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Paris green: a very nasty pesticide containing copper and arsenic, which was widely used until replaced with DDT phyt
parthenote: a cell or individual resulting from parthenogenesis cyto
partially balanced design (partially balanced incomplete block design) - teilweise balancierte Versuchsanlage f:
a design is partially balanced with respect to an association scheme if the number of blocks containing two points depends only on which class of the partition contains the given pair of points stat
partially balanced incomplete block design (PBIB):
it refers to an experimental design where the residual variance of the difference between the candidates may adopt one out of only two different values stat meth >>> partially balanced design
partial Latin square: an n x n array whose cells are either empty or contain a symbol from an alphabet of size n, such that
each symbol occurs at most once in each row or column, e.g., a >>> Latin rectangle stat
pasteurization:
named after the French L. PASTEUR; a technique of heating wine, milk, food, or soil to about 80 °C in order to destroy harmful >>> microorganisms; this temperature does not lead to a complete sterilization, for which a temperature of about 120 °C is required meth phyt
PBCC >>> Plant Breeding Coordinating Committee
..... more on CD-ROM
pedology: the science of soils, including their classification, formation, structure, and composition agr
perennial:
a plant that normally lives for more than two seasons and that, after an initial period, produces flowers annually; among perennial crops are: oil palm, cacao, rubber tree, rye grass, tall fescue, alfalfa etc bot
persistence: the act or fact of persisting phyt
persistent >>> persistence
persistent modification: nonheritable morphological or physiological changes over a more or less long period of generation cycles induced by
varying abiotic or biotic influences gene
pest: any form of plant or animal life, or any pathogenic agent, injurious or potentially injurious of plants or plant products phyt
pest resistance: resistance to any form of plant or animal life or any pathogenic agent phyt
pesticide: a chemical preparation for destroying plant, fungal, or animal pests phyt
petal: one of the inner floral leaves, usually brightly colored and borne in a tight spiral or whorled carolla bot
petiole: the stalk by which a leaf is attached bot
PETRI dish: a covered glass container in which cells, organs, seeds, or microorganisms are cultured prep
P1 generation >>> parental generation
PGIPs >>> polygalacturonase-inhibiting proteins
phage: the abbreviation for bacteriophage (i.e., a virus that infects bacteria) bio
phase-contrast microscopy:
light rays passing through an object of high refractive index that will be retarded in comparison with light rays passing through a surround medium with a lower refractive index; the retardation or phase change for a given light ray is a function of the thickness and the index of refraction of the material through which it passes; thus in a given unstained specimen, transparent regions of different refractive indexes retard the light rays passing through them to differing degrees; such phase variations in the light focused on the image plane of the light microscope are not visible to the observer; the phase contrast microscope is an optical system that converts such phase variations into visible variations in light intensity or contrast; it allows observation of the cell and structures (even living) without staining and degrading treatments micr
phasmid:
a cloning vector that has the possibilities to replicate as a plasmid or as a phage; the two modes of replication are usually functional in different bacterial species biot
phellogen: a layer of plant tissue outside of the true cambium, giving rise to cork tissue bot
phene:
the phenotype of the plant, which is a product of the gene (gene > DNA > transcription > RNA > processing > translation > protein) and the interaction with the environment gene >>> phenotype
phenocopy:
a nonhereditary phenotypic change that is environmentally induced during a limited developmental phase of an organism; it may mimic the effect of a known genetic mutation gene
phenogenetics: a branch of genetics that studies the interaction of the genotype and its manifestation gene
phenol: a chemical used to remove proteins from DNA preparations biot
phenol test (reaction): the color produced in the grain of, for example, wheat and barley, by treatment with a one percent solution of phenol in
water seed meth
phenology: the study of the impact of climate on the seasonal occurrence of flora eco
phenotype:
the observable manifestation of a specific genotype (i.e., those properties on an organism, produced by the genotype in conjunction with the environment) gene
phenotypic expression: the manifestation of a particular gene resulting in a particular phenotype gene
phenotypic plasticity: the capability of a genotype to assume different phenotypes gene
phenotypic segregation:
the phenotypic differentiation patterns of cells or individuals in segregating populations, as opposed to genetic segregation gene >>> Table 2
phenotypic selection: development of a variety based on its physical appearance without regard to its genetic constitution gene
phenotypic variance (VP): the total variance observed in a character; it includes experimental error, genotype × environment interaction
