agr agriculture anat anatomy bio biology biot biotechnology bot botany bp base pair(s)

cf confer, compare chem chemistry cyto cytology eco ecology env environment eth ethology evol evolution fore forestry gene genetics hort horticulture

Lat Latin meth methods, methodology micr microscopy phy physics phys physiology phyt phytopathology pl plural prep preparation, techniques seed seed science, seed production sero serology stat statistics, experimental planning syn synonymous tax taxonomy tech technology

US term used in the United States zoo zoology


A chromosome: anyiof the standard chromosomes of a given genome cyto

A line: the seed-bearing parent line used to produce hybrid seed that is male sterile; in wheat hybrid seed production, a male-sterile parent line used to produce hybrid seeds and, hence, the seed-producing parental line seed >>> Figure 2

ABA >>> abscisic acid abaxial: the surface of a leaf facing away from the axis or stem of a plant, as opposed to adaxial bot aberrant: having uncommon characteristics or not strictly true to the pheno-type gene aberration: variation of chromosome structure caused by induced or spontaneous mutations; in general, a nontypical form or function cyto; in microscopy, failure of an optical or electron-optical lens to produce exact geometric (and chromatic) correspondence between an object and its image micr aberration rate: the portion of chromosomal changes as compared to normal chromosomes cyto abiotic: factors or processes of the nonliving environment (climate, geology, atmosphere)

abjection: the separating of a spore from a sporophore or sterigmaby a fungus bot abjunction: the cutting off of a spore from a hypha by a septum bot ablastous: without germ or bud bot abnormal: unusual variance from the natural habit abort: to fail in the early stages of formation; the collapse or disappearance of seeds or cells bot abortive: defective or barren bot

abortive infection: when pathogenic microorganisms fail to become established in the tissue of the host phyt aboveground biomass >>> biomass abscise: separate by abscission, as a leaf from a stem bot abscisic acid (ABA): a growth regulator or plant hormone such as auxins, gib-berellins, or cytokinins; it occurs in various tissues and seeds; the substance is thought to play an important role in the regulation of certain aspects of seed growth and development, as well as being involved in fruit growth, rejection of plant organs such as leaves and fruits, and certain other physiological phenomena phys abscisin(e) >>> abscisic acid abscissa: in monovariable distributions the abscissa (x-axis) is used for plotting the trait, while the ordinate (y-axis) gives the frequencies stat abscission: rejection of plant organs (e.g., of leaves in autumn) bot phys >>> abscisic acid absorbency: a measure of the loss of intensity of radiation passing through an absorbing medium meth absorption: uptake of substances, usually nutrients, water, or light, by plant cells or tissue; in soil science, the physical uptake of water or ions by a (soil) substance phys; in microscopy, the interaction of light with matter, resulting in decreased intensity across entire spectrum or loss of intensity from a portion of the spectrum micr absorption spectrum: a graph that shows the percentage of each wavelength of light absorbed by a pigment (e.g., chlorophyll) phys absorptive: the state or process of being absorbed abundance: the estimated number of individuals of a species in an area or population phyt acantha: a spine, thorn, or prickle bot acanthocarpous: a fruit showing prickles bot acaricide: a pesticide used to kill or control mites or ticks phyt acarides: (pl) related to the spider animals; more than 10,000 species are known; many species parasitically live on plants zoo phyt acarpous: describes a plant that is sterile bot >>> sterile acaudate: not having a tail phyt acauline: not having a culm bot accelerated aging test >>> aging test acceleration: the time rate of change of velocity with respect to magnitude or direction phy acceptor: an atom that receives a pair of electrons to form a chemical bond chem phys accession: a distinct sample of germplasm (cultivar, breeding line, population) that is maintained in a gene bank for conservation and evaluation; in order to represent the genetic variation of a sample, ideally 4,000 seeds are needed for genetically homogeneous lines and about 12,000 seeds for heterogeneous accession number: a unique identifier assigned to each accession when it is registered within a gene bank accessory bud: buds that are at or near the nodes but not in the axils of leaves bot accessory chromosome: a chromosome that is present in addition to the normal chromosome complement cyto >>> B chromosome accessory DNA: surplus DNA present in certain cells or cell stages due to gene amplification gene accidental host: that type of host on which the pathogen or parasite lives only for a limited time; it has no particular importance for the reproduction of the pathogen or parasite phyt >>> host accidental sample: a sampling technique that makes no attempt to achieve representativeness, but chooses subjects based on convenience and accessibility stat acclimation >>> acclimatization acclimatization: changes involving the synthesis of proteins, membranes, and metabolites that occur in a plant in response to chilling or freezing temperatures that protect tissues or confer tolerance to the cold phys acclimatized: a state of physiological adjustment by plants to changed environmental or stress conditions phys accommodation: the act of adjusting the eye to bring objects that are closer to the eye into focus micr accumbent: used to describe the first sprouts of an embryo when they lie against the body of the seed bot accumulation center: an area where a great deal of variation of a given species or crop plant may be found, but which is not considered a center of origin acellular: describing tissue or organisms that are not made up of separate cells but often have more than one nucleus bot acentric: chromosome, chromosome segments, or chromatids that show no centromere; applied to a chromosome fragment formed during cell division that lacks a centromere; this fragment is unable to follow the rest of the chromosomes in migration toward one or the other pole, as it has lost its point of attachment to the cell spindle cyto >>> Figure 11

