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Selected AbstractsAlternaria spp.: from general saprophyte to specific parasiteMOLECULAR PLANT PATHOLOGY, Issue 4 2003Bart P. H. J. Thomma SUMMARY Alternaria species are mainly saprophytic fungi. However, some species have acquired pathogenic capacities collectively causing disease over a broad host range. This review summarizes the knowledge on pathogenic strategies employed by the fungus to plunder the host. Furthermore, strategies employed by potential host plants in order to ward off an attack are discussed. Taxonomy:Alternaria spp. kingdom Fungi, subkingdom Eumycotera, phylum Fungi Imperfecti (a non-phylogenetic or artificial phylum of fungi without known sexual stages whose members may or may not be related; taxonomy does not reflect relationships), form class Hypomycetes, Form order Moniliales, form family Dematiaceae, genus Alternaria. Some species of Alternaria are the asexual anamorph of the ascomycete Pleospora while others are speculated to be anamorphs of Leptosphaeria. Host Range: Most Alternaria species are common saprophytes that derive energy as a result of cellulytic activity and are found in a variety of habitats as ubiquitous agents of decay. Some species are plant pathogens that cause a range of economically important diseases like stem cancer, leaf blight or leaf spot on a large variety of crops. Latent infections can occur and result in post-harvest diseases or damping-off in case of infected seed. Useful Website: Physiology and molecular aspects of Verticillium wilt diseases caused by V. dahliae and V. albo-atrumMOLECULAR PLANT PATHOLOGY, Issue 2 2006EMILIE F. FRADIN SUMMARY Introduction:,Verticillium spp. are soil-borne plant pathogens responsible for Verticillium wilt diseases in temperate and subtropical regions; collectively they affect over 200 hosts, including many economically important crops. There are currently no fungicides available to cure plants once they are infected. Taxonomy:, Kingdom: Fungi, phylum: Ascomycota, subphylum, Pezizomycotina, class: Sordariomycetes, order: Phyllachorales, genus: Verticillium. Host range and disease symptoms:, Over 200 mainly dicotyledonous species including herbaceous annuals, perennials and woody species are host to Verticillium diseases. As Verticillium symptoms can vary between hosts, there are no unique symptoms that belong to all plants infected by this fungus. Disease symptoms may comprise wilting, chlorosis, stunting, necrosis and vein clearing. Brown vascular discoloration may be observed in stem tissue cross-sections. Pathogenicity:,Verticillium spp. have been reported to produce cell-wall-degrading enzymes and phytotoxins that all have been implicated in symptom development. Nevertheless, evidence for a crucial role of toxins in pathogenicity is inconsistent and therefore not generally accepted. Microsclerotia and melanized mycelium play an important role in the disease cycle as they are a major inoculum source and are the primary long-term survival structures. Resistance:, Different defence responses in the prevascular and the vascular stage of Verticillium wilt diseases determine resistance. Although resistance physiology is well established, the molecular processes underlying this physiology remain largely unknown. Resistance against Verticillium largely depends on the isolation of the fungus in contained parts of the xylem tissues followed by subsequent elimination of the fungus. Although genetic resistance has been described in several plant species, only one resistance locus against Verticillium has been cloned to date. Useful website:,http://cbr-rbc.nrc-cnrc.gc.ca/services/cogeme/ [source] Tomato yellow leaf curl virus, the intracellular dynamics of a plant DNA virusMOLECULAR PLANT PATHOLOGY, Issue 1 2003Yedidya Gafni SUMMARY Tomato yellow leaf curl virus is a geminivirus, transmitted by whitefly ( Bemisia tabaci ) and causing the most destructive disease of tomato throughout the Mediterranean region, the Middle East and the tropical regions of Africa and Central America. Affected plants produce either no fruits or a few small fruits. Since it is an ssDNA virus which replicates in the host cell nucleus, the molecular mechanisms involved in the viral nuclear import have been the focus of our studies in recent years and results as well as prospects will be discussed. Taxonomy:Tomato yellow leaf curl virus (TYLCV) is a ssDNA plant virus, a member of the family Geminiviridae , of the genus