and the genotypic variance stat
phenylalanine (Phe): an aromatic, nonpolar amino acid chem phys
pheromone:
a chemical exchanged between members of the same animal species that effects behavior (sex attractants, alarm substances, aggregation-promotion substances, trail substances, etc.) phyt bio
Ph locus: a gene that controls homoeologous chromosome pairing in wheat and, similarly, in other allopolyploid plants; the Ph gene
restricts pairing between homologous chromosomes in a polyploidy; during evolution a subtelomeric heterochromatin block became inserted into a group of cdc2-like genes on 5B; Ph1 is involved in the regulation of chromatin condensation; it seems likely that this insertion event generated a functional and/or regulatory change at the 5B cdc2-like gene family gene
phloem:
a tissue comprising various types of cells that transports dissolved organic and inorganic materials over long distances within vascular plants bot
phosphatase: an enzyme that catalyzes reaction involving the hydrolysis of esters of phosphoric acid chem phys
phosphorus (P): an element that is required by plants in the oxidized form; it is utilized in reactions in which energy is transferred,
often involving ATP chem phys >>> mitochondrion
phosphorylation: the addition of a phosphate group to a compound, involving the formation of an ester bond between the reactants phys
photobleaching:
photochemical reaction of fluorophores, light, and oxygen that causes the intensity of the fluorescence emission to decrease with time micr
photoinhibition: the slowing or stopping of a plant process by light (e.g., the germination of some seeds) phys
photo-insensitive plants >>> daylength insensitivity
photometry: the measurement of the intensity of light or of relative illuminating power meth micr
photomorphogenesis: changes in plant growth due to light; there is a main plant regulator protein Cop1 that suppresses genes controlling the
photomorphogenesis; for example, when a seedling gets exposed to light the Cop1 protein is reduced in the nucleus and photosynthesis is initiated—the seedling becomes green; cryptochromes may interact with
photoreceptor-proteins, which can recognize blue light; thus the interaction can “switch-off” the Cop1 protein phys
photon: a packet of light energy phy
photonasty >>> nasty
photoperiod:
the relative length of the periods of light and darkness associated with day and night; in many species, floral induction occurs in response to daylength; species have been categorized according to their daylength requirements as short-day, long-day, intermediate-day, or day-neutral phys
photoperiodism: the response of a plant to periodic, often rhythmic, changes in either the intensity of light or to the relative length of day phys
photoreceptor: a pigment that absorbs the light used in various metabolic plant processes that require light phys
photosynthesis:
the series of metabolic reactions that occur in certain autotrophs, whereby organic compounds are synthesized by the reduction of carbon dioxide using energy absorbed by chlorophyll from light phys >>> Table 33
pH value: the negative logarithm of the hydrogen-ion activity, expressed in terms of the pH scale from 0-14 chem
phyletic:
the evolution by which a race or line is progressively transformed from its ancestral form without branching or separating into related parts evol
phyletic gradualism: the process of gradual evolutionary change over time evol
phyletic series >>> phyletic
phyllode: an expanded petiole resembling and having the function of a leaf, but without a true blade bot
phyllody: the condition in which parts of a flower are replaced by leaf-like structures; often it is a symptom of certain diseases bot
phyllosphere: the surface of a living leaf bot
phyllotaxis: the active arrangement of leaves on a stem or axis bot
phyllotaxy >>> phyllotaxis
phylogenesis >>> phylogeny
phylogenetic: of, pertaining to, or based on phylogeny evol
phylogenetic tree: a diagram showing evolutionary lineages of organisms evol
phylogeny:
evolutionary relationships within and between taxonomic levels, particularly the patterns of lines of descent, often branching, from one organism to another evol >>> Figure 10 >>> Tables 1, 14, 17, 49, 50
phylum (phyla pl): an important group of organisms bot
physical map:
map of the locations of identifiable landmarks on DNA (e.g. restriction enzyme cutting sites, genes) regardless of inheritance, the distance is measured in base pairs >>> mapping
physiological races: pathogens of the same species with similar or identical morphology but differing pathogenic capabilities phyt
physiologic specialization:
the existence of a number of races or forms of one species of pathogen based on their pathogenicity to different cultivars of a host phyt
physiological maturity: the maturity of a seed when it reaches its maximum dry weight; this usually occurs prior to the normal harvest date seed
physiological race: pathogens of the same species with similar or identical morphology but differing pathogenic capabilities phyt
physiologist: a specialist dealing with the functions and activities of living organisms and their parts phys
phytase: an enzyme that catalyzes the breakdown of phytin, the source of inorganic phosphorus in seed metabolism chem phys >>> phytic acid
phytic acid:
a myo-inositol 1,2,3,4,5,6-hexakisphosphate and the major storage compound of phosphorous in plants, predominantly accumulating in seeds (up to 4-5 % of dry weight) and pollen; in cereals, phytic acid is deposited in embryo and aleurone grain tissues as a mixed "phytate" salt of potassium and magnesium, although phytates contain other mineral cations, such as iron and zinc; during germination, phytates are broken down by the action of >>> phytases, releasing their phosphorous, minerals and myo-inositol, which become available to the growing seedling; phytic acid represents an anti-nutritional factor for animals phys
phytoalexin(e): an antifungal substance that is produced by a plant in response to damage or infection phyt phys
phytochrome:
a photoreversible pigment that occurs in every major taxonomic group of plants; it exists in two interchangeable forms with respect to absorption, a red and a far-red form; Pr phytochrome is receptive to orange-red light (600-680 nm) and inhibits flowering; Pf-r phytochrome is receptive to far-red light (700-760 nm) and induced flowering phys
phytogenetics: synonymous to plant genetics, dealing with inheritance in plants gene
phytohormone >>> plant hormone
phytoncide >>> herbicide
phytopathology: the study of plant diseases phyt
phytosanitary certificate:
a certificate from a recognized plant quarantine service that indicates that a sample is substantially free from diseases or pests seed
phytosiderophore(s): nonproteinogenic amino acids developed by plants under conditions of mineral deficiency (especially under iron and
zinc deficiency); the production and exudation of phytosiderophores is controlled by several genes; there are crop plants, such as rye, showing a high level of phytosiderophore production and/or exudation toward
the rhizosphere phys
phytotoxic: being poisonous to plants phyt
phytotoxin >>> pathotoxin
phytotron - Wachstumskammer f:
a group of rooms or a room for growing plants under controlled and reproducible environmental conditions prep meth
pick-up reel: a special device on some harvesters for taking up lodging straw agr
picotee: a type of edging on a daylily flower where the edge is a completely different color than the tepals hort
pigment - Farbkörber m: an organic compound that produces color in the tissue of the plant bot
pileorhiza >>> root cap
piliferous layer >>> root hair
pilose: hairy bot
pilosum: used for describing a hairy ventral furrow, for example, barley grain bot
pilot test: preliminary test or study of the program or evaluation activities to try out procedures and make any needed changes or adjustments stat meth
pin flower: flowers with long styles and short stames bot >>> Table 18
pincers - Pinzette f: a gripping tool consisting of two pivoted limbs forming a pair of jaws and a pair of handles prep
pinching (pinching back, pinching out) >>> disbud
pinna: one of the leaflets of a pinnate leaf bot
pinnate - gefiedert adj: feathered, i.e., a compound leaf that has leaflets arranged on either side of a stalk bot
pinnate leaf >>> pinnate
pinninervate: pinnate-veined; feather-veined bot
pipette: a slender, graduated tube for measuring liquids or transferring them from one container to another prep
pistil: the gynoecium of a syncarpous flower; a pistil includes an ovary, style, and stigma; the stigma is the receptor of the pollen bot >>> Figure 35
pistillate flower: designating a flower having one or more pistils and no stamens bot
pistillody: the conversion of any organ of a flower into carpels (e.g., stamens into pistils or pistillike structures) bot >>> pistillate flower
pistillum >>> pistil
pit: in botany, a term used for the widening in the center of the ventral furrow in some wheat and barley grains bot
pith: a tissue that occupies the central part of a stem (composed of parenchyma cells) bot
pixel: a picture (pix) element (el); it refers to points of information used to map images; pixels exist in arrays with specific x-
and y-coordinates phy meth
placenta: the part of the ovary wall formed from the fused margins of the carpel or carpels on which the ovules are carried bot
placentation:
the position of the placenta within the carpel; it may be parietal (on the walls), axile (on the axis), basal (on the basis), or free-central bot
plan apochromatic objective lens (plan apo): a modern, high-resolution microscope objective lens designed with high degrees of corrections for
various aberrations; it is corrected for (1) spherical aberration in four wavelengths (dark blue, blue, green, red), (2) for chromatic aberration in more than these four wavelengths, and (3) for flatness of
field; a single plan apo may contain as many as 11 lens elements micr
plantation:an area under cultivation; a closely set stand of trees or special crops that has been planted by humans; a large estate or farm on
which crops are raised, often by resident workers; a newly established settlement or a colonyagr hort
plant breeder: a person or organization actively engaged in the breeding and maintenance of varieties of plants, applying a wide range of methods
of different scientific disciplines
plant breeding:
the application of genetic principles and practices to development of individuals or cultivars more suited to the needs of humans; it uses knowledge from agronomy, botany, genetics, cytogenetics, molecular genetics, physiology, pathology, entomology, biochemistry, statistics, etc.