acephalous: not having a head phyt acephate: a systemic insecticide that is used to control pests (e.g., aphids, scale, and thrips) phyt acerose: needlelike and stiff, like pine needles bot acervate: growth in heaps or groups bot acetabuliform: saucerlike in form bot acetaldehyde: a simple aldehyde that is a bridge product of alcoholic fermentation chem acetate: a salt or ester of acetic acid chem acetic acid (ethanoic acid): a carboxylic acid, CH3COOH, and simple fatty acid; a final product of several fermentation, oxidation, or rot processes; plays a crucial role in energy metabolism chem aceto-carmine staining: used as a dye for staining of chromosomes; usually cells or tissues are prepreated (fixation) for 12-24 hours with a mixture of alcohol and acetic acid (3:1) or alcohol, acetic acid, and chloroform after CARNOY; prior to squashing the material it is stained with aceto-carmine cyto micr >>> opuntia >>> CARNO's fixative acetone: a simple but most important ketone that is often used as a lipid solvent chem aceto-orcein: a fluid consisting of the dye orcein dissolved in acetic acid that is used in chromosome staining cyto micr acetylation: introduction of an acetyl group into a compound chem phys achene: a small, usually single-seeded, dry, indehiscent fruit formed from a single carpel (e.g., the feathery achene of Clematis); variants of the achene include caryopsis, cypsela, nut, and samara bot achiasmate: meiosis and/or chromosome pairing without crossing over and chiasma formation cyto >>> Figure 15

achlorophyllous: a plant or leaf without chlorophyll bot achromat: a microscope objective corrected for axial chromatic aberration micr achromatic: parts of the nucleus not stainable by common chromosome dyes cyto achromatic aplanatic condenser: a well-adapted microscope condenser lens that is corrected for chromatic and spherical aberrations micr achromatic lens (achromat): a lens cluster whose foci and power are made the same for two wavelengths; the simplest achromat is a doublet that combines two single lenses with different dispersions and curvatures to achromatize the combination micr achromatin: that part of the nucleus that does not stain with basic dye cyto achromycin: the trade name for tetracycline; an antibacterial antibiotic from Streptomyces spp. biot acicular: pointed or needle shaped bot acicular leaf: a pointed or needle-shaped leaf (e.g., in conifers) bot acid phosphatase (Acph): an enzyme that is a member of hydrolases; because of its variability it is sometimes used as a biochemical marker in genetic studies chem gene acid soil: specifically a soil with pH value < 7.0, which is caused by the presence of active hydrogen and/or aluminum ions; the pH value decreases as the activity of these ions increases agr acid(ic) dye: an organic anion that stains positively charged macromolecules and acts on protoplasm micr acidity: in soil science, a measure of the activity of the hydrogen and aluminum ions in wet soil, usually expressed as pH value; crop plants show specific requirements; some of them grow reasonably well on acid soils (e.g., cow-pea—pH 5.0-7.0; oats, rye—pH 5.5-7.5; maize, sorghum, wheat—pH 6.0-7.5; barley—pH 6.5.-7.5; alfalfa—pH 7.0-8.0) agr acidophilic: in cytology, having an affinity for acid stains (eosinophilic) cyto; in ecology, thriving in or requiring an acid environment eco acidophilous >>> acidophilic acinaceous: consisting of or full of kernels bot acinaciform: shaped like a scimitar (e.g., the shape of the pods of some beans) bot aconitase (Aco): an enzyme (dehydratase) that catalyzes the production of iso-citric acid from citric acid; because of its variability it is sometimes used as a biochemical marker in genetic studies chem gene acorn: the nonsplitting, one-seeded fruit of, for example, an oak tree bot acquired character: a nonheritable modification of structures or functions impressed on an individual by environmental influences during its development gene >>> modification acquired immunity: an immunity that may be induced by means of preimmu-nization phyt acquired resistance: plant resistance to a disease activated after inoculation of the plant with certain microorganisms or treatment with certain chemical compounds phyt acre: 1 acre = 0.4047 ha = 4,840 square yards =10 square chains; 640 acres = 1 square mile (also called a section)

