- Home
- A-Z Publications
- Annual Review of Phytopathology
- Previous Issues
- Volume 42, 2004
Annual Review of Phytopathology - Volume 42, 2004
Volume 42, 2004
-
-
The Accidental Plant Pathologist
Vol. 42 (2004), pp. 1–12More Less▪ AbstractThis article presents the experiences of a woman in academic plant pathology from the 1950s to today. Topics include the social climate for women in science, personal and professional developments and research discoveries, public policy issues in agriculture and biotechnology affecting plant pathology, and projections for the future of plant pathology.
-
-
-
TOBACCO MOSAIC VIRUS: A Model System for Plant Biology
Vol. 42 (2004), pp. 13–34More Less▪ AbstractTobacco mosaic virus (TMV) has had an illustrious history for more than 100 years, dating to Beijerinck's description of the mosaic disease of tobacco as a contagium vivum fluidum and the modern usage of the word “virus.” Since then, TMV has been acknowledged as a preferred didactic model and a symbolic model to illuminate the essential features that define a virus. TMV additionally emerged as a prototypic model to investigate the biology of host plants, namely tobacco. TMV also exemplifies how a model system furthers novel, and often unexpected, developments in biology and virology. Today, TMV is used as a tool to study host-pathogen interactions and cellular trafficking, and as a technology to express valuable pharmaceutical proteins in tobacco. The history of TMV illustrates how pragmatic strategies to control an economically important disease of tobacco have had unexpected and transforming effects across platforms that impinge on plant health and public health.
Tobacco mosaic virus: An RNA virus that causes mosaic disease in tobacco and similar effects in other plants, much used as an experimental subject; abbrev. TMV. (8)
-
-
-
ASSESSMENT AND MANAGEMENT OF SOIL MICROBIAL COMMUNITY STRUCTURE FOR DISEASE SUPPRESSION1
Vol. 42 (2004), pp. 35–59More Less▪ AbstractIdentification of the biological properties contributing to the function of suppressive soils is a necessary first step to the management of such systems for use in the control of soilborne diseases. The development and application of molecular methods for the characterization and monitoring of soil microbial properties will enable a more rapid and detailed assessment of the biological nature of soil suppressiveness. Although suppressive soils have provided a wealth of microbial resources that have subsequently been applied for the biological control of soilborne plant pathogens, the full functional capabilities of the phenomena have not been realized in production agricultural ecosystems. Cultural practices, such as the application of soil amendments, have the capacity to enhance disease suppression, though the biological modes of action may vary from that initially resident to the soil. Plants have a distinct impact on characteristics and activity of resident soil microbial communities, and therefore play an important role in determining the development of the disease-suppressive state. Likewise, plant genotype will modulate these same biological communities, and should be considered when developing strategies to exploit the potential of such a natural disease control system. Implementation of consistently effective practices to manage this resource in an economically and environmentally feasible manner will require more detailed investigation of these biologically complex systems and refinement of currently available methodologies.
-
-
-
ANALYSIS OF DISEASE PROGRESS AS A BASIS FOR EVALUATING DISEASE MANAGEMENT PRACTICES
Vol. 42 (2004), pp. 61–82More Less▪ AbstractThe relationship between epidemiology and disease management is long-standing but sometimes tenuous. It may seem self-evident that improved understanding of epidemic processes will lead to more effective control practices but this remains a testable proposition rather than demonstrated reality. A wide range of models differing in mathematical sophistication and computational complexity has been proposed as a means of achieving a greater understanding of epidemiology and carrying this through to improved management. The potential exists to align these modeling approaches to evaluation of control practices and prediction of the consequent epidemic outcomes, but these have yet to make a major impact on practical disease management. For the immediate future simpler pragmatic approaches for analysis of disease progress, using nonlinear growth functions and/or integrated measures such as area under disease progress curves, will play a key role in informing tactical and strategic decisions on control treatments. These approaches have proved useful in describing control effectiveness and, in some cases, optimizing or changing control practices.