Plant Breeding Coordinating Committee (PBCC):
it serves as a forum regarding issues and opportunities of national and global importance to the public and private sectors of the USA national plant breeding effort; office at Raleigh (North
Carolina State University), USA org
plant density: the rate at which seed or vegetative propagules are placed in a field or experimental planting meth agr
plant hair >>> trichome
plant hormone:
a compound that is synthesized by a plant, but is not a nutrient, coenzyme, or detoxification product, and which regulates growth, differentiation or other specific physiological processes phys
plantibodies: antibodies produced in transgenic plants expressing the antibody-producing gene(s) of an animal, e.g., mouse, that had been
previously injected with a pathogen (usually a virus) and that infects the plants phyt biot
planting cord: a string of different manufacturing and length used for marking experimental plots, paths, margins between landmarks or applied to
mark planting rows prep
plant label: plastic, wood, or other stakes for gardens or experiments to indicate what seeds or material are planted where until they appear,
which varieties are included, what sort of evaluation is carried out, etc.; in plant conservation, paper forms to include in drying plant samples, with formal printed forms as permanent labels on herbarium
specimens; the minimum information includes the name of the collector, the location collected, the date collected, and the correct identification of the specimen meth agr hort
plantlet: a stage of in vitro culture; the stage after torpedo stage and usually one of the last before a whole plant is generated biot
plantling >>> plantlet
plant passport:
an official seed label used for forthcoming marketing; it shows the crop, crop class, e.g., European community grade, inspections, etc. seed >>> passport data
plant pathogenesis-related proteins (PPRP): groups of proteins with different chemical properties produced in a cell within minutes or hours
following inoculation, but all being more or less toxic to pathogens phyt
plant pathology >>> phytopathology >>> biological control
plant protection >>> phytopathology >>> biological control
plant variety protection >>> plant variety rights
Plant Variety Protection Act:
enacted in 1970 in the United States to provide patentlike protection for seed plant species; prior to 1970, breeders in the industry worked primarily with maize and sorghum, with some efforts directed to alfalfa, cotton, sugarbeet, and certain vegetables; the purpose of the PVPA was to stimulate private plant breeding research and to provide better seed cultivars to farmers and gardeners
plant variety rights: the legal rights of a plant breeder (not necessarily as a person) who has developed a new variety seed
plantation: a closely set stand of trees or special crops that has been planted by humans agr hort
plantibodies: antibodies produced in transgenic plants expressing the antibody-producing gene(s) of an animal biot
planting bar: a hand tool used in making a slit-hole in which trees are planted fore hort
planting cord: a string of different manufacturing and length used for marking experimental plots, paths, margins between landmarks, or applied to
mark planting rows prep
plantlet: a stage of in vitro culture; the stage after torpedo stage and usually one of the last before a whole plant is generated biot
plantling >>> plantlet
plant quarantine:
the isolation of newly imported plants to ensure that they are not introducing any foreign parasites; the term quarantine may refer to the quarantine station itself, or to the process of testing and purifying the plant material seed meth
plaque: a circular zone of lysis produced by bacteriophage in a colony of bacteria on an artificial medium meth
plaque lift:
impression of bacteriophage particles blotted to a filter membrane; the technique is used to screen both with radioactively-labeled DNA or RNA probes or with serological screening of eukaryotic expression libraries biot
plasmagene: an extranuclear hereditary determinant showing no Mendelian inheritance gene
plasmalemma >>> cell membrane
plasmatic: all functions, processes, or properties of the cytoplasm bot >>> cytoplasm
plasmic >>> plasmatic
plasmid:
any extrachromosomal hereditary determinant of bacteria; such ring-shaped structures are intensively used for amplification of DNA segment in recent bioengineering approaches; it is capable of self-replication; it can carry genes into a host cell gene >>>
Figure 27
plasmid vector: a plasmid or plasmidlike structure used as a carrier for alien DNA segments or genes biot >>> Figure 27