acreable: in terms of an acre or per acre agr acreage: extent or area in acres agr acridine: a chemical that is capable of causing frameshift mutations in the DNA sequence; several derivatives of acridine, such as acridine orange, are used as dyes or biological stains chem gene cyto >>> fluorescence staining >>> mutagen acridine orange: an acridine dye that functions as both a fluorochrome and a mutagen micr cyto gene >>> fluorescence staining >>> mutagen acrocarpic: fruits and/or seeds are formed on the top of a stem of a plant bot acrocarpous >>> acrocarpic acrocentric: the centromere is present on the end or close to the end of a chromosome cyto >>> Figure 11

acropetal: toward the apex; the opposite of basipetal bot acrosyndesis: incomplete end-to-end chromosome pairing cyto actinomycin: an antibiotic produced by Streptomyces chrysomallus that prevents the transcription of mRNA micr cyto >>> tetracycline activator: in enzymology, a proteinlike substance that is able to stimulate developmental processes phys; in molecular biology, a protein upstream from a gene on which the DNA binds; it activates the transcription of the gene gene active collection: a collection of germplasm used for regeneration, multiplication, distribution, characterization, and evaluation; ideally germplasm should be maintained in sufficient quantity to be available on request; it is commonly duplicated in a base collection and is often stored under medium- to long-term storage conditions meth active immunity: all means and reactions that enable a plant to prevent an interaction with a pathogen phyt active ingredient: in any pesticide product, the component that kills or controls target pests phyt >>> active substance active site: that portion of an enzyme where the substrate molecules combine and are transformed into their reaction products phys active substance: pesticides, herbicides, etc., are usually mixtures of different substances; among them the active substance is the most important one as it attacks the pathogen phyt >>> active ingredient active transport: the passage of substances across a cell membrane against a concentration gradient that requires energy phys activity rhythm: an individual's daily pattern of physiological activity phys acyclic: not cyclic; in botany, an acyclic flower bot; in chemistry, of or pertaining to a chemical compound not containing a closed chain or ring of atoms chem adaptability: the potentiality for adaptation; the ability of an individual or taxon to cope with environmental stress; the range and extent of reaction is genetically determined phys adaptable: capable of being adapted or able to adjust oneself readily to different environmental conditions phys >>> adaptability adaptation: the process of changes of an individual's structure, morphology, and function that makes it better suited to survive in a given environment phys adapted race >>> physiological race adaptedness: the state of being adapted phys adapter: synthetic double-stranded oligonucleotide; specific type of linker, usually wiground th one blunt and one sticky end; applied to attach sticky ends to a blunt-ended DNA molecule biot adaptive: changes of a plant that act to preserve its full development phys adaptive capacity: the genetically set range or flexibility of reactions of a plant and/or population enabling it to respond in different ways to differing conditions eco genet adaptive character: a functional or structural characteristic of an organism that enables or enhances the probability of survival and reproduction gene adaptive fitness >>> adaptedness adaptive reaction >>> adaptive capacity adaptive selection: the evolution of comparable forms in separate but ecologically similar areas eco gene evol adaptive trait >>> adaptive character adaptive trials: multilocational coordinated field experiments across the crop-growing regions in one or more countries that test adaptation of varieties or breeding strains under specific ecological conditions meth adaptive value: a measure of the reproductive efficiency of an organism or genotype compared with other organisms or genotypes gene >>> selective value adaptiveness >>> adaptedness adaptivity >>> adaptability adaxial: toward the axis syn ventral bot >>> abaxial addition line: a cell line or line of individuals carrying chromosomes or chromosome arms in addition to tground he normal standard chromosome set cyto additive effects (of genes): gene action in which the effects on a genetic trait are enhanced by each additional gene, either an allele at the same locus or genes at different loci gene >>> Tables 6, 20, 21

additive genes: gene interaction without dominance (if allele), or without epistasis (if nonallele); the expression of any genetic trait is enhanced to the simple sum of the individual genetic or allelic effects contributing to that character gene >>> Tables 6, 20, 21