Begomovirus. Physical properties: ,TYLCV, like all members of Geminiviridae, has geminate (twinned) particles, 18,20 nm in diameter, 30 nm long, apparently consisting of two incomplete T = 1 icosahedra joined together in a structure with 22 pentameric capsomers and 110 identical protein subunits (Fig. 1). Figure 1. Particles of TYLCV. Electron micrograph of purified, negatively stained TYLCV particles. Bar = 100 nm. Disease symptoms: ,Symptoms become visible in tomato in approximately 2,3 weeks after infection (Fig. 2). Leaf symptoms include chlorotic margins, small leaves that are cupped, thick and rubbery. The majority (up to 90%) of flowers abscise after infection, and therefore few fruits are produced. In Israel and elsewhere, weeds bridge the gap as potential perennial host and source of the virus between tomato growing seasons. Figure 2. Tomato yellow leaf curl symptoms on tomato plant. Leaves show yellowing on the edges accompanied by upward curling. Disease control: ,Control of TYLCV is currently based on insecticide treatments and/or physical barriers against the insect vector (Bemisia tabaci), and on tomato breeding programs based on introgression of resistance or tolerance from wild species to cultivated tomato. Useful website: , Moniliophthora perniciosa, the causal agent of witches' broom disease of cacao: what's new from this old foe?MOLECULAR PLANT PATHOLOGY, Issue 5 2008LYNDEL W. MEINHARDT SUMMARY Moniliophthora perniciosa (=Crinipellis perniciosa) causes one of the three main fungal diseases of Theobroma cacao (cacao), the source of chocolate. This pathogen causes Witches' broom disease (WBD) and has brought about severe economic losses in all of the cacao-growing regions to which it has spread with yield reductions that range from 50 to 90%. Cacao production in South America reflects the severity of this pathogen, as the yields in most of the infected regions have not returned to pre-outbreak levels, even with the introduction of resistant varieties. In this review we give a brief historical account and summarize the current state of knowledge focusing on developments in the areas of systematics, fungal physiology, biochemistry, genomics and gene expression in an attempt to highlight this disease. Moniliophthora perniciosa is a hemibiotrophic fungus with two distinct growth phases. The ability to culture a biotrophic-like phase in vitro along with new findings derived from the nearly complete genome and expression studies clearly show that these different fungal growth phases function under distinct metabolic parameters. These new findings have greatly improved our understanding of this fungal/host interaction and we may be at the crossroads of understanding how hemibiotrophic fungal plant pathogens cause disease in other crops. Historical summary of WBD:, The first WDB symptoms appear to have been described in the diaries of Alexandre Rodrigues Ferreira (described as lagartão; meaning big lizard) from his observations of cacao trees in 1785 and 1787 in Amazonia, which is consistent with the generally accepted idea that M. perniciosa, like its main host T. cacao, evolved in this region. The disease subsequently arrived in Surinam in 1895. WBD moved rapidly, spreading to Guyana in 1906, Ecuador in 1918, Trinidad in 1928, Colombia in 1929 and Grenada in 1948. In each case, cacao production was catastrophically affected with yield reductions of 50,90%. After the arrival of M. perniciosa in Bahia in 1989, Brazil went from being the world's 3rd largest producer of cacao (347 000 tonnes in 1988,1990; c. 15% of the total world production at that time) to a net importer (141 000 tonnes in 1998,2000). Fortunately for chocolate lovers, other regions of the world such as West Africa and South East Asia have not yet been affected by this disease and have expanded production to meet growing world demand (predicted to reach 3 700 000 tonnes by 2010). Classification:,Moniliophthora perniciosa (Stahel) Aime & Phillips-Mora: super-kingdom Eukaryota; kingdom Fungi; phylum Basidiomycota; subphylum Agaricomycotina; class Agaricomycetes; subclass Agaricomycetidae; order Agaricales; family Marasmiaceae; genus Moniliophthora. Useful websites:,http://www.lge.ibi.unicamp.br/vassoura/, http://nt.ars-grin.gov/taxadescriptions/keys/TrichodermaIndex.cfm, http://www.worldcocoafoundation.org/info-center/research-updates.asp, http://www.ars.usda.gov/ba/psi/spcl [source] Botrytis cinerea: the cause of grey mould diseaseMOLECULAR PLANT PATHOLOGY, Issue 