-
-
-
EVOLUTION OF PLANT PARASITISM AMONG NEMATODES
Vol. 42 (2004), pp. 83–105More Less▪ AbstractDespite extraordinary diversity of free-living species, a comparatively small fraction of nematodes are parasites of plants. These parasites represent at least three disparate clades in the nematode tree of life, as inferred from rRNA sequences. Plant parasites share functional similarities regarding feeding, but many similarities in feeding structures result from convergent evolution and have fundamentally different developmental origins. Although Tylenchida rRNA phylogenies are not fully resolved, they strongly support convergent evolution of sedentary endoparasitism and plant nurse cells in cyst and root-knot nematodes. This result has critical implications for using model systems and genomics to identify and characterize parasitism genes for representatives of this clade. Phylogenetic studies reveal that plant parasites have rich and complex evolutionary histories that involve multiple transitions to plant parasitism and the possible use of genes obtained by horizontal transfer from prokaryotes. Developing a fuller understanding of plant parasitism will require integrating more comprehensive and resolved phylogenies with appropriate choices of model organisms and comparative evolutionary methods.
-
-
-
LESSONS LEARNED FROM THE GENOME ANALYSIS OF RALSTONIA SOLANACEARUM
Vol. 42 (2004), pp. 107–134More Less▪ AbstractRalstonia solanacearum is a devastating plant pathogen with a global distribution and an unusually wide host range. This bacterium can also be free-living as a saprophyte in water or in the soil in the absence of host plants. The availability of the complete genome sequence from strain GMI1000 provided the basis for an integrative analysis of the molecular traits determining the adaptation of the bacterium to various environmental niches and pathogenicity toward plants. This review summarizes current knowledge and speculates on some key bacterial functions, including metabolic versatility, resistance to metals, complex and extensive systems for motility and attachment to external surfaces, and multiple protein secretion systems. Genome sequence analysis provides clues about the evolution of essential virulence genes such as those encoding the Type III secretion system and related pathogenicity effectors. It also provided insights into possible mechanisms contributing to the rapid adaptation of the bacterium to its environment in general and to its interaction with plants in particular.
-
-
-
MANAGEMENT AND RESISTANCE IN WHEAT AND BARLEY TO FUSARIUM HEAD BLIGHT1
Guihua Bai, and Gregory ShanerVol. 42 (2004), pp. 135–161More Less▪ AbstractFusarium head blight (FHB) is a devastating disease of wheat and barley worldwide. Resistant cultivars could reduce damage from FHB. Chinese wheat cultivar Sumai 3 and its derivatives represent the greatest degree of resistance to FHB known. A major quantitative trait locus (QTL) on chromosome 3BS and other minor QTL for FHB resistance have been identified in these cultivars and used in wheat-breeding programs worldwide. Many breeding lines with the 3BS resistance QTL and improved agronomic traits have been developed. In barley, only limited sources of FHB resistance are available, especially in six-rowed barley, and none of them contains a DON level low enough to meet the safety requirement of the brewing industry. Several QTL have been identified for lower FHB severity, DON content, and kernel discoloration and used to enhance FHB resistance in barley. Marker-assisted selection for FHB resistance QTL on 3BS of wheat and on 2H of barley is in progress.
-
-
-
COMPARATIVE GENOMICS ANALYSES OF CITRUS-ASSOCIATED BACTERIA
Vol. 42 (2004), pp. 163–184More Less▪ AbstractXylella fastidiosa 9a5c (XF-9a5c) and Xanthomonas axonopodis pv. citri (XAC) are bacteria that infect citrus plants. Sequencing of the genomes of these strains is complete and comparative analyses are now under way with the genomes of other bacteria of the same genera. In this review, we present an overview of this comparative genomic work. We also present a detailed genomic comparison between XF-9a5a and XAC. Based on this analysis, genes and operons were identified that might be relevant for adaptation to citrus. XAC has two copies of a type II secretion system, a large number of cell wall–degrading enzymes and sugar transporters, a complete energy metabolism, a whole set of avirulence genes associated with a type III secretion system, and a complete flagellar and chemotatic system. By contrast, XF-9a5c possesses more genes involved with type IV pili biosynthesis than does XAC, contains genes encoding for production of colicins, and has 4 copies of Type I restriction/modification system while XAC has only one.