plasmodesm(a) (plasmodesmata pl): cytoplasmic bridges, lined with a plasma membrane that connect adjacent cells; they provide major
pathways of communication and transport between cells bot
plasmodium: in cellular slime molds, a vegetative structure consisting of a noncellular, mobile mass of naked protoplasm containing many nuclei bot
plasmogamy: the fusion of the cytoplasm of two or more cells after karyogamy during the process of fertilization cyto
plasmolysis:
the result of placing plant cells in a hypertonic solution so that water is drawn out of the cell; the cytoplasm shrinks and the cell membrane is pulled away from the cell wall phys
plasmon: all the extrachromosomal hereditary determinants gene >>> plasmotype
plasmon mutation: a mutation that genetically changes the cytoplasm and/or its hereditary determinants gene
plasmotype: the sum of the extrachromosomal hereditary determinants gene
plastid:
one of a group of double-membrane-bound plant-cell organelles that vary in their structure and function (e.g., chloroplasts, leucoplasts, amyloplasts) bot
plastid DNA: organelle DNA that is present in a plastid gene
plastid inheritance: non-Mendelian inheritance that is caused by hereditary factors present in the plastids gene
plastidome >>> plastome
plastidome mutation: mutations that genetically change the DNA of the plastids of a plant cell gene
plastogene: the hereditary determinants located in the plastid gene
plastome: a term usually used for the plastids of a cell or for the genetic information of the plastid DNA bot gene
plastom mutation >>> plastidome mutation
plate: to place on or in special media in a culture dish prep
plating efficiency:
an estimate of the percentage of viable cell colonies developing on an agar plate relative to the total number of cells spread onto the plate; the plating efficiency is a function of the tissue, medium composition, plating density, and the phase of the stock culture biot
pleiotropic: an allele or gene that affects several traits at the same time gene
pleiotropy: the phenomenon of a single gene being responsible for a number of different phenotypic effects that are apparently unrelated gene
plesiomorphy: ancestral state of a particular character bot
ploidy: the number of complete chromosome sets in the cell nucleus (e.g., diploid, tetraploid, etc.) cyto
plot:
in field experiments, more or less large pieces of land used for planting and evaluation; in forestry, a group of trees, all from the same entry (family, clone, provenance) planted together; a five-tree-plot row is the most common design for forest genetics experiments; in statistics, an experimental unit, to which a single treatment is applied meth agr fore hort stat
plot size:
in field experiments, the size, number, and distribution of plots are essential elements; an efficient combination of plot size and plot number is required; larger plots offer smaller between-plot variance, long measurement time per plot, shorter walking time between plots, less edge, and less statistical error; small plots require a higher number of plots in order to achieve the same level of precision of estimates; plot size and shape vary with crops and stage of testing, and among characters under selection; plots are generally small at the initial stage of testing and reach a maximum size during the second and third years of replicated trials; unbordered plots with few replications at one or few locations are used for traits with low heritability; row spacing and plant populations are chosen to be similar to commercial production of crop; seedbed preparation, fertilization, weed control practices, etc., are generally the same as those used for commercial production; the mechanization and computerization of most plant breeding programs have greatly increased a breeder’s ability to handle more plots, populations, etc. meth stat
plot structure:
the need for experimental design, even when comparing an unstructured set of treatments, is caused by inhomogeneity in the set of plots; a common form of structure consists of one or more partitions; in the case of a single partition a >>> block design is used; for a pair of partitions >>> nested block designs are applied or a row-column design if the partitions are nested or crossed, respectively stat
plumula: the undeveloped shoot consisting of unexpanded leaves and the growing point (i.e., the terminal bud of developed embryo) bot
plurannual >>> perennial
plus tree:
a tree phenotype judged (but not proved by testing) to be unusually superior in some qualities (e.g., growth rate relative to site, growth habit, high wood quality, resistance to disease and insect attack, or to other adverse local factors) fore
pneumatophore: a specialized root in certain aquatic plants that performs respiratory functions bot