5 2007BRIAN WILLIAMSON SUMMARY Introduction:,Botrytis cinerea (teleomorph: Botryotinia fuckeliana) is an airborne plant pathogen with a necrotrophic lifestyle attacking over 200 crop hosts worldwide. Although there are fungicides for its control, many classes of fungicides have failed due to its genetic plasticity. It has become an important model for molecular study of necrotrophic fungi. Taxonomy:, Kingdom: Fungi, phylum: Ascomycota, subphylum: Pezizomycotina, class: Leotiomycetes, order: Helotiales, family: Sclerotiniaceae, genus: Botryotinia. Host range and symptoms: Over 200 mainly dicotyledonous plant species, including important protein, oil, fibre and horticultural crops, are affected in temperate and subtropical regions. It can cause soft rotting of all aerial plant parts, and rotting of vegetables, fruits and flowers post-harvest to produce prolific grey conidiophores and (macro)conidia typical of the disease. Pathogenicity:,B. cinerea produces a range of cell-wall-degrading enzymes, toxins and other low-molecular-weight compounds such as oxalic acid. New evidence suggests that the pathogen triggers the host to induce programmed cell death as an attack strategy. Resistance:, There are few examples of robust genetic host resistance, but recent work has identified quantitative trait loci in tomato that offer new approaches for stable polygenic resistance in future. Useful websites:,http://www.phi-base.org/query.php, http://www.broad.mit.edu/annotation/genome/botrytis_cinerea/Home.html, http://urgi.versailles.inra.fr/projects/Botrytis/, http://cogeme.ex.ac.uk [source] Cladosporium fulvum (syn. Passalora fulva), a highly specialized plant pathogen as a model for functional studies on plant pathogenic MycosphaerellaceaeMOLECULAR PLANT PATHOLOGY, Issue 4 2005BART P. H. J. THOMMA SUMMARY Taxonomy:,Cladosporium fulvum is an asexual fungus for which no sexual stage is currently known. Molecular data, however, support C. fulvum as a member of the Mycosphaerellaceae, clustering with other taxa having Mycosphaerella teleomorphs. C. fulvum has recently been placed in the anamorph genus Passalora as P. fulva. Its taxonomic disposition is supported by its DNA phylogeny, as well as the distinct scars on its conidial hila, which are typical of Passalora, and unlike Cladosporium s.s., which has teleomorphs that reside in Davidiella, and not Mycosphaerella. Host range and disease symptoms:, The presently known sole host of C. fulvum is tomato (members of the genusLycopersicon). C. fulvum is mainly a foliar pathogen. Disease symptoms are most obvious on the abaxial side of the leaf and include patches of white mould that turn brown upon sporulation. Due to stomatal clogging, curling of leaves and wilting can occur, leading to defoliation. C. fulvum as a model pathogen:, The interaction between C. fulvum and tomato is governed by a gene-for-gene relationship. A total of eight Avr and Ecp genes, and for four of these also the corresponding plant Cf genes, have been cloned. Obtaining conclusive evidence for gene-for-gene relationships is complicated by the poor availability of genetic tools for most Mycosphaerellaceae,plant interactions. Newly developed tools, including Agrobacterium -mediated transformation and RNAi, added to the genome sequence of its host tomato, which will be available within a few years, render C. fulvum attractive as a model species for plant pathogenic Mycosphaerellaceae. Useful websites:,http://www.sgn.cornell.edu/help/about/index.html; http://cogeme.ex.ac.uk [source] The stem canker (blackleg) fungus, Leptosphaeria maculans, enters the genomic eraMOLECULAR PLANT PATHOLOGY, Issue 3 2005T. ROUXEL SUMMARY Leptosphaeria maculans is the most ubiquitous pathogen of Brassica crops, and mainly oilseed brassicas (oilseed rape, canola), causing the devastating ,stem canker' or ,blackleg'. This review summarizes our current knowledge on the pathogen, from taxonomic issues to specific life traits. It mainly illustrates the importance of formal genetics approaches on the pathogen side to dissect the interaction with the host plants. In addition, this review presents the main current research topics on L. maculans and focuses on the L. maculans genome initiative recently begun, including its main research issues. Taxonomy:,Leptosphaeria maculans (Desm.) Ces. & de Not. (anamorph Phoma lingam Tode ex Fr.). Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes (Loculoascomycetes), Order Pleosporales, Genus Leptosphaeria, Species maculans. Host range:, cultivated Brassicas such as Brassica napus (oilseed rape, canola), B. rapa, B. juncea, B. oleracea, etc., along with numerous wild crucifers species. Arabidopsis thaliana was recently reported to be a potential host for L. maculans. Primary disease symptoms are greyish-green collapse of cotyledon or leaf tissue, without a visible margin, bearing tiny black spots (pycnidia). The fungus then develops an endophytic symptomless growth for many months. Secondary symptoms, at the end of the growing season, are dry necroses of the crown tissues with occasional blackening (stem canker or blackleg) causing lodging of the plants. Pseudothecia differentiate on leftover residues. Seedling damping-off and premature ripening are also reported under certain environmental conditions. Useful websites:,Leptosphaeria maculans sequencing project at Genoscope: http://www.genoscope.cns.fr/externe/English/Projets/Projet_DM/organisme_DM.html; the SECURE site: http://www.secure.rothamsted.ac.uk/ the ,Blackleg' group at the University of Melbourne: http://www.botany.unimelb.edu.au/blackleg/overview.htm [source] Xanthomonas axonopodis pv. citri: factors affecting successful eradication of citrus cankerMOLECULAR PLANT PATHOLOGY, Issue 1 2004James H. Graham SUMMARY Taxonomic status:, Bacteria, Proteobacteria, gamma subdivision, Xanthomodales, Xanthomonas group, axonopodis DNA homology group, X. axonopodis pv. citri (Hasse) Vauterin et al. Microbiological properties:, Gram negative, slender, rod-shaped, aerobic, motile by a single polar flagellum, produces slow growing, non-mucoid colonies in culture, ecologically obligate plant parasite. Host range:, Causal agent of Asiatic citrus canker on most Citrus spp. and close relatives of Citrus in the family Rutaceae. Disease symptoms:, Distinctively raised, necrotic lesions on fruits, stems and leaves. Epidemiology:, Bacteria exude from lesions during wet weather and are disseminated by splash dispersal at short range, windblown rain at medium to long range and human assisted movement at all ranges. Crop loss:, Severe infections cause defoliation, blemished fruit, premature fruit drop, die-back of twigs and general debilitation of the tree. Distribution:, Citrus canker is not present in all subtropical to tropical regions of citriculture in the world, so considerable regulatory efforts are expended to prevent the introduction and spread of X. axonopodis pv. citri into areas in the Americas, Australia and elsewhere, with climates conducive to the disease. Importance:, Limited strategies exist for suppression of citrus canker on more susceptible cultivars. Blemished fruit are unmarketable and exposed fruit are restricted in market access. The economic impact of loss of markets is much greater than that from yield and quality reductions of the crop. Useful websites:,http://doacs.state.fl.us/canker , http://www.apsnet.org/education/lessonsplantpath/citruscanker/top.htm , http://www.apsnet.org/online/feature/citruscanker/ , http://www.plantmanagementnetwork.org/pub/php/review/citruscanker/ , http://www.abecitrus.com.br/fundecitrus.html , http://www.biotech.ufl.edu/PlantContainment/canker.htm , http://www.aphis.usda.gov/oa/ccanker/ . [source] Fusarium oxysporum: exploring the molecular arsenal of a vascular wilt fungusMOLECULAR PLANT PATHOLOGY, Issue 5 2003Antonio Di Pietro SUMMARY Taxonomy: Vascular wilt fungus; Ascomycete although sexual stage is yet to be found. The most closely related teleomorphic group, Gibberella, is classified within the Pyrenomycetes. Host range: Very broad at the species level. More than 120 different formae speciales have been identified based on specificity to host species belonging to a wide range of plant families. Disease symptoms: Initial symptoms of vascular wilt include vein clearing and leaf epinasty, followed by stunting, yellowing of the lower leafs, progressive wilting of leaves and stem, defoliation and finally death of the plant. In cross-sections of the stem, a brown ring is evident in the area of the vascular bundles. Some formae speciales are not primarily vascular pathogens but cause foot- and rootrot or bulbrot. Economic importance: Causes severe losses on most vegetables and flowers, several field crops such as cotton and tobacco, plantation crops such as banana, plantain, coffee and sugarcane, and a few shade trees. Control: Use of resistant varieties is the only practical measure for controlling the disease in the field. Under greenhouse