Download Glossary of Bacterial Diseases of Plants aggressiveness relative

Glossary of Bacterial Diseases of Plants
aggressiveness
relative ability of a plant pathogen to colonize and cause damage to plants (see also
virulence)
antibiosis
an association between organisms, or between an organism and a metabolic product
of another organism, that is harmful to one of them
antibiotic
a chemical compound produced by one microorganism that inhibits growth or kills
other living organisms
avirulence (avr) gene
gene in a pathogen that usually causes a hypersensitive reaction, is associated with
active plant defense reactions in a resistant plant, and causes disease in a susceptible
plant
avirulent (syn. nonpathogenic)
unable to cause disease (see virulent)
bacterial streaming
large populations of bacteria that exude from the cut surface of infected plant tissue
when observed with a microscope
bactericide
a chemical or physical agent that kills bacteria
bacteriocin
a protein antibiotic, one or more types of which can be produced and excreted by
certain strains of bacteria
bacteriophage
a virus that infects a bacterium
bacterium (pl. bacteria)
a prokaryotic, microscopic, single-celled organism with a cell wall that increases by
binary fission
biological control (syn. biocontrol)
exploitation by humans of the natural competition, parasitism and/or antagonism of
organisms for management of pests and pathogens
biotype
a subdivision of a species, subspecies, or race based on some identifiable
physiological trait such as a specific virulence pattern
blight
sudden, severe, and extensive spotting, discoloration, wilting, or destruction of leaves,
flowers, stems, or entire plants
canker
a plant disease characterized (in woody plants) by the death of cambium tissue and
loss and/or malformation of bark, or (in non-woody plants) by the formation of
sharply delineated, dry, necrotic, localized lesions on the stem; "canker" may also be
used to refer to the lesion itself, particularly in woody plants
CFU (abbr. for colony forming unit)
the number of colonies formed per unit of volume or weight of a cell or spore
suspension
colonization
establishment and ramification of a pathogen within a host plant
colony
growth of a microorganism in mass, especially as a pure culture
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cytopathology
the study of changes induced by disease at the cellular level
disease
abnormal functioning of an organism
disease cycle
succession of all of events and interactions among the host, parasite and environment
that occur in a disease, from initial infection of the plant by a causal agent, through
pathogenesis, to over-seasoning, until another infection occurs
disease triangle
a memory aid that diagrams the three important components necessary for disease:
susceptible plant, virulent pathogen and favorable environment
gall (syn. tumor)
abnormal swelling or localized outgrowth, often roughly spherical, produced by a
plant as a result of attack by a fungus, bacterium, nematode, insect, or other organism
hyperplasia (adj. hyperplastic)
abnormal increase in the number of cells, often resulting in the formation of galls or
tumors
hypersensitive response (HR)
rapid and localized cell death at the site of infection in resistant interactions between
plants and pathogens
hypertrophy (adj. hypertrophic)
abnormal increase in the size of cells in a tissue or organ, often resulting in the
formation of galls or tumors
in vitro
in glass, on artificial media, or in an artificial environment; outside the host
in vivo
within a living organism
incubation period
the time between penetration of a host by a pathogen and the first appearance of
disease symptoms; the time during which microorganisms inoculated onto a medium
are allowed to grow
infect (n. infection)
to enter, invade, or penetrate and establish a parasitic relationship with a host plant
inoculum (pl. inocula)
pathogen or its parts, capable of causing infection when transferred to a favorable
location
inoculum density
a measure of the number of propagules of a pathogenic organism per unit area or
volume
intercellular
between or among cells
intracellular
through or within cells
isolate
(n.) a culture or subpopulation of a microorganism separated from its parent
population and maintained in some sort of controlled circumstance;
(v.) to remove from soil or host material and grow in pure culture
leaf spot
a plant disease lesion typically restricted in development in the leaf after reaching a
characteristic size
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microorganism
an organism of such small size that it can only be seen as an individual organism with
the aid of a microscope (see also microbe)
MLO (acronym for mycoplasmalike organism)
archaic term for phytoplasma; plant-parasitic pleomorphic mollicute (prokaryote with
no cell wall) found in phloem tissue; cannot yet be grown on artificial nutrient media
(contrasts with phytoplasma)
mollicute
one of a group of prokaryotic organisms bounded by flexuous membranes and lacking
cell walls (see also phytoplasma, spiroplasma)
necrosis (adj. necrotic)
death of cells or tissue, usually accompanied by darkening to black or brown
ooze
mass of bacteria
pathogen (adj. pathogenic)
a disease-producing organism or agent
pathogenesis
production and development of disease
pathogenicity
ability to cause disease
pathology
the study of diseases
pathotype
a subdivision of a pathogen species characterized by its pattern of virulence or
avirulence to a series of differential host varieties
pathovar (abbrev. pv.)
