17998602 |
| evolution of the cutinase gene family: evidence for lateral gene transfer of a candidate phytophthora virulence factor. | lateral gene transfer (lgt) can facilitate the acquisition of new functions in recipient lineages, which may enable them to colonize new environments. several recent publications have shown that gene transfer between prokaryotes and eukaryotes occurs with appreciable frequency. here we present a study of interdomain gene transfer of cutinases -- well documented virulence factors in fungi -- between eukaryotic plant pathogens phytophthora species and prokaryotic bacterial lineages. two putative c ... | 2008 | 18024004 |
| susceptibility to phytophthora ramorum in a key infectious host: landscape variation in host genotype, host phenotype, and environmental factors. | sudden oak death is an emerging forest disease caused by the invasive pathogen phytophthora ramorum. genetic and environmental factors affecting susceptibility to p. ramorum in the key inoculum-producing host tree umbellularia californica (bay laurel) were examined across a heterogeneous landscape in california, usa. laboratory susceptibility trials were conducted on detached leaves and assessed field disease levels for 97 host trees from 12 225-m(2) plots. genotype and phenotype characteristics ... | 2008 | 18069961 |
| phytophthora siskiyouensis, a new species from soil, water, myrtlewood (umbellularia californica) and tanoak (lithocarpus densiflorus) in southwestern oregon. | an unknown phytophthora species was recovered in southwestern oregon from rhododendron and tanoak leaf baits used for monitoring streams and soils for the presence of phytophthora ramorum, from a blighted shoot of myrtlewood and from tanoak bark cankers. isolates of this species yielded its-dna sequences that differed substantially from other phytophthora sequences in genbank. morphological features also differed from available descriptions of known phytophthora species. based on the combination ... | 2007 | 18268898 |
| cross-species global proteomics reveals conserved and unique processes in phytophthora sojae and phytophthora ramorum. | phytophthora ramorum and phytophthora sojae are destructive plant pathogens. p. sojae has a narrow host range, whereas p. ramorum has a wide host range. a global proteomics comparison of the vegetative (mycelium) and infective (germinating cyst) life stages of p. sojae and p. ramorum was conducted to identify candidate proteins involved in host range, early infection, and vegetative growth. sixty-two candidates for early infection, 26 candidates for vegetative growth, and numerous proteins that ... | 2008 | 18316789 |
| isolation and identification of rhizoxin analogs from pseudomonas fluorescens pf-5 by using a genomic mining strategy. | the products synthesized from a hybrid polyketide synthase/nonribosomal peptide synthetase gene cluster in the genome of pseudomonas fluorescens pf-5 were identified using a genomics-guided strategy involving insertional mutagenesis and subsequent metabolite profiling. five analogs of rhizoxin, a 16-member macrolide with antifungal, phytotoxic, and antitumor activities, were produced by pf-5, but not by a mutant with an insertion in the gene cluster. the five rhizoxin analogs, one of which had n ... | 2008 | 18344330 |
| influence of land-cover change on the spread of an invasive forest pathogen. | human-caused changes in land use and land cover have dramatically altered ecosystems worldwide and may facilitate the spread of infectious diseases. to address this issue, we examined the influence of land-cover changes between 1942 and 2000 on the establishment of an invasive pathogen, phytophthora ramorum, which causes the forest disease known as sudden oak death. we assessed effects of land-cover change, forest structure, and understory microclimate on measures of inoculum load and disease pr ... | 2008 | 18372563 |
| reconstruction of the sudden oak death epidemic in california through microsatellite analysis of the pathogen phytophthora ramorum. | the genetic structure of the clonally reproducing sudden oak death (sod) pathogen in california was investigated using seven variable microsatellites. a total of 35 multilocus genotypes were identified among 292 samples representative of populations from 14 forest sites and of the nursery trade. amova indicated significant genetic variability both within (44.34%) and among populations (55.66%). spatial autocorrelation analyses indicated that moran's index of similarity reached a minimum of 0.1 a ... | 2008 | 18444982 |
| forest health conditions in north america. | some of the greatest forest health impacts in north america are caused by invasive forest insects and pathogens (e.g., emerald ash borer and sudden oak death in the us), by severe outbreaks of native pests (e.g., mountain pine beetle in canada), and fires exacerbated by changing climate. ozone and n and s pollutants continue to impact the health of forests in several regions of north america. long-term monitoring of forest health indicators has facilitated the assessment of forest health and sus ... | 2008 | 18479794 |