-
-
-
SYSTEMIC ACQUIRED RESISTANCE
W.E. Durrant, and X. DongVol. 42 (2004), pp. 185–209More Less▪ AbstractSystemic acquired resistance (SAR) is a mechanism of induced defense that confers long-lasting protection against a broad spectrum of microorganisms. SAR requires the signal molecule salicylic acid (SA) and is associated with accumulation of pathogenesis-related proteins, which are thought to contribute to resistance. Much progress has been made recently in elucidating the mechanism of SAR. Using the model plant Arabidopsis, it was discovered that the isochorismate pathway is the major source of SA during SAR. In response to SA, the positive regulator protein NPR1 moves to the nucleus where it interacts with TGA transcription factors to induce defense gene expression, thus activating SAR. Exciting new data suggest that the mobile signal for SAR might be a lipid molecule. We discuss the molecular and genetic data that have contributed to our understanding of SAR and present a model describing the sequence of events leading from initial infection to the induction of defense genes.
-
-
-
MOLECULAR ASPECTS OF PLANT VIRUS TRANSMISSION BY OLPIDIUM AND PLASMODIOPHORID VECTORS
Vol. 42 (2004), pp. 211–241More Less▪ AbstractThe genome structures of a large number of viruses transmitted by olpidium and plasmodiophorid vectors have been determined. The viruses are highly diverse, belonging to 12 genera in at least 4 families. Plasmodiophorids are now classified as protists rather than true fungi. This finding, along with the recognition of the great variety of viruses transmitted by olpidium and plasmodiophorid vectors, will likely lead to an elaboration of the details of in vitro and in vivo transmission mechanisms. Recent progress in elucidating the interaction between Cucumber necrosis virus (CNV) and its zoospore vector suggests that specific sites on the capsid as well as on the zoospore are involved in transmission. Moreover, some features of CNV/zoospore attachment are similar to poliovirus/host cell interactions, suggesting evolutionary conservation of functional features of plant and animal virus capsids.
-
-
-
MICROBIAL DIVERSITY IN SOIL: Selection of Microbial Populations by Plant and Soil Type and Implications for Disease Suppressiveness
Vol. 42 (2004), pp. 243–270More Less▪ AbstractAn increasing interest has emerged with respect to the importance of microbial diversity in soil habitats. The extent of the diversity of microorganisms in soil is seen to be critical to the maintenance of soil health and quality, as a wide range of microorganisms is involved in important soil functions. This review focuses on recent data relating how plant type, soil type, and soil management regime affect the microbial diversity of soil and the implication for the soil's disease suppressiveness. The two main drivers of soil microbial community structure, i.e., plant type and soil type, are thought to exert their function in a complex manner. We propose that the fact that in some situations the soil and in others the plant type is the key factor determining soil microbial diversity is related to the complexity of the microbial interactions in soil, including interactions between microorganisms and soil and microorganisms and plants. A conceptual framework, based on the relative strengths of the shaping forces exerted by plant and soil versus the ecological behavior of microorganisms, is proposed.
-
-
-
MICROBIAL DYNAMICS AND INTERACTIONS IN THE SPERMOSPHERE
Vol. 42 (2004), pp. 271–309More Less▪ AbstractThe spermosphere represents a short-lived, rapidly changing, and microbiologically dynamic zone of soil surrounding a germinating seed. It is analogous to the rhizosphere, being established largely by the carbon compounds released into the soil once the seed begins to hydrate. These seed exudations drive the microbial activities that take place in the spermosphere, many of which can have long-lasting impacts on plant growth and development as well as on plant health. In this review, I discuss the nature of the spermosphere habitat and the factors that give rise to its character, with emphasis on the types of microbial activities in the spermosphere that have important implications for disease development and biological disease control. This review, which represents the first comprehensive synthesis of the literature on spermosphere biology, is meant to illustrate the unique nature of the spermosphere and how studies of interactions in this habitat may serve as useful experimental models for testing hypotheses about plant-microbe associations and microbial ecology.