conditions, soil sterilization can be performed. Alternative control methods with potential for the future include soil solarization and biological control with antagonistic bacteria or fungi. Useful websites: http://www.fgsc.net/fus.htm, http://www-genome.wi.mit.edu/annotation/fungi/fusarium/, http://www.cbs.knaw.nl/fusarium/database.html [source] Xanthomonas citri: breaking the surfaceMOLECULAR PLANT PATHOLOGY, Issue 3 2003Asha M. Brunings SUMMARY Taxonomy: Bacteria; Proteobacteria, Gammaproteobacteria; Xanthomonadales; Xanthomonadaceae, Xanthomonas. Microbiological properties: Gram-negative, obligately aerobic, straight rods, motile by a single polar flagellum, yellow pigment. Related species:X. campestris , X. axonopodis , X. oryzae , X. albilineans . Host range: Affects Rutaceous plants, primarily Citrus spp., Fortunella spp., and Poncirus spp., world-wide. Quarantined pathogen in many countries. Economically important hosts are cultivated orange, grapefruit, lime, lemon, pomelo and citrus rootstock. Disease symptoms: On leaves, first appearance is as oily looking, 2,10 mm, similarly sized, circular spots, usually on the abaxial surface. On leaves, stems, thorns and fruit, circular lesions become raised and blister-like, growing into white or yellow spongy pustules. These pustules then darken and thicken into a light tan to brown corky canker, which is rough to the touch. On stems, pustules may coalesce to split the epidermis along the stem length, and occasionally girdling of young stems may occur. Older lesions on leaves and fruit tend to have more elevated margins and are at times surrounded by a yellow chlorotic halo (that may disappear) and a sunken centre. Sunken craters are especially noticeable on fruit, but the lesions do not penetrate far into the rind. Defoliation and premature abscission of affected fruit occurs on heavily infected trees. Useful websites: Soft rot erwiniae: from genes to genomesMOLECULAR PLANT PATHOLOGY, Issue 1 2003Ian K. Toth SUMMARY The soft rot erwiniae, Erwinia carotovora ssp. atroseptica (Eca), E. carotovora ssp. carotovora (Ecc) and E. chrysanthemi (Ech) are major bacterial pathogens of potato and other crops world-wide. We currently understand much about how these bacteria attack plants and protect themselves against plant defences. However, the processes underlying the establishment of infection, differences in host range and their ability to survive when not causing disease, largely remain a mystery. This review will focus on our current knowledge of pathogenesis in these organisms and discuss how modern genomic approaches, including complete genome sequencing of Eca and Ech, may open the door to a new understanding of the potential subtlety and complexity of soft rot erwiniae and their interactions with plants. Taxonomy: ,The soft rot erwiniae are members of the Enterobacteriaceae, along with other plant pathogens such as Erwinia amylovora and human pathogens such as Escherichia coli, Salmonella spp. and Yersinia spp. Although the genus name Erwinia is most often used to describe the group, an alternative genus name Pectobacterium was recently proposed for the soft rot species. Host range:,Ech mainly affects crops and other plants in tropical and subtropical regions and has a wide host range that includes potato and the important model host African violet ( Saintpaulia ionantha ). Ecc affects crops and other plants in subtropical and temperate regions and has probably the widest host range, which also includes potato. Eca , on the other hand, has a host range limited almost exclusively to potato in temperate regions only. Disease symptoms: ,Soft rot erwiniae cause general tissue maceration, termed soft rot disease, through the production of plant cell wall degrading enzymes. Environmental factors such as temperature, low oxygen concentration and free water play an essential role in disease development. On potato, and possibly other plants, disease symptoms may differ, e.g. blackleg disease is associated more with Eca and Ech than with Ecc. Useful websites: ,http://www.scri.sari.ac.uk/TiPP/Erwinia.htm, http://www.ahabs.wisc.edu:16080/pernalab/erwinia/index.htm, http://www.tigr.org/tdb/mdb/mdbinprogress.html, http://www.sanger.ac.uk/Projects/E_carotovora/. [source] Public library websites for teenagers: How are they addressing the consumer health information needs of today's teens?PROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2007Jennifer E. Burke Young adult use of the Web both