a subdivision of a plant-pathogenic bacterial species defined by host range; pathovar
for bacteria is equivalent to forma specialis for fungi
phytoplasma
plant-parasitic pleomorphic mollicute (prokaryote with no cell wall) found in phloem
tissue; cannot yet be grown on artificial nutrient media (contrasts with
mycoplasmalike organism, acronym MLO)
plant pathology
the study of plant diseases (see also phytopathology)
plasmid
a circular, self-replicating hereditary element that is not part of a chromosome;
plasmids are used in recombinant DNA experiments as acceptors and vectors of
foreign DNA
primary inoculum
inoculum, usually from an overwintering source, that initiates disease in the field, as
opposed to inoculum that spreads disease during the season (see also initial inoculum)
(contrasts with secondary inoculum)
protection
various methods of plant disease management, including cultural practices that create
barriers or reduce the chance of infection, chemical protection, methods of biological
control that protect plants, and genetic resistance.
resistant (n. resistance)
possessing properties that prevent or impede disease development (contrasts with
susceptible)
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rot
softening, discoloration, and often disintegration of plant tissue as a result of fungal or
bacterial infection
scab
roughened, crustlike diseased area on the surface of a plant organ
secondary infection
infection resulting from the spread of infectious material produced after a primary
infection or from secondary infections without an intervening inactive period
secondary inoculum
inoculum produced by infections that took place during the same growing season
(contrasts with initial inoculum, primary inoculum)
sp. (pl. spp.)
abbreviation for species; a genus name followed by sp. means that the particular
species is undetermined; spp. after a genus name means that several species are being
referred to
spot
a symptom of disease characterized by a limited necrotic area, as on leaves, flowers,
and stems
strain
a distinct form of an organism or virus within a species, differing from other forms of
the species biologically, physically, or chemically
susceptible (n. susceptibility)
prone to develop disease when infected by a particular pathogen (contrasts with
resistant)
symptom
indication of disease by reaction of the host, e.g., canker, leaf spot, wilt (contrasts
with sign)
tolerance (adj. tolerant)
ability of a plant to endure an infectious or noninfectious disease, adverse conditions,
or chemical injury without serious damage or yield loss; (of pesticides) the amount of
chemical reside legally permitted on an agricultural product entering commercial
channels, usually measured in parts per million (ppm)
toxin
poisonous substance of biological origin
tumor
abnormal swelling or localized outgrowth, often roughly spherical, produced by a
plant as a result of attack by a fungus, bacterium, nematode, insect, or other organism
(see also gall)
vascular wilt disease
a xylem disease that disrupts normal uptake of water and minerals, resulting in wilting
and yellowing of foliage
virulent
highly pathogenic; having the capacity to cause severe disease (contrasts with
avirulent)
walling-off
separation of diseased from healthy tissues by barrier tissues produced by a diseased
plant
American Phytopathological Society (APS)
Illustrated Glossary of Plant Pathology
Authors: C.J. D'Arcy, D.M. Eastburn, and G. L. Schumann
(with acknowledgement of contributions from M.C. Shurtleff, P.A. Arneson, F.H. Tainter, and T.A. Evans)
http://www.apsnet.org/edcenter/illglossary/Pages/default.aspx
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