| mitochondrial haplotype determination in the oomycete plant pathogen phytophthora ramorum. | the mitochondrial genome of an isolate of phytophthora ramorum from europe (eu) was sequenced and compared to the previously published genome sequence of an isolate from california (na). the eu mitochondrial genome had the identical gene order and encoded for the same suite of genes as the na mitochondrial genome, but had 13 single nucleotide polymorphisms (snps) and at 39,494 bp was 180 bp longer. this length difference was due to an increase in the size of the spacer region between the nad5 an ... | 2008 | 18488228 |
| early detection of emerging forest disease using dispersal estimation and ecological niche modeling. | distinguishing the manner in which dispersal limitation and niche requirements control the spread of invasive pathogens is important for prediction and early detection of disease outbreaks. here, we use niche modeling augmented by dispersal estimation to examine the degree to which local habitat conditions vs. force of infection predict invasion of phytophthora ramorum, the causal agent of the emerging infectious tree disease sudden oak death. we sampled 890 field plots for the presence of p. ra ... | 2008 | 18488603 |
| survival of phytophthora ramorum hyphae after exposure to temperature extremes and various humidities. | we examined the effect of short-term exposure to high and low temperatures and a range of relative humidity (rh) on survival of phytophthora ramorum hyphae. spore-free hyphal colonies were grown on dialysis squares atop v8 medium. colonies were transferred to water agar plates positioned at 27.5-50 c on a thermal gradient plate and incubated 2.5-480 min. for low temperature trials colonies were transferred to vials of distilled water and incubated in a water bath at -5 to -25 c for 1-24 h. in th ... | 2008 | 18592898 |
| influence of the medium-solidifying agent, the nutrient, and the genotype on the production of gametangia by phytophthora ramorum in vitro. | the effect of different parameters, including the type of nutrients, the quality of the gelling agent, and the genotype of the strain, were evaluated in the production of gametangia by phytophthora ramorum in vitro. by comparing different agar sources on a carrot-based medium, a delay or a failure in the production of oospores was observed in pairings carried out on media supplemented with technical agar. in contrast, oospores were produced on other agar types, the production on media supplement ... | 2009 | 18848885 |
| sources of inoculum for phytophthora ramorum in a redwood forest. | abstract sources of inoculum were investigated for dominant hosts of phytophthora ramorum in a redwood forest. infected trunks, twigs, and/or leaves of bay laurel (umbellularia californica), tanoak (lithocarpus densiflorus), and redwood (sequoia sempervirens) were tested in the laboratory for sporangia production. sporangia occurred on all plant tissues with the highest percentage on bay laurel leaves and tanoak twigs. to further compare these two species, field measurements of inoculum producti ... | 2008 | 18943203 |
| transmission of phytophthora ramorum in mixed-evergreen forest in california. | abstract during 2001 to 2003, the transmission biology of phytophthora ramorum, the causal agent of sudden oak death, was studied in mixedevergreen forest, a common forest type in northern, coastal california. investigation of the sources of spore production focused on coast live oak (quercus agrifolia) and bay laurel (umbellularia californica), dominant hosts that comprised 39.7 and 46.2% of the individuals at the study site, respectively. all tests for inoculum production from the surface of i ... | 2005 | 18943326 |
| real-time fluorescent polymerase chain reaction detection of phytophthora ramorum and phytophthora pseudosyringae using mitochondrial gene regions. | abstract a real-time fluorescent polymerase chain reaction (pcr) detection method for the sudden oak death pathogen phytophthora ramorum was developed based on mitochondrial dna sequence with an abi prism 7700 (taqman) sequence detection system. primers and probes were also developed for detecting p. pseudosyringae, a newly described species that causes symptoms similar to p. ramorum on certain hosts. the species-specific primer-probe systems were combined in a multiplex assay with a plant prime ... | 2006 | 18943415 |
| a rapid diagnostic test to distinguish between american and european populations of phytophthora ramorum. | abstract a new devastating disease in the united states, commonly known as sudden oak death, is caused by phytophthora ramorum. this pathogen, which previously was described attacking species of rhododendron and viburnum in germany and the netherlands, has established itself in forests on the central coast of california and is killing scores of native oak trees (lithocarpus densiflora, quercus agrifolia, q. kelloggii, and q. parvula var. shrevei). the phytosanitary authorities in the european un ... | 2004 | 18943486 |
