Antigenicity antigen

antimetabolite: a substance that resembles in chemical structure some naturally occurring compounds and which specifically antagonizes the biological action of such compounds phys antimitotic: substances that may lead to the cessation of mitosis cyto antimorph: a mutant allele that acts in a direction opposite to the normal al-lele gene >>> amorph >>> hypermorph >>> neomorph antimutagenic: substances that can reduce the rate of mutations gene antimutator gene: mutant genes that decrease the mutation rates gene antinutritive character: a crop product containing substances causing either diseases or negative influences in humans and animals (e.g., the pentosans of rye and triticale) agr antioxidant: a substance that inhibits oxidation chem antipodal cells: three haploid nuclei that are formed during megasporo-genesis in plants; all are located opposite the micropylar end of an ovule bot >>> Figures 25, 35

antipodal nuclei: three of the eight nuclei that result from the megaspore by mitotic cell divisions within the developing megagametophyte (embryo sac); they are usually located at the base of the embryo sac and have no apparent function in most species bot >>> Figure 25

antipodes >>> antipodal cells antisense DNA: noncoding DNA of one of the double-stranded DNA, as opposed to sense DNA, which is the coding DNA (i.e., which is transcribed as mRNA) gene biot antisense gene: a gene construct placed in inverted orientation relative to a promoter; when it is transcribed it produces a transcript complementary to the mRNA transcribed from the normal orientation of the gene biot antisense RNA: a complementary RNA sequence that binds to a naturally occurring (sense) mRNA molecule; in this way it thus blocks its translation biot antiserum: a serum that contains antibodies meth antixenosis: a nonhost preference by the pest; estimated by the degree of colonization on the plants phyt anucleolate: without a nucleus cyto

AOSA: Association of Official Seed Analysts apatite: an important inorganic phosphate of soil, but only of limited use for plant nutrition chem agr aperture: in an optical instrument, the opening of a lens micr aperture diaphragm: an adjustable diaphragm in illumination path that regulates amount of excitation intensity (numerical aperture of excitation light)

micr aperture plane: in a microscope adjusted for KOEHLER illumination, the conjugate planes that include the light source, the condenser iris diaphragm, the objective lens back aperture, and the eye point micr apetalous: a plant showing no flowers bot apex: extreme point or distal end bot apex culture >>> shoot-tip culture apex of the leaf >>> leaf tip aphid vector: any of numerous tiny soft-bodied insects of the family Aphididae transferring viruses phyt aphids: any of numerous tiny soft-bodied insects of the family Aphididae that suck the sap from the stems and leaves of various plants; they are also called plant louses zoo phyt aphyllous: leafless; applied to flowering plants that are naturally leafless (e.g., many species of cactus) bot aphylly: leafnessness bot apical: at the end; related to the apex or tip bot apical cell: a meristematic initial in the apical meristem of shoots or roots of plants; as this cell divides new tissue is formed bot apical dominance: a condition in plants where the stem apex prevents the development of lateral branches near the apex phys apical meristem: an area of actively dividing cells at the tip of a shoot, branch or root; it is also the precursor of the primary tissue of root or shoot bot apical placentation: a type of precentral placentation in fruit where the seeds are attached near the top of the central ovary axis bot apical segment (of spike): the uppermost segment of the rachis bot apical spikelet: the spikelet occurring at the apex (tip) of the ear or panicle bot apiculture: beekeeping for the sale of honey and for pollination of crop plants seed aplanate: lying in a plane; leaves may be displayed on the twigs of a plant to give aplanate foliage; flattened bot apoamphimict: a plant that reproduces predominantly by apomixis but also sexually bot apocarp >>> apocarpy apocarpy: the condition in which the female reproductive organs (carpels) of a flower are not joined to each other (e.g., in buttercup) bot >>> syncarpy apochromat: a microscope objective corrected for spherical and chromatic aberration micr apoenzyme: the portion of a conjugated enzyme that is a protein phys apogamety: autonomous development of a vegetative cell, not the egg cell, into an embryo in an apomict bot apogamy: a type of apomixis involving the suppression of gametophyte formation so that seeds are formed directly from somatic cells of the parent tissue bot >>> apogamety >>> Figure 28