for creating and reviewing content continues to grow and the Internet has become an important tool for teenagers seeking health information (Borzekowski & Rickert 2001, Gray et al 2005; Rideout 2001; Richardson 2002; Vargas 2005). More than 70 percent of 15 to 17 year olds say they have used the Internet to look up health information (Rideout 2001, Richardson et al 2002). In fact, the Kaiser Family Foundation study reported in "Generation Rx.com" found that more youth had looked for health information than had engaged in various Web 2.0 behaviors as purchasing something online or using a chat room (Rideout 2001). Researchers cite availability, anonymity, and affordability as the key reasons teenagers turn to the web for answers to their health-related questions (Barak & Fisher 2001; Gray et al 2005). While the Internet provides teenagers with access to a wealth of health-related resources, it also presents challenges that can negatively impact the ability of adolescents to access quality information online. Difficulty conducting searches, judging the credibility of the information retrieved, and accessing sites due to filtering software are just a few of the barriers teenagers face (Gray et al 2002; Gray et al 2005; Richardson et al 2002). Like many Web users, teenagers also express concerns about privacy and confidentiality, especially in chat rooms or email correspondences (Vargas 2005). Given the issues teens face when searching for health information online, it seems natural that public libraries take the lead in providing assistance to teenagers who need help finding health information. Libraries, particularly public libraries, have a long history of providing consumer heath information to adults in their communities, and this service has transitioned online as libraries provide Internet access to electronic consumer health information (Smith 2006). In addition, many public libraries have developed websites specifically for teenagers. As more teens look for personalized information or the ability to ,create' their own content, these library web pages often serve as centers for reference, educational support, popular materials, community information, and library programming (Hughes-Hassell & Miller 2003; Jones 1997). Including links to useful websites would alleviate some of the frustration teenagers face when searching for quality health information on the Internet and allow them to make their own informed decisions (Vargas 2005). But how common is it for these web pages to provide consumer health information for teenagers? [source] CREATING YOUR OWN CONSULTING BUSINESSANNALS OF ANTHROPOLOGICAL PRACTICE, Issue 1 2008Carla N. Littlefield As academic positions become more competitive, many anthropologists are exploring the possibilities for creating their own consulting businesses. However, entrepreneurship is not a topic usually taught in graduate anthropology programs. In this article, two anthropologists provide advice on starting and operating a consulting business. The purpose of this article is to acquaint the budding professional with the basics of starting and operating a small business based on the skills, educational background, and experience of a professional anthropologist. The first part, Small Business Start-Up, describes the process of creating a business, from conducting a self-assessment to developing a plan to promote your services. The second part, Operating the Small Business, provides several frameworks for delivering good consultant services, from understanding the consulting process to an introduction to project management. Anthropologists are trained in data collection, analysis, and interpretation. We may also receive instruction on research design and how to conduct fieldwork and research. Our anthropological training in observing and understanding the beliefs and behaviors of groups, as well as seeing things from the client's unique perspective, gives us an edge as consultants. Our training helps us work in other cultural settings, and to work with different groups and subgroups. The authors emphasize networking as a fundamental promotion strategy that can take place at professional meetings (local, regional, or national) or with community organizations relevant to one's business (organizations, foundations, or coalitions). This article includes several useful websites for start-up topics and for networking with other anthropologists. [source]
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