| molecular detection of phytophthora ramorum, the causal agent of sudden oak death in california, and two additional species commonly recovered from diseased plant material. | abstract sudden oak death is a disease currently devastating forest ecosystems in several coastal areas of california. the pathogen causing this is phy-tophthora ramorum, although species such as p. nemorosa and p. pseudo-syringae often are recovered from symptomatic plants as well. a molecular marker system was developed based on mitochondrial sequences of the cox i and ii genes for detection of phytophthora spp. in general, and p. ramorum, p. nemorosa, and p. pseudosyringae in particular. the ... | 2004 | 18943487 |
| molecular detection of phytophthora ramorum by real-time polymerase chain reaction using taqman, sybr green, and molecular beacons. | abstract sudden oak death, caused by phytophthora ramorum, is a severe disease that affects many species of trees and shrubs. this pathogen is spreading rapidly and quarantine measures are currently in place to prevent dissemination to areas that were previously free of the pathogen. molecular assays that rapidly detect and identify p. ramorum frequently fail to reliably distinguish between p. ramorum and closely related species. to overcome this problem and to provide additional assays to incre ... | 2007 | 18943583 |
| detection, distribution, sporulation, and survival of phytophthora ramorum in a california redwood-tanoak forest soil. | abstract recovery of phytophthora ramorum from soils throughout sudden oak death-affected regions of california illustrates that soil may serve as an inoculum reservoir, but the role of soil inoculum in the disease cycle is unknown. this study addresses the efficacy of soil baiting, seasonal pathogen distribution under several epidemiologically important host species, summer survival and chlamydospore production in soil, and the impact of soil drying on pathogen survival. the efficacy of rhodode ... | 2007 | 18943696 |
| phytophthora ramorum colonizes tanoak xylem and is associated with reduced stem water transport. | abstract isolation, detection with diagnostic polymerase chain reaction (pcr), and microscopy demonstrated the presence of phytophthora ramorum in the sapwood of mature, naturally infected tanoak (lithocarpus densiflorus) trees. the pathogen was strongly associated with discolored sapwood (p < 0.001), and was recovered or detected from 83% of discolored sapwood tissue samples. hyphae were abundant in the xylem vessels, ray parenchyma, and fiber tracheids. chlamydospores were observed in the vess ... | 2007 | 18943716 |
| taqman chemistry for phytophthora ramorum detection and quantification, with a comparison of diagnostic methods. | abstract the choice of detection method for phytopathogens can be critically important in determining the success or failure of pest regulation systems. we present an assay for phytophthora ramorum that uses 5' fluorogenic exonuclease (taqman) chemistry to detect and quantify the pathogen from diseased tissue, and include a universal primer and probe set for an internal positive control. this method is sensitive, detecting as little as 15 fg of target dna when used in a nested design or 50 fg wh ... | 2006 | 18943749 |
| detection and quantification of phytophthora ramorum from california forests using a real-time polymerase chain reaction assay. | abstract the timely and accurate detection of pathogens is a critical aid in the study of the epidemiology and biology of plant diseases. in the case of regulated organisms, the availability of a sensitive and reliable assay is essential when trying to achieve early detection of the pathogen. we developed and tested a real-time, nested polymerase chain reaction (pcr) assay for the detection of phytophthora ramorum, causal agent of sudden oak death. this technique then was implemented as part of ... | 2004 | 18943796 |
| photosynthetic declines in phytophthora ramorum-infected plants develop prior to water stress and in response to exogenous application of elicitins. | abstract phytophthora ramorum, causal agent of sudden oak death, is responsible for widespread oak mortality in california and oregon, and has the potential to infect 100 or more species. symptoms range from stem girdling and shoot blight to leaf spotting. in this study, we examined the physiological impacts of p. ramorum infection on rhododendron macrophyllum. in stem-inoculated plants, photosynthetic capacity (v(cmax)) significantly declined by approximately 21% 3 weeks after inoculation in vi ... | 2007 | 18943934 |
| development of a one-step real-time polymerase chain reaction assay for diagnosis of phytophthora ramorum. | abstract phytophthora ramorum is a recently described pathogen causing bleeding cankers, dieback, and leaf blight on trees and shrubs in parts of europe and north america, where the disease is commonly known as sudden oak death. this article describes the development of a single-round real-time polymerase chain reaction (pcr) assay based on taqman chemistry, designed within the internal transcribed spacer 1 region of the nuclear ribosomal (nr)rna gene for detection of p. ramorum in plant materia ... | 2006 | 18944053 |
