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On-Line Glossary: T

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.


tail. In nematodes: The portion of the body between the anus and the posterior terminus. (14)

taxon. A taxonomic group of any rank. (22)

telamon. In nematodes: Rigid, sclerotized portion of the cloacal wall that apparently guides the spicules from the spicular pouch into the cloaca. (14)

teleutosorus. An old term for telium. (17)

teleutospore. See teliospore. (16)

teliospore. A usually thick-walled, usually resting spore, which is the site of karyogamy and produces the basidium (in the Uredinales and Ustilaginales). (15)

telium. The final sorus (stage III) produced in the life cycle of the Uredinales and producing teliospores. (Pl. telia.) (15)

teleomorph. The stage characterized by the production of asci/ascospores, basidia/basidiospores, teliospores, or other basidium-bearing organs. (15)

tessellate. In nematodes: Checkered; a type of cuticular pattern in which the longitudinal ridges are broken by transverse striations into rows of squares. (14)

testis. A male reproductive organ in which spermatozoa are produced. (18)

texture. The arrangement of the components of the different tissues, as compact, loose, etc. (17)

thallic. One of two basic kinds of conidiogenesis; the conidial initial enlarges after it has been delimited by one or more septa. The conidium is differentiated from a whole cell. (See blastic.) (7)

thallospore. A conidium that has no conidiophore or is not separate from the hypha or conidiophore that produced it. (21)

thallus. Any simple vegetative plant body that lacks roots, stems and leaves. (Pl. thalli.) (15)

therapy. Principle of plant disease control marked by the cure of disease, as with heat or systemic chemicals. (20)

threadworm. Nematode. (20)

tissue. A group of cells of similar structure which performs a special function. (2)

titillae. In nematodes: Small projections on either side of the distal end of the gubernaculum. (14)

toadstool. Mushroom. (20)

tobamovirus. (Siglum of tobacco mosaic virus). Member of a group of plant viruses with rigid, rod-shaped particles containing one molecule of linear RNA, easily sap-transmitted and transmitted in nature by contact and (in the case of some viruses in this group) in seed. (5)

tolerance. 1. The ability of a plant to sustain the effects of a disease without dying or suffering serious injury or crop loss. 2. The amount of toxic residue allowable in or on edible plant parts under the law. (2)

tombusvirus. (Siglum of tomato bushy stunt virus). Member of a group of plant viruses with isometric (icosahedral) particles containing one molecule of linear RNA, readily sap-transmitted and also transmitted through soil. (5)

tospovirus. (Siglum of tomato spotted wilt virus). Member of a small group of plant viruses with spherical particles containing three RNA species, transmitted in nature by thrips in a persistent manner. (5)

topotype. A specimen collected at the type locality. (14)

toxicity. The capacity of a compound to produce injury or death. (2)

toxin. A compound produced by a microorganism and being toxic to a plant or animal. (2)

trama. The sterile tissue of a basidiocarp. (15)

transduction. The virus-mediated transfer of host DNA (chromosomal or plasmid) from one host cell (the donor) to another (the recipient). Transduction was first observed in bacteriophage/bacterium systems, but has since also been found to be mediated by certain viruses infecting eukaryotic cells. (16)

transfection. The successful virus-infection of cells following their inoculation with viral nucleic acid. (10)

transformant. A cell or organism that has undergone genetic transformation. (16)

transformation. A process in which exogenous DNA is taken up by a (recipient) cell or protoplast, in which it may be incorporated into the chromosome (or, e.g., into a plasmid) by homologous recombination or converted into an autonomous replicon. The DNA (transforming or donor DNA) may be a fragment of chromosomal DNA from a related strain, a plasmid, or a viral genome. (16)

translocation. Transfer of nutrients or virus through the plant. (2)

transmission. The transfer of a pathogen from one plant to another, or from one plant organ to another. (2)

transpiration. The loss of water vapor from the surface of leaves and other aboveground parts of plants. (2)

transposon. A discrete piece of DNA that can insert itself into other DNA sequences within the cell. The ends of the transposon DNA are usually inverted repeats. (10)

tretic. Of conidiogenesis: The sort of blastic conidiogenesis in which each conidium is delimited by an extension of the inner wall of the conidiogenous cell. Tretoconidia are solitary or in acropetal chains. (7)

trichogyne. In some algae, lichens, and fungi, a projection from the female sex organ that receives the male gamete or nuclei before fertilization (karyogamy). (20)

trifurcate. Bearing three branches or forks. (14)

triradiate. Having three radiating arms or branches. (14)

truncate. Having the end squared off or even. (14)

tumefaction. A plant tumor or gall. (20)

tumor. An uncontrolled growth of tissue or tissues. (2)

tylosis. A balloon-like outgrowth from a xylem parenchyma cell that expands into and blocks the lumen of a xylem vessel or a tracheid. (Pl. tyloses.) (16)

tymovirus. (Siglum of turnip yellow mosaic virus). Member of a group of plant viruses with isometric (icosahedral) particles containing a single molecule of linear RNA, easily transmitted mechanically and transmitted in nature by beetles. (5)

type. An object that serves as the basis for the name of a taxon. (22)

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