apomeiosis: sporogenesis without reduction of chromosome number during meiosis and giving rise to apomixis bot apomictic: plants that form asexual progenies bot >>> Figure 28

apomixis: asexual reproduction in plants without fertilization or meiosis bot >>> Figure 28

apomorphy: a derived state of a character that has changed in state in relation to its predecessor bot apophase: the period of postmeiotic reconstruction of the cell cyto apoplast: areas of a plant that lie outside the plasmalemma, such as cell walls and dead tissue of the xylem; the apoplast may represent one of the main pathways of water through the plant bot apoptosis: the process by which a cell dies in a programmed way, or in other words, kills itself; it is the most common form of physiological (as opposed to pathological) cell death; it is an active process requiring metabolic activity by the dying cell; often characterized by shrinkage of the cell and cleavage of the DNA into fragments bot phys apospory: the development of a diploid embryo sac in some plants by the somatic division of a nucellus or integument cell without meiosis; a sort of agamospermy in which a seed is produced without fertilization bot >>> Figure 28

apostatic selection: a selection of very rare genotypes (e.g., a macromutation)

gene apothecium: a roughly cup-shaped or dishlike ascocarp, in which the asci line the inner surface and are thus exposed to the atmosphere bot appendage: a process of outgrowth of any sort bot apple scab: a common disease of apple trees in which the most obvious symptom is the appearance of superficial, dark, corky scabs on the fruit phyt applied genetics: studying genetic factors and processes for utilization in agriculture and other branches of science gene appressed: lying close and flat against bot appressorium: in certain parasitic fungi, an attachment organ consisting of a flattened hypha that presses closely to the tissue of the host as a preliminary stage in the infection process bot aquatic: living in water bot arabinose (Ara): an aldose that contains five carbon atoms; a member of pentoses (e.g., it occurs in sugarbeet) chem phys arable: capable of producing crops by ploughing or tillage agr arable land: land capable of producing crops by ploughing or tillage agr arachin >>> globulin arachnoid: covered with hairs or fibers or formed of hairs or fibers bot arborescent: treelike shape bot archegonium: female sex organ of liverworts, mosses, ferns, and most gym-nosperms; usually a flasklike organ, comprising a swollen base or center containing a single egg cell and a slender elongated neck containing one or more layers of cells bot archesporial: the differentiated cell situated in the nucellar tissue of the ovule that is destined to undergo meiosis and give rise to the haploid generation bot archesporium: cells formed by mitosis of the micro- and macrospore mother cells bot arcuate: curved or arched bot arginine (Arg): an aliphatic, basic, polar amino acid that contains the guanido group chem phys arid: dry climates or dry regions (<250 mm rainfall in temperate climates and <350 mm rainfall in tropical climates); commonly applied to a region or a climate in which precipitation is too low to support crop production eco aril(lus): a usually fleshy and often brightly colored outgrowth from the funicle or hilum of a seed, a third integument; arils probably often aid seed dispersal by drawing attention to the seed after the fruit has dehisced and by providing food as an attractant and reward to the disperser bot arista >>> awn aristate: showing awns; bearded; bristle tipped bot >>> Figure 34

arithmetic mean: an average; the number found by dividing the sum of series by the number of items in the series stat arnautka: strains of durum wheat (Triticum durum) agr >>> Table 1 arrect: stiffly upright bot arrhenotoky: in insects (e.g., bees), the development of male progenies from nonfertilized eggs zoo arrow: the inflorescence of sugarcane agr arsenic: it may be found in plants in very low dosage; higher concentrations in soil may be toxic for plants chem agr articulate: jointed; having a node or joint bot artifact: a human-made object; something observed that usually is not present but that has arisen as a result of the process of observation or investigation meth artificial chromosome: a chromosome experimentally created and constituted, in addition to genetically coding DNA sequences, by ligating origin of replication, autonomous replicating sequences, and telomeric and centromeric sequences biot artificial light: light other than sunlight; often from fluorescent tubes; used to grow plants in greenhouses or growing chambers usually out of season hort agr artificial seeds: based on embryogenic suspension cultures, embryos may be coated with water-soluble hygrogels and other substances in order to guarantee a proper germination even under field conditions seed biot artificial selection: plant selection by human or agronomic means artioploid: it refers to polyploids with even sets of genomes cyto