| diagnostic values and utility of immunological, morphological, and molecular methods for in planta detection of phytophthora ramorum. | abstract in this study, six methods for the detection of phytophthora ramorum in planta were compared using naturally infested rhododendron plant material. the methods included two immunological methods, one an enzyme-linked immunosorbent assay (elisa) and the other using a lateral flow format (lfd). three molecular tests based on the polymerase chain reaction (pcr) using taqman chemistry also were assessed, including two assays designed for specific detection of p. ramorum and one designed for ... | 2007 | 18944177 |
| phytophthora ramorum: a pathogen with a remarkably wide host range causing sudden oak death on oaks and ramorum blight on woody ornamentals. | phytophthora ramorum is an oomycete plant pathogen classified in the kingdom stramenopila. p. ramorum is the causal agent of sudden oak death on coast live oak and tanoak as well as ramorum blight on woody ornamental and forest understorey plants. it causes stem cankers on trees, and leaf blight or stem dieback on ornamentals and understorey forest species. this pathogen is managed in the usa and europe by eradication where feasible, by containment elsewhere and by quarantine in many parts of th ... | 2008 | 19019002 |
| aflps detect low genetic diversity for phytophthora nemorosa and p. pseudosyringae in the us and europe. | in california and oregon, two recently described oomycete forest pathogens, phytophthora nemorosa and p. pseudosyringae, overlap in their host and geographic ranges with the virulent p. ramorum, causal agent of "sudden oak death." epidemiological observations, namely broader geographic distribution and lack of landscape-level mortality, led to the hypothesis they are native to this region, whereas multiple lines of evidence indicate p. ramorum is exotic to north america. we used aflp analysis to ... | 2009 | 19061958 |
| evidence for the role of synchronicity between host phenology and pathogen activity in the distribution of sudden oak death canker disease. | variations in synchronicity between colonization rate by the pathogen and host phenology may account for unexplained spatial distribution of canker disease. the hypothesis that synchronous pathogenicity and host development are necessary for incidence of sudden oak death disease was tested by correlating seasonal variations in host cambial phenology and response to inoculation with phytophthora ramorum. response to infection was estimated by inoculating branch cuttings from coast live oak (querc ... | 2008 | 19086294 |
| ancient isolation and independent evolution of the three clonal lineages of the exotic sudden oak death pathogen phytophthora ramorum. | the genus phytophthora includes some of the most destructive plant pathogens affecting agricultural and native ecosystems and is responsible for a number of recent emerging and re-emerging infectious diseases of plants. sudden oak death, caused by the exotic pathogen p. ramorum, has caused extensive mortality of oaks and tanoaks in northern california, and has brought economic losses to us and european nurseries as well due to its infection of common ornamental plants. in its known range, p. ram ... | 2009 | 19222751 |
| evaluation of molecular markers for phytophthora ramorum detection and identification: testing for specificity using a standardized library of isolates. | given the importance of phytophthora ramorum from a regulatory standpoint, it is imperative that molecular markers for pathogen detection are fully tested to evaluate their specificity in detection of the pathogen. in an effort to evaluate 11 reported diagnostic techniques, we assembled a standardized dna library using accessions from the world phytophthora genetic resource collection for 315 isolates representing 60 described phytophthora spp. as well as 11 taxonomically unclassified isolates. ... | 2009 | 19271981 |
| proteins related to green algal striated fiber assemblin are present in stramenopiles and alveolates. | in green algae, striated fiber assemblin (sfa) is the major protein of the striated microtubule-associated fibers that are structural elements in the flagellar basal apparatus. using basic local alignment search tool (blast) searches of recently established databases, sfa-like sequences were detected in the genomes not only of green algal species but also of a range of other protists. these included species in two alveolate subgroups, the ciliates (tetrahymena thermophila, paramecium tetraurelia ... | 2009 | 19333716 |
| survival, dispersal, and potential soil-mediated suppression of phytophthora ramorum in a california redwood-tanoak forest. | because the role of soil inoculum of phytophthora ramorum in the sudden oak death disease cycle is not well understood, this work addresses survival, chlamydospore production, pathogen suppression, and splash dispersal of the pathogen in infested forest soils. colonized rhododendron and bay laurel leaf disks were placed in mesh sachets before transfer to the field in january 2005 and 2006. sachets were placed under tanoak, bay laurel, and redwood at three vertical locations: leaf litter surface, ... | 2009 | 19351257 |