additive variance (VA): the proportion of the genetic variance due to additive effects stat adelphogamy: sib pollination or pollination involving a stigma and pollen belonging to two different individuals that are vegetatively derived from the same mother gene adenine (A): a purine base that occurs in both DNA and RNA chem gene adenine sulfate: a growth factor used in some tissue culture media biot adenose: having glands or glandlike organs bot adenosine: the nucleoside formed when adenine is linked to ribose sugar chem gene adenosine diphosphate (ADP): high-energy phosphoric ester (nucleotide) of the nucleoside adenosine that functions as the principal energy-carrying compound in the living cell phys adenosine triphosphate (ATP): high-energy phosphoric ester (nucleotide) of the nucleoside adenosine that functions as the principal energy-carrying compound in the living cell phys >>> mitochondrion adhesion: the molecular attraction between substances causing their surfaces to remain in contact meth adjacent distribution: the orientation and distribution of adjacent chromosomes in the ring or chain configuration of translocation heterozygotes cyto >>> Figure 15

adjacent segregation: a reciprocal translocation heterozygote in which during meiosis the segregation of a translocated and a normal chromosome happens together, giving unbalanced gametes with duplications and deficiencies leading to nonviable zygotes; adjacent segregation is of two kinds depending on whether nonhomologous (adjacent-1) or homologous (adjacent-2) centromeres segregate together; adjacent-1 segregation is the usual type of adjacent segregation and adjacent-2 segregation is rare cyto adjacent-1 segregation: segregation of nonhomologous centromeres during meiosis in a reciprocal translocation heterozygote such that unbalanced gametes with duplications and deficiencies are produced, as opposed to alternate segregation and adjacent-2 segregation cyto adjacent-2 segregation: segregation of homologous centromeres during mei-osis in a reciprocal translocation heterozygote such that unbalanced gametes with duplications and deficiencies are produced, as opposed to alternate segregation and adjacent-1 segregation cyto adosculation: the fertilization of plants by pollen falling on the pistils bot adpressed: lying flat against (e.g., the rachilla against the palea in the grain of, e.g., barley and oats) bot adsorption: the physical binding of a particle of a particular substance to the surface of another by adhesion or penetration phy; attachment of phage to host bacterium (e.g., phage lamda adsorbs to a maltose binding protein) biot >>> lamda phage adsorption complex: the various substances in the soil that are capable of adsorption (e.g., clay or humus) agr adspersed: to have a wide distribution; scattered bot adult: having attained full size and strength; mature phys adult resistance: resistance not expressed at the seedling stage; it increases with plant maturity phyt adult stage >>> adult adulthood >>> adult stage aduncate: hooked, crooked, and bent bot advance crop >>> forecrop advanced character: a feature that shows a real deviation from the ancestral trait or type (e.g., an agronomic trait such as brittle rachis)

adventitious: growing from an unusual position (e. g., roots from a leaf or stem) bot >>> Figure 28

adventitious bud: a bud appearing in an unusual place (e.g., a bud on leaves) bot adventitious embryony: a condition in a seed in which the embryo arises from somatic rather than reproductive tissue; the development of a diploid embryo from nucellary or integumentary tissue (sporophyte tissue); common in certain grasses and often results in multiple embryos bot >>> twin seedling >>> Figure 28

adventitious plant: an individual that arises from somatic rather than reproductive tissue bot adventitious root: arising from any structure other than a root (e.g., from a node of a stem or from a leaf) bot adventive: a plant that has been introduced but is not yet naturalized agr aeolian soil: a type of soil that is transported from one place to another by the wind agr aerating tissue >>> aerenchyma aeration: bringing air into a substance, tissue, or soil (e.g., by earthworms or digging and turning the soil to loosen) phys agr aerator: any implement that is used for breaking up compacted soil to facilitate air and gas exchange agr aerenchyma: plant tissue containing large, intercellular air spaces bot aerial pathogens: antagonistic microorganisms that inhibit numerous fungal pathogens of aerial plant parts (e.g., Tilletiopsis spp. parasitize the cucumber powdery mildew fungus Spaerothecafuligena); present in crop soils and exert a certain degree of biological control over one or many plant pathogens phyt >>> biological control aerial pest control: pest control by utilization of aircraft and helicopters in order to be more efficient, to prevent damages of the crop, or to cope with difficult landscape and soil conditions phyt aerial root: in some epiphytic orchids, the leaves and the shoot axis are reduced or missing; then flatted and green roots take over the fixation of the plant and the function of the leaves (photosynthesis) bot aerial shoots: shoots growing high above the ground (e.g., trees, bushes, etc.) bot aerobe: an organism needing free oxygen for growth bot aerobium >>> aerobe aerosol: a colloidal substance that is suspended in the air phyt aesculin >>> glucoside afflux: the act of flowing to or toward some point or organ in a plant phys afforest: converting bare or cultivated land into forest eco afforestation: the establishment of forest by natural succession or by the planting of trees on land where they formerly did not grow eco aflatoxin: one of a group of mycotoxins produced by fungi of the genus Aspergillus phys