-
-
-
BIOLOGICAL CONTROL OF CHESTNUT BLIGHT WITH HYPOVIRULENCE: A Critical Analysis
Vol. 42 (2004), pp. 311–338More Less▪ AbstractMost hypovirulence in the chestnut blight fungus, Cryphonectria parasitica, is associated with infection by fungal viruses in the family Hypoviridae. Hypovirulence has controlled chestnut blight well in some locations in Europe and in Michigan in the United States. In contrast, with few exceptions, biological control has failed almost completely in eastern North America. Therapeutic treatment of individual cankers is successful in most cases, but the success of hypovirulence at the population level depends on the natural spread of viruses. Characteristics of three interacting trophic levels (virus, fungus, and tree), plus the environment, determine the success or failure of hypovirulence. Vegetative incompatibility restricts virus transmission, but this factor alone is a poor predictor of biological control. Any factor reducing the rate of chestnut blight epidemics enhances hypovirus invasion. Overall, however, not enough is understood about the epidemiological dynamics of this system to determine the crucial factors regulating the establishment of hypovirulence in chestnut forests.
-
-
-
INTEGRATED APPROACHES FOR DETECTION OF PLANT PATHOGENIC BACTERIA AND DIAGNOSIS OF BACTERIAL DISEASES
Vol. 42 (2004), pp. 339–366More Less▪ AbstractDisease diagnosis is based on a number of factors, including laboratory tests for pathogen identification. Rapid development of genomic techniques for characterization of bacteria over the past decade has greatly simplified and improved pathogen detection and identification, but DNA-based methods have not yet entirely replaced traditional culture and phenotypic tests in the plant industry. The first section of this review focuses on rapid immunodiagnostic and DNA-based detection methods for known bacterial pathogens in plants or plant products, which often manifest no symptoms of disease. The second section covers the broader topic of disease diagnosis and new methods for identifying and characterizing bacteria.
-
-
-
NEMATODE MOLECULAR DIAGNOSTICS: From Bands to Barcodes
Vol. 42 (2004), pp. 367–383More Less▪ AbstractNematodes are considered among the most difficult animals to identify. DNA-based diagnostic methods have already gained acceptance in applications ranging from quarantine determinations to assessments of biodiversity. Researchers are currently in an information-gathering mode, with intensive efforts applied to accumulating nucleotide sequence of 18S and 28S ribosomal genes, internally transcribed spacer regions, and mitochondrial genes. Important linkages with collateral data such as digitized images, video clips and specimen voucher web pages are being established on GenBank and NemATOL, the nematode-specific Tree of Life database. The growing DNA taxonomy of nematodes has lead to their use in testing specific short sequences of DNA as a “barcode” for the identification of all nematode species.
-
-
-
TYPE III SECRETION SYSTEM EFFECTOR PROTEINS: Double Agents in Bacterial Disease and Plant Defense
Vol. 42 (2004), pp. 385–414More Less▪ AbstractMany phytopathogenic bacteria inject virulence effector proteins into plant cells via a Hrp type III secretion system (TTSS). Without the TTSS, these pathogens cannot defeat basal defenses, grow in plants, produce disease lesions in hosts, or elicit the hypersensitive response (HR) in nonhosts. Pathogen genome projects employing bioinformatic methods to identify TTSS Hrp regulon promoters and TTSS pathway targeting signals suggest that phytopathogenic Pseudomonas, Xanthomonas, and Ralstonia spp. harbor large arsenals of effectors. The Hrp TTSS employs customized cytoplasmic chaperones, conserved export components in the bacterial envelope (also used by the TTSS of animal pathogens), and a more specialized set of TTSS-secreted proteins to deliver effectors across the plant cell wall and plasma membrane. Many effectors can act as molecular double agents that betray the pathogen to plant defenses in some interactions and suppress host defenses in others. Investigations of the functions of effectors within plant cells have demonstrated the plasma membrane and nucleus as subcellular sites for several effectors, revealed some effectors to possess cysteine protease or protein tyrosine phosphatase activity, and provided new clues to the coevolution of bacterium-plant interactions.