pod:
a fruit that dehisces down both sides into two separate valves that are most typically dry and somewhat woody; they are characteristic fruits of the Leguminosae bot >>> legume
pod drop: losses due to the premature drop of pods; phys agr
pod shattering: seed losses due to the premature shattering of pods; for example, in oilseed rape it can be as great as 50 % of the potential
yield in some seasons; average losses are around 10-15 %, equivalent to 500 kg/ha or ten times the sowing rate agr
poikiloploid >>> mixoploid
point mutation:
a mutation that can be mapped to one specific locus; it is caused by the substitution of one nucleotide for another; it may also be caused by deletion and inversion gene
poison >>> toxicity
poisonous >>> toxicity
POISSON distribution:
the basis of a method whereby the distribution of a particular attribute in a population can be calculated from its mean occurrence in a random sample of the population, provided that the population is large and the probability that the attribute will occur is less than 0.1 stat
polar mutation: a mutation of one gene that affects the expression of the adjacent nonmutant gene on one side, but not of that on the other side gene
polar nuclei >>> pole nucleus
polar plate: the functional center for meiotic division of chromosomes; spindle fibers converge on it cyto
polarization: restriction of the orientation of the vibration of electro-magnetic waves of light phy micr >>> polarization microscope
polarization microscope:
a compound light microscope used for studying the anisotropic properties of objects and for rendering objects visible because of their optical anisotropy micr >>> polarization
pole: one of the two ends of the cell spindle toward which chromosomes move during mitotic and meiotic anaphase cyto
pole nucleus (pole nuclei pl): the two haploid nuclei present in the center of the embryo sac after division of the megaspore; they may
fuse to form a diploid definitive nucleus before fusing with the male gamete to form the triploid primary endosperm nucleus prior to double fertilization bot >>> Figure 25
pollard: a tree cut back almost to the trunk in order to form a thick head of spreading branches, which are cut for basket-making and kindling
(e.g., poplars and willows can be pollarded) bot
pollen:
collectively, the mass of microspores or pollen grains produced within the anthers of a flowering plant; it is a highly specialized tissue whose function is the production of two sperm cells and their subsequent delivery through the style and ovary to the embryo sac cells where the double fertilization takes place; it is a highly reduced structure consisting of only three cells; the processes of pollen development, germination, and fertilization involve the specific expression of a large number of genes bot >>> Figure 35
pollen analysis:
a method to study pollen grains, particularly their size, shape, and surface; since those characters are highly specific for species the method is used for taxonomic classifications bot
pollen barrier:
in seed production, the separation of the varieties, lines, etc. (mostly in allogamous crops) in order to prevent intercrossing; it is done by different means, such as strips of other plants (e.g., hemp or maize), which prevent the free flow of pollen, or by isolation walls of tissue seed
pollen contamination:
refers often in connection with seed orchards to the phenomenon that some of the pollen fertilizing orchard genotypes origins outside the seed orchard gene >>> alien pollen >>> pollen migration >>> wild pollen >>> gene flow
pollen culture >>> microspore culture
pollen embryoids: embryoids that derive from anther culture biot
pollen grain:
a microspore in flowering plants that germinates to form the male gametophyte, a structure made up of the pollen grain plus a pollen tube bot >>> Figure 35 >>> pollen
pollen grain mitosis:
in microsporogenesis, a nuclear division that occurs in the pollen grain after the formation of tetrads; it results in a smaller generative nucleus and a larger vegetative nucleus bot
pollen mixing:
cross-incompatibility in interspecific crosses is associated with proteins of the pistil that interact with proteins of the pollen to prevent normal pollen tube germination and growth; this unfavorable reaction may be avoided in certain combinations by mixing pollen from a compatible species with pollen from an incompatible parent meth
pollen mother cell (PMC): the microsporocyte, which undergoes two meiotic divisions to produce four microspores; each microspore becomes a pollen
grain bot
pollen parent: the parent that furnishes the pollen and that fertilizes the ovules of the other parent in the production of