AFLP >>> amplified fragment length polymorphisms >>> random amplified polymorphic DNA (RAPD) technique

African cassava mosaic virus (ACMV): this disease continues to be the major constraint to both the commercial and subsistence production of cassava across central and southern Africa, causing up to 100 percent crop losses; the causative agent of the disease has been shown to be a geminivirus of the Begomovirus phyt after-ripening: a term for the collective changes that occur in a dormant seed that make it capable of germination; it is usually considered to denote physiological changes seed

AG complex: the complete set of factors assumed to be responsible for the formation of sexual organs bot agameon: a plant species reproducing exclusively by apomixis bot agamete: any nonreproducing germ cell bot agamic: reproducing asexually bot agamic complex: it refers to hybrids or their derivatives that are partially or entirely reproduced by asexual seed formation bot agamogenesis: any reproduction without the male gametes bot agamogony: a type of apomixis in which cells undergo abnormal meiosis during megasporogenesis, resulting in a diploid embryo sac rather than the normal haploid embryo sac bot >>> Figure 28

agamont: an asexual individual in whose agametangia the agametes are formed bot agamospecies: populations morphologically differentiated from one another and reproducing apomictically bot >>> Figure 28

agamospermy: a type of apomixis in which sporophytic tissue is formed, ultimately leading to seed development; it may occur through adventitious embryony or gametophytic apomixis bot >>> twin seedling >>> Figure 28

agar: a complex polysaccharide obtained from certain types of seaweed (red algae); when it is heated with water and subsequently cooled to about + 45°C, it forms a gel prep agar culture: cells, organs, tissue, or embryos artificially grown on a solid medium composed of agar together with certain nutrients, hormones, etc. biot agar gel: gels for electrophoresis that were produced from agar prep agar medium >>> agar culture agar-agar >>> agar agarose (starch) gel: an inert matrix used in electrophoresis for the separation of nucleic acids based on their size or conformation; the molecules are visualized in the gel by ultraviolet fluorescence of ethidium bromide, which is either included in the gel or in the running buffer or used to stain the gel after electro-phoresis prep agent: a natural force, object, or substance producing or used for obtaining specific results prep agglomerate: in biotechnology, a mass of cells clustered together biot; in soil science, rock composed of rounded or angular volcanic fragments agr agglutinate: fixed together as if with glue prep agglutination: the clumping of cellular components prep agglutinin: any antibody capable of causing clumping of types of cells prep agglutinogen: an antigen that causes the production of agglutinins chem biot aggregate: in soil science, a cluster of soil particles forming a pad agr aggregate fruit: a fruit development from several pistils in one flower, as in strawberry or blackberry bot >>> composite fruit aggressiveness: the ability of a pathogen to infect a plant, to break its resistance, to become a parasite on a plant, or to use a host plant for reproduction; the degree of aggressiveness can be estimated only when a pathogen meets a resistant host; when the aggressiveness copes with the resistance of the host it is termed virulence phyt aging test: a method to originally evaluate seed storability; it subjects unimbibed seeds to conditions of high temperature (+ 41°C) and relative humidity (~100 percent) for short periods (three to four days); the seeds are then removed from the stress conditions and placed under optimum germination conditions; the two environmental variables cause rapid seed deterioration; high vigor seed lots will withstand these extreme stress conditions and deteriorate at a slower rate than low vigor seeds seed agnesis: the absence of development bio phys agriculture: the science of transforming sunlight energy into plant and animal products that can be utilized in humans; the selective breeding of crop and farm animals has had an enormous impact on productivity in agriculture; modern varieties of crop plants have increased nutritional value and resistance to disease; recent developments in genetic engineering have enabled the potential use of transgenic organisms in agriculture to be explored agr

Agrobacterium rhizogenes: a species of Gram-negative, rod-shaped soil bacteria, often harboring large plasmids, called Ri plasmids. It can cause a tumorous growth known as hairy root disease in certain plants bot biot >>> Figure 27

Agrobacterium tumefaciens: a species of soil bacteria that can infect the stem of many plants and form crown gall tumors when it contains a Ti plasmid bot biot >>> Figure 27