-
-
-
PLANT VIRUS SATELLITE AND DEFECTIVE INTERFERING RNAS: New Paradigms for a New Century
Vol. 42 (2004), pp. 415–437More Less▪ AbstractAlthough many subviral RNAs reduce or intensify disease symptoms caused by the helper virus, only recently have clues concerning the mechanism of disease modulation been revealed. New models for DI RNA-mediated reduction in helper virus levels and symptom attenuation include DI RNA enhancement of posttranscriptional gene silencing (PTGS), which is an antiviral defense mechanism in plants. Symptom enhancement by the satRNA of Cucumber mosaic virus is caused by minus-strand induction of the programmed cell death pathway. In contrast, symptom enhancement by satC of Turnip crinkle virus is due to satC interference with virion formation, leading to increased levels of free coat protein, which is the viral suppressor of PTGS. Mutualism between satRNA and helper virus can be seen for the satRNA of Groundnut rosette virus, which contributes to the virus by allowing virion assembly. These novel findings are leading to re-evaluation of the relationships between subviral RNAs, helper viruses, and hosts.
-
-
-
CHEMICAL BIOLOGY OF MULTI-HOST/PATHOGEN INTERACTIONS: Chemical Perception and Metabolic Complementation
Vol. 42 (2004), pp. 439–464More Less▪ AbstractThe xenognostic mechanisms of two multi-host pathogens, the causative agent of crown gall tumors Agrobacterium tumefaciens and the parasitic plant Striga asiatica, are compared. Both organisms are general plant pathogens and require similar information prior to host commitment. Two mechanistic strategies, chemical perception and metabolic complementation, are used to ensure successful host commitment. The critical reactions at host-parasite contact are proton and electron transfer events. Such strategies may be common among multi-host pathogens.
-
Previous Volumes
-
Volume 62 (2024)
-
Volume 61 (2023)
-
Volume 60 (2022)
-
Volume 59 (2021)
-
Volume 58 (2020)
-
Volume 57 (2019)
-
Volume 56 (2018)
-
Volume 55 (2017)
-
Volume 54 (2016)
-
Volume 53 (2015)
-
Volume 52 (2014)
-
Volume 51 (2013)
-
Volume 50 (2012)
-
Volume 49 (2011)
-
Volume 48 (2010)
-
Volume 47 (2009)
-
Volume 46 (2008)
-
Volume 45 (2007)
-
Volume 44 (2006)
-
Volume 43 (2005)
-
Volume 42 (2004)
-
Volume 41 (2003)
-
Volume 40 (2002)
-
Volume 39 (2001)
-
Volume 38 (2000)
-
Volume 37 (1999)
-
Volume 36 (1998)
-
Volume 35 (1997)
-
Volume 34 (1996)
-
Volume 33 (1995)
-
Volume 32 (1994)
-
Volume 31 (1993)
-
Volume 30 (1992)
-
Volume 29 (1991)
-
Volume 28 (1990)
-
Volume 27 (1989)
-
Volume 26 (1988)
-
Volume 25 (1987)
-
Volume 24 (1986)
-
Volume 23 (1985)
-
Volume 22 (1984)
-
Volume 21 (1983)
-
Volume 20 (1982)
-
Volume 19 (1981)
-
Volume 18 (1980)
-
Volume 17 (1979)
-
Volume 16 (1978)
-
Volume 15 (1977)
-
Volume 14 (1976)
-
Volume 13 (1975)
-
Volume 12 (1974)
-
Volume 11 (1973)
-
Volume 10 (1972)
-
Volume 9 (1971)
-
Volume 8 (1970)
-
Volume 7 (1969)
-
Volume 6 (1968)
-
Volume 5 (1967)
-
Volume 4 (1966)
-
Volume 3 (1965)
-
Volume 2 (1964)
-
Volume 1 (1963)
-
Volume 0 (1932)