A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Search | Sources | Home |

On-Line Glossary: E

Each entry consists of a term (in bold), a definition of the term, and a number in parentheses (0) indicating the source of the definition. Clicking on the speaker icon will give you the pronunciation of the term. (Be sure to close the window for the sound player after each use.) The pencil icon will give you a drawing, and the camera icon will give you a photograph.


echinate. Having sharply pointed spines. (7)

echinulate. Covered with small spines. (16)

ectoparasite. A parasite that remains external to the host's cells or tissues. (16)

ectosymbiosis. Symbiosis in which one member (microsymbiote) develops on the outside of the other member. (20)

ectotrophic. Refers to a mycorrhiza in which the mycelium forms an external covering on the root. (20)

edema. See oedema.

eelworm. Nematode. (20)

effective dissemination. Synonymous with inoculation. (20)

effuse. Spreading out loosely or flat. (21)

electrophoresis. A procedure by means of which the members of a heterogenous population of charged particles can be separated by virtue of their dissimilar migration characteristics in an electric field. (16)

electroporation. A method by which nucleic acids or virus particles can be introduced into protoplasts or cells by creating transient pores in the plasma membrane using an electric pulse. (10)

elicitor. A molecule produced by the host (or pathogen) that induces a response by the pathogen (or host). (2)

ELISA. Enzyme-linked immunosorbent assay. A highly sensitive immunoassay for specific antibodies or antigens. (16)

ellipsoid. Having every plane section an ellipse or a circle. (17)

ellipsoidal. See ellipsoid.

emarginate. Of gills, notched near the stipe. (17)

enation. A symptom caused by certain plant viruses in which there are small outgrowths on the plant. (10)

encysted. Surrounded by a hard shell (cyst). (20)

endemic. Of a disease: Native to a particular place. (3)

endoconidiophore. A conidiophore that produces conidia within itself. (21)

endoconidium. A conidium produced endogenously in a hypha or conidiophore. (Pl. endoconidia.) (17)

endogenous. Arising from within the generating structure. (20)

endonuclease. A nuclease which cleaves phosphodiester bonds within a nucleic acid strand. (16)

endoparasite. A parasite that lives intracellularly or within the tissues of the host. (16)

endosymbiosis. Symbiosis in which one member (microsymbiote) lives within the other. (20)

endotrophic. Refers to a mycorrhiza in which the mycelium grows within the cortical cells of the root (e.g., in orchids). (20)

enzyme. A protein produced by living cells that can catalyze a specific organic reaction. (2)

epidemic. A change in the amount of disease in a population in time and space. . (3)

epidemiology. 1. The study of the interrelationships between a given pathogen, the environment, and groups or populations of the relevant hosts. (16) 2. The study of epidemics. (20)

epidermis. The superficial layer of cells occurring on all plant parts. (2)

epinasty. Downward curling of a leaf blade resulting from more rapid cell growth on the upper side of a petiole than on the lower side; often a hyperplastic symptom of plant disease. (20)

epiparasite. An organism parasitic on another that parasitizes a third. (21)

epiphyte. An epiphytic organism.

epiphytic. Growing externally on a plant without parasitizing it. (3)

epiphytotic. See epidemic. (3)

epiptygma. In nematodes: A vulval flap. (14)

epitype. A specimen selected as a standard for a species or lower taxon when all original material except for illustrations has been destroyed. (22)

eradicant. Any chemical agent that eliminates particular pathogen(s) from diseased plants treated with that agent. (16)

eradication. Control of plant disease by eliminating the pathogen after it is established or by eliminating the plants that carry the pathogen. (2)

ergot. Disease of certain grasses and cereals, especially rye, caused by Claviceps purpurea; also the spur-shaped sclerotium of C. purpurea that replaces the grain in a diseased inflorescence. (20)

erumpent. Breaking through the surface; bursting forth. (21)

escape. Failure of inherently susceptible plants to become diseased, even though disease is prevalent. (20)

esophagus. In nematodes: The portion of the alimentary canal between the buccal capsule, or stoma, and the anterior portion of the intestine. (14)

ethidium bromide. (2,7-diamino-10-ethyl-9-phenylphenanthridinium bromide). A trypanocidal, bacteriostatic dye that binds to DNA and fluoresces under near-ultraviolet light; used for tracking nucleic acids. (16)

etiolation. A phenomenon exhibited by plants grown in the dark: etiolated plants are pale yellow and have long internodes and small leaves. (20)

etiology. The study of cause; that phase of plant pathology dealing with the causal agent and its relations with the susceptible plant. (20)

exclusion. The principle of plant disease prevention in which the pathogen is prevented from entering a given region. (20)

excretory. In nematodes: A tube or canal, lined with cuticle, that leads to the excretory pore. (14)

excretory pore. In nematodes: The exterior opening of the excretory system, generally located on the ventral side of the body near the basal region of the esophagus; also known as the orifice of the cervical gland. (14)

exogenous. Arising on the outside of the generating structure. (20)

exonuclease. A nuclease that sequentially removes nucleotides from one end of a strand of nucleic acid. (16)

exopathogen. Nonparasitic organism whose extracellular toxic metabolites cause disease in plants. (20)

extracellular. Outside the cells. (20)

exudate. Material that has passed from within a plant structure to the outer surface or into the surrounding medium; as in leaf exudate, root exudate, etc. (8)

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Search | Sources | Home |