Agrobacterium-mediated transformation: Agrobacterium is the generic name of a soil bacterium that frequently causes crown gall in many plant species; besides A. rhizogenes, A. tumefaciens is one species that is most used in DNA transfer by manipulating the Ti (tumor inducing) plasmid, which is harbored by these bacteria biot >>> Figure 27 >>> Agrobacterium rhizogenes >>> Agrobacterium tumefaciens agrobiology: the scientific study of plant life in relation to agriculture, especially with regard to plant genetics, cultivation, and crop yield agr bio agroinfection: infection of plants via soilborne pathogens phyt agronomist: the person who is doing farm management and organizes and/or realizes the production of field crops agr agronomy: the part of agriculture devoted to the production of crops and soil management; the scientific utilization of agricultural land agr air layering: a method of plant propagation in which roots are induced to form around a stem; a very narrow strip of bark is removed from around the branch or stem; a sliver of wood can be inserted into the cut to keep it open; a bundle of moist sphagnum moss is tied securely around the cut area; the moss must remain moist and the roots of the plant somewhat dry; new roots will sprout from the incision; the new plant is then cut off below the moss, potted and kept in a humid atmosphere until it is established bot air screen cleaner: the basic piece of equipment for cleaning seed, utilizing airflow and perforated screens seed airlock: an airtight chamber permitting passage to or from a space seed akaryotic: without a nucleus; a stage in the nuclear cycle before meiosis in which no or little chromatin is seen in the nucleus cyto akinete >>> akinetic akinetic: a nonmotile reproductive structure (e.g., a resting cell) cyto alanine (Ala): an amino acid present in almost all proteins chem alate: winged bot albido: the white tissue beneath the peel of citrus bot albinism: in plants, a deficiency of chromoplasts bot albino: a plant lacking chromoplasts bot albumen: starchy and other nutritive material in a seed, stored as endosperm inside the embryo sac, or as perisperm in the surrounding nucellar cells; in general, any deposit of nutritive material accompanying the embryo phys >>> endosperm >>> albumin(e)

albumin(e): any of certain proteins soluble in distilled water at neutral or slightly acid pH and in dilute aqueous salt solution; they coagulate by heat

(e.g., leucosins in cereal grains, ricin in rice, or legumelins in pulse seeds, which are mainly enzymes) chem >>> Table 15

albuminoid: containing or resembling albumen or albumin bot albuminous seed: a seed having a well-developed endosperm or perisperm seed >>> Table 15

alepidote: having no scales of scurf, smooth bot aleurodid >>> whitefly aleuron(e): a granulated protein that forms the outermost layer of a cereal grain bot >>> aleuron(e) grain >>> Table 15

aleuron(e) grain: small protein grains present in cells of storage tissue bot aleuron(e) layer: a layer of cells below the testa of some seeds (e.g., cereals), which contains hydrolytic enzymes (e.g., amylases and proteases) for the digestion of the food stored in the endosperm; the production of enzymes is activated by gibberellins when the seed is soaked in water prior to germination bot aleuroplast: a leucoplast in which protein granules are present as a main storage product bot alien addition line: a line of plants with one or more extra chromosomes of an alien species cyto alien chromosome: a chromosome from a more or less related species transferred to a crop plant cyto alien chromosome transfer: cytogenetic methods that facilitate the transfer of individual chromosomes from one species to another meth cyto alien gene transfer: the transfer of genes between species or genera by different means gene biot alien germplasm: genes introduced from a wild relative or nonadapted species cyto gene alien substitution line: a line of plants in which one or more alien chromosomes from a certain donor species replace one or more chromosomes of a recipient species cyto aliquot: a part, such as a representative sample, that divides the whole without a remainder; two is an aliquot of six because it is contained exactly three times; loosely it is used for any fraction or portion prep alkali: a substance capable of furnishing hydroxyl-OH ions to its solution; the most important alkali metals are potassium and sodium chem alkaline phosphatase: an enzyme that is a member of hydrolases; it cleaves from linear DNA or RNA molecules the 5'-terminal phosphate group; dephosphorylated 5' DNA or RNA ends cannot be joined by ligase to 3' ends; polynucleotide kinase reverses the reaction; sometimes used as a biochemical marker in genetic studies phys biot gene alkaline soil: specifically a soil with pH value > 7.0 caused by the presence of carbonates of calcium, magnesium, potassium, and sodium; commonly used for soils showing a pH value 8.5 agr alkaloid: one of a group of basic, nitrogenous, normally heterocyclic compounds of a complex nature; alkaloids occur in several plants (e.g., coniine in hemlock, morphine in poppy fruits, strychnine in seeds of Strychnos nux vomica, atropine in nightshades, colchicine in meadow saffron, caffeine in coffee and tea, nicotine in tobacco leaves, theobromine in cacao) chem phys alkaloidity: the alkaloid content of cell, tissue, organs or individuals of plants phys alkylating agent: a chemical agent that can add alkyl groups (e.g., ethyl or methyl groups to another molecule; many mutagens act through alkylation)