| inventory and comparative evolution of the abc superfamily in the genomes of phytophthora ramorum and phytophthora sojae. | automated and manual annotation of the atp binding cassette (abc) superfamily in the phytophthora ramorum and p. sojae genomes has identified 135 and 136 members, respectively, indicating that this family is comparable in size to the arabidopsis thaliana and rice genomes, and significantly larger than that of two fungal pathogens, fusarium graminearum and magnaporthe grisea. the high level of synteny between these oomycete genomes extends to the abc superfamily, where 108 orthologues were identi ... | 2009 | 19407922 |
| migration patterns of the emerging plant pathogen phytophthora ramorum on the west coast of the united states of america. | phytophthora ramorum (oomycetes) is the causal agent of sudden oak death and ramorum blight on trees, shrubs, and woody ornamentals in the forests of coastal california and southwestern oregon and in nurseries of california, oregon, and washington. in this study, we investigated the genetic structure of p. ramorum on the west coast of the united states, focusing particularly on population differentiation potentially indicative of gene flow. in total, 576 isolates recovered from 2001 to 2005 were ... | 2009 | 19453234 |
| green fluorescent protein (gfp) as a reporter gene for the plant pathogenic oomycete phytophthora ramorum. | transgenic phytophthora ramorum strains that produce green fluorescent protein (gfp) constitutively were obtained after stable dna integration using a polyethylene glycol and caclâ‚‚-based transformation protocol. green fluorescent protein production was studied in developing colonies and in different propagules of the pathogen to evaluate its use in molecular and physiological studies. about 12% of the gfp transformants produced gfp to a level detectable by a confocal laser scanning microscope. g ... | 2009 | 19457053 |
| standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, phytophthora ramorum. | phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. however, in the recent literature there exists no consensus on naming of these lineages. here we propose a system for naming clonal lineages of p. ramorum based on a consensus established by the p. ramorum research community. clonal lineages are named with a two letter identifier for the c ... | 2009 | 19522576 |
| disease spread in small-size directed networks: epidemic threshold, correlation between links to and from nodes, and clustering. | network epidemiology has mainly focused on large-scale complex networks. it is unclear whether findings of these investigations also apply to networks of small size. this knowledge gap is of relevance for many biological applications, including meta-communities, plant-pollinator interactions and the spread of the oomycete pathogen phytophthora ramorum in networks of plant nurseries. moreover, many small-size biological networks are inherently asymmetrical and thus cannot be realistically modelle ... | 2009 | 19545575 |
| effect of temperature and moisture period on infection of rhododendron 'cunningham's white' by phytophthora ramorum. | we investigated the temperature and moisture conditions that allow phytophthora ramorum to infect rhododendron 'cunningham's white'. most experiments were performed with a single p. ramorum isolate from the na1 clonal lineage. for whole plants incubated in dew chambers at 10 to 31 degrees c, the greatest proportion of diseased leaves, 77.5%, occurred at the optimum temperature of 20.5 degrees c. disease occurred over the entire range of temperatures tested, although amounts of disease were minor ... | 2009 | 19671006 |
| population genetic analysis infers migration pathways of phytophthora ramorum in us nurseries. | recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. however, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. phytophthora ramorum is the exotic pathogen, discovered in the late 1990s, that is responsible for sudden oak death in california forests and ramorum blight of common ornamentals. the nursery trade has moved thi ... | 2009 | 19774068 |
| phytophthora ramorum does not cause physiologically significant systemic injury to california bay laurel, its primary reservoir host. | california bay laurel trees (umbellularia californica) play a crucial role in the reproduction and survival of phytophthora ramorum in coastal california forests by supporting sporulation during the rainy season and by providing a means for the pathogen to survive the dry, mediterranean summer. while bay laurel is thus critical to the epidemiology of sudden oak death and other p. ramorum diseases in california, the relatively minor symptoms observed on this reservoir host suggest that it may not ... | 2009 | 19821735 |
| genetic epidemiology of the sudden oak death pathogen phytophthora ramorum in california. | a total of 669 isolates of phytophthora ramorum, the pathogen responsible for sudden oak death, were collected from 34 californian forests and from the ornamental plant-trade. seven microsatellite markers revealed 82 multilocus genotypes (mgs) of which only three were abundant (>10%). iteratively collapsing based upon minimum phi(st), yielded five meta-samples and five singleton populations. populations in the same meta-sample were geographically contiguous, with one exception, possibly explaine ... | 2009 | 19840268 |