ASAP >>> allele-specific associated primers ascendent >>> ancestor ascending: rising somewhat obliquely, or curved upward bot ascogonium: the female gametangium of some fungi bot ascorbic acid: the water-soluble vitamin C that occurs in large quantities in fruits and vegetables chem phys ascospore: a sexually produced, haploid spore formed within an ascus by some fungi bot ascus: a minute, baglike structure within which ascospores develop in some fungi bot aseptic: free from living microorganisms or pathogens; sterile pre asexual: any reproductive process that does not involve the fusion of gametes bot >>> Figure 28

asexual reproduction: a propagation without formation of zygotes by sexual organs and genetic recombination; in plants, there are two types of asexual reproduction: vegetative propagation (by stolons, rhizomes, tubers, tillers, bulbs, bulbils, or corms) and apomixis (by vegetative proliferation or agamospermy) bot >>> Figure 28

ASO >>> allele-specific oligo asparagine (Asn): an amino acid found in storage proteins of plants (e.g., in peas and beans); the designation derived from the presence in asparagus chem phys asparagus knife: a tool for prying and pulling out long-rooted plants syn dandelion weeder syn fishtail weeder hort aspartic acid (Asp): an aliphatic, acidic, polar alpha-amino acid chem phys aspirator: an air-blast separator; a seed conditioning (cleaning) machine that uses air to separate according to specific gravity (weight) and resistance to air flow seed >>> Table 11

assimilation: in plant physiology, the production of an organic substance from anorganic elements and compounds via photosynthesis phys >>> carbon dioxide assortative mating: occurs if the plants mating resemble each other, with regard to some traits gene >>> disassortive mating

ASTA: American Seed Trade Association asymmetric fusion: a cell formed by the fusion of dissimilar cells; referred to as a heterokaryon biot >>> cell fusion asynapsis: chromosomes of meiosis I in which pairing either fails or is incomplete cyto

42 Encyclopedic Dictionary of Plant Breeding and Related Subjects asynaptic >>> asynapsis asyndesis >>> asynapsis atavism: the reappearance of a character after several generations; the reversion to an ancestral or earlier type of character; the character being the expression of a recessive gene or of complementary genes bio atrophy: reduced or diminished organ size, shape, or function, usually a deteriorate change bot phys atropine: a poisonous crystalline alkaloid, C17H23NO3, it can be extracted from deadly nightshade and other solanaceous plants; used in medicine to treat colic, to reduce secretion, and to dilate the pupil of the eye chem phys att site: loci on a phage and the bacterial chromosome at which site-specific recombination takes place biot attar: a term used for a perfume from flowers (an essential oil, e.g., the attar of roses) hort attenuator: a nucleotide sequence, located in the leader region between the promoter and the structural genes of some operons, that causes RNA polymerase to cease transcription in the leader region before transcribing the structural genes of the operon gene biot atypical: having no distinct typical character; not typical; not conformable to the type meth auger: a tool for boring a hole in the soil; used in planting or transplanting seeds, seedlings, or bulbs or in fertilizing shrubs, trees and ground covers prep hort; in seed production, a long pipe with a twist inside to carry the grain up into a grainery seed auricle: clawlike outgrowth arising at the junction of the leaf blade and sheath (e.g., present in wheat and barley, absent in oats) bot >>> Table 30

auriculate: furnished with auricles bot >>> auricle aurofusarin: an orange-yellow pigment of the fungus Fusarium culmorum phyt

Bee Keeping

Bee Keeping

Make money with honey How to be a Beekeeper. Beekeeping can be a fascinating hobby or you can turn it into a lucrative business. The choice is yours. You need to know some basics to help you get started. The equipment needed to be a beekeeper. Where can you find the equipment you need? The best location for the hives. You can't just put bees in any spot. What needs to be considered when picking the location for your bees?

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