chem allele: one of two or more alternate forms of a gene occupying the same locus on a particular chromosome; currently, different alleles of a given gene are usually recognized by phenotype rather than by comparison of their nucleotide sequences gene >>> allelism allele frequency: a measure of the commonness of an allele in a population of alleles gene >>> allele allele shift: a modification of allele frequency in a population due to either natural or artificial selection gene allele trend: a directed change in allele frequency of populations per time unit gene allele-specific associated primers (ASAP): a PCR variant in which the sequence of the deca-mer oligo is derived from normal RAPD, which generated an absence and/or presence polymorphism; these polymorphisms do not require electrophoretic separation of the sample; the presence of an amplification product is detected by measuring fluorescence of ethidium-bromide stained DNA (Gu et al., 1995) biot allele-specific oligo (ASO): a special kind of oligo for an AC-PCR reaction; the sequence of the oligo is designed in such a way to allow and/or inhibit hybridization at the spot where the mutant (resistant) allele differs from the wildtype (susceptible) allele biot allelic complementation: the production of a nonmutant phenotype when two independent mutations at the same gene locus, but on different homologous chromosomes, are introduced gene allelism: the common shortening of the term "allelomorphism"; one of the two or more forms of a gene arising by mutation and occupying the same relative position (locus) on homologous chromosomes gene allelobrachial: changes of chromosome structure in which the arms of homologous chromosomes are included cyto allelogenous: females that produce only males or only females in different progenies bot allelomorph: a term that is commonly shortened to "allele" gene >>> allele allelopathy: chemical substance released into the environment by an organism that acts as a germination or growth inhibitor to another organism eco allelotype: the genetic composition (i.e., allele frequency) of abreeding population gene alliaceous: onionlike in smell or form bot allocompetition (intergenotype competition): cultivation at high plant density implies the presence of strong interplant competition eco; the individual plants, clones, lines, or families are evaluated when being subjected to intergenotypic competition; also called intergenotype competition stat allocycly: differences in chromosome coiling caused by environmental or genotypic effects cyto allodiploid: cells or individuals in which one or more chromosome pairs are exchanged for one or more pairs from another species cyto allogamous: cross-fertilizing in plants, as opposed to autogamous bot >>> Table 35

allogamy: cross-fertilization as opposed to autogamy bot >>> Table 35 allogene >>> recessive allele allogenetic: cells or tissues related but sufficiently dissimilar in genotype to interact antigenically phys allogenic: applied to successional change due to a change in abiotic environments eco allograft: a graft of tissue from a donor of one genotype to a host of a different genotype but of the same species hort allohaploid: a haploid cell or individual derived from an allopolyploid and composed by two or more different chromosome sets cyto >>> Figure 3

alloheteroploid: heteroploid individuals or cells whose chromosomes derive from various genomes cyto >>> Figure 3

alloiogenesis: growth of a part of an organism in relation to the growth of the whole organism or some other part of it phys allometric: growth in which the growth rate of one part of the plant differs from that of another part or of the rest of the plant bot allometry >>> alloiogenesis allopatric: applied to species that occupy separate habitats and that do not occur together in nature (cf parapatric and sympatric) eco allophene: a phenotype not due to the mutant genetic constitution of the cell or the tissue in question; such a cell or tissue will develop a normal phenotype if it is transplanted to a wild-type host gene allophenic: characteristics that arise by intercellular gene action gene alloplasmic: an individual having the common nucleus, but an alien cytoplasm (e.g., alloplasmic rye containing a wheat cytoplasm); usually leads to meiotic disturbances and sterility gene alloploid (allopolyploid): a plant that arises after natural or experimental crossing of two or more species or genera; they may contain genomes of the parents in one or more copies cyto >>> amphiploid >>> Figures 3, 8

alloploidy >>> alloploid >>> allopolyploid allopolyploid: plants with more than two sets of chromosomes that originate from two or more parents; the sets contain at least some nonhomologous chromosomes cyto >>> Figure 3 >>> Table 17

allopolyploidy >>> allopolyploid allosome: a chromosome deviating in size, form, or behavior from the other chromosomes (autosomes), such as the sex chromosome or B chromosome cyto >>> heterochromosome allosteric: an enzyme whose activity is altered when its structure is distorted by an organic compound at a nonsubstrate site phys chem allosteric effect: the binding of a ligand to one site on a protein molecule in such a way that the properties of another site on the same protein are affected chem allosteric transition: a change from one conformation of a protein to another conformation chem allosubstitution: the replacement of a chromosome or chromosome arm by an alien chromosome or chromosome arm cyto allosynapsis >>> allosyndesis allosyndesis: chromosome pairing of completely or partially homologous (homoeologous) chromosomes cyto allotetraploid syn amphidiploid: a plant that is diploid for two genomes, each from a different species cyto >>> Figure 8