| are algal genes in nonphotosynthetic protists evidence of historical plastid endosymbioses? | how photosynthetic organelles, or plastids, were acquired by diverse eukaryotes is among the most hotly debated topics in broad scale eukaryotic evolution. the history of plastid endosymbioses commonly is interpreted under the "chromalveolate" hypothesis, which requires numerous plastid losses from certain heterotrophic groups that now are entirely aplastidic. in this context, discoveries of putatively algal genes in plastid-lacking protists have been cited as evidence of gene transfer from a ph ... | 2009 | 19843329 |
| optimization of control strategies for epidemics in heterogeneous populations with symmetric and asymmetric transmission. | there is growing interest in incorporating economic factors into epidemiological models in order to identify optimal strategies for disease control when resources are limited. in this paper we consider how to optimize the control of a pathogen that is capable of infecting multiple hosts with different rates of transmission within and between species. our objective is to find control strategies that maximize the discounted number of healthy individuals. we consider two classes of host-pathogen sy ... | 2010 | 19900466 |
| incidence of endornaviruses in phytophthora taxon douglasfir and phytophthora ramorum. | in this investigation, we show that four phytophthora taxon douglasfir isolates from the usa, irrespective of their geographical location or host plant, and 20% of a representative cohort of phytophthora ramorum isolates contain endornavirus dsrnas. three endornavirus-specific rt-pcr amplicons were generated by rt-pcr using dsrna isolated from the four phytophthora taxon douglasfir isolates and one representative phytophthora ramorum isolate as template with oligonucleotide primers designed from ... | 2010 | 19915969 |
| clonal expansion of the belgian phytophthora ramorum populations based on new microsatellite markers. | co-existence of both mating types a1 and a2 within the eu1 lineage of phytophthora ramorum has only been observed in belgium, which begs the question whether sexual reproduction is occurring. a collection of 411 belgian p. ramorum isolates was established during a 7-year survey. our main objectives were genetic characterization of this population to test for sexual reproduction, determination of population structure, evolution and spread, and evaluation of the effectiveness and impact of control ... | 2010 | 20002581 |
| rapid detection of phytophthora ramorum and p. kernoviae by two-minute dna extraction followed by isothermal amplification and amplicon detection by generic lateral flow device. | abstract a method for nucleic-acid-based detection of pathogens in plant material has been developed which comprises a simple and rapid method for extracting dna on the nitrocellulose membranes of lateral-flow devices, loop-mediated isothermal amplification (lamp) of target dna using labeled primers, and detection of the generically labeled amplification products by a sandwich immunoassay in a lateral-flow-device format. each of these steps can be performed without specialist equipment and is su ... | 2010 | 20055648 |
| a five-minute dna extraction method for expedited detection of phytophthora ramorum following prescreening using phytophthora spp. lateral flow devices. | in a direct comparison with established methods for phytophthora ramorum detection (isolation followed by morphological identification, or conventional dna extraction followed by taqman real-time pcr) a rapid, simplified detection method in which membranes of lateral flow devices (lfds) are added directly to taqman real-time pcr reactions was used to test 202 plant samples collected by plant health inspectors in the field. p. ramorum prevalence within the 202 samples was approximately 40% accord ... | 2010 | 20171248 |
| myosin diversity in the diatom phaeodactylum tricornutum. | this report describes the domain architecture of ten myosins cloned from the pennate diatom phaeodactylum tricornutum. several of the p. tricornutum myosins show similarity to myosins from the centric diatom thalassiosira pseudonana as well as to one myosin from the oomycete phytophthora ramorum. the p. tricornutum myosins, ranging in size from 126 kda to over 250 kda, all possess the canonical head, neck and tail domains common to most myosins, though variations in each of these domains is evid ... | 2010 | 20217677 |
| apparent competition in canopy trees determined by pathogen transmission rather than susceptibility. | epidemiological theory predicts that asymmetric transmission, susceptibility, and mortality within a community will drive pathogen and disease dynamics. these epidemiological asymmetries can result in apparent competition, where a highly infectious host reduces the abundance of less infectious or more susceptible members in a community via a shared pathogen. we show that the exotic pathogen phytophthora ramorum and resulting disease, sudden oak death, cause apparent competition among canopy tree ... | 2010 | 20391996 |