allotetraploidy >>> allotetraploid allotopic: a type specimen of the sex opposite that of the holotype bot; in immunology, an antibody that acts as an antigen to other antibodies of the same species that have variant molecular sites meth allozygosity: homozygosity in which the two alleles are alike but unrelated gene allozygote: a zygote heterozygous for different mutant alleles gene allozyme: isoenzymes of protein nature whose synthesis is usually controlled by codominant alleles and inherited by monogenic rations; they show a specific banding pattern if separated by electrophoresis phys >>> Table 29

alluvial soil: soils developed on fairly recent alluvium (a sediment deposited by streams and varying widely in particle size); usually they show no horizon development agr alpha amylase >>> falling number alpha complementation (of beta-galactosidase): pUC18 and similar vectors contain only a small part of the whole gene for beta-galactosidase; this small part gives rise to a truncated protein that forms an enzymatically active hetero dimer with a specific mutant beta-galactosidase biot alpha helix: the right-handed, or less commonly left-handed, coillike configuration of a polypeptide chain that represents the secondary structure of some protein molecules gene alpha level >>> significance level alpha-bromonaphthalene: a chemical agent that is used for artificial chromosome condensation; for several hours root tips are treated with a saturated water solution prior to staining cyto

Alternaria: a genus of fungi; it forms yellowish-brown conidia that are divided by transverse and longitudinal septa; there are many species, including important plant pathogens (early blight of potato, Alternaria solani; black rot of carrot and rape, A. radicina and A. brassica; Alternaria of wheat) phyt alternate: not opposite to each other on the axis, but borne at regular intervals at different levels (e.g., of leaves) bot alternate host >>> alternative host alternate segregation: at meiosis in a reciprocal translocation heterozygote, the segregation of both normal chromosomes to one pole and both translocated chromosomes to the other pole, giving genetically balanced gametes, or segregation of centromeres during meiosis in a reciprocal translocation heterozygote such that genetically balanced gametes are produced cyto alternating dominance: a change of dominance from one allele to the other (A1a2 ^ a1A2) of a pair of alleles during ontogenetic development of a heterozygous hybrid; the phenotypic expression of the alleles acts one after another gene alternation of generation: the alternation of two or more generations, reproducing themselves in different ways (i.e., alternation of gametophyte [sexual reproductive] and sporophyte [asexual reproductive] stages in the life cycle of a plant) bot alternative disjunction: the distribution of interchange chromosomes at anaphase I of meiosis is determined by their centromere orientation; in the case of alternative disjunction, chromosomes located alternatively in the pairing configuration are distrubuted to the same spindle pole, as opposed to adjacent disjunction cyto >>> adjacent disjunction >>> translocation alternative host: a host that harbors a pest or disease while the primary host is absent or out of season phyt >>> host

Alu element: a repetitive DNA element approximately 300 base pairs long that is abundantly dispersed throughout the genome of primates; the name derived from the AluI restriction enzyme cleavage site that is within most Alu elements biot aluminum (Al): has no specific importance in the metabolism of higher plants; small amounts of uptake favor the imbibition of the cytoplasm; higher concentrations in the soil may cause severe inhibition of plant growth; aluminum tolerance is a main task of plant breeding in several regions of the world chem phys agr >>> Table 33

AMBA >>> American Malting Barley Association amber codon: amber suppresser mutation that changes anticodon of amino acid-carrying tRNA to UAG biot ambisexual: a plant that has the reproductive organs of both sexes bot >>> bisexual ambivalent gene: genes with both advantageous and disadvantageous effects gene ambosexual >>> ambisexual ameiosis: the failure of meiosis and its replacement by nuclear division without reduction of the chromosome number cyto ameiotic parthenogenesis: parthenogenesis in which meiosis has been entirely suppressed gene cyto >>> parthenogenesis ament(um) >>> catkin amidase: an enzyme that catalyzes the hydrolysis of an acid amide chemphys amide: a compound derived from ammonia by replacement of one or more of the hydrogens with organic acid groups chem amine: an organic base derived from ammonia by replacement of one or more of the hydrogens with organic radical groups chem amino acid: an organic compound containing an acidic carboxyl group (-COOH) and a basic amino group (NH2); amino acid molecules combine to form proteins; they are the fundamental constituent of living matter; they are synthesized by autotrophic organisms, such as green plants chem amino acid sequence: the sequence of amino acid residues in a polypeptide chain that represents the primary structure of a protein; the sequence is unique to each protein and influences the protein structure (secondary, tertiary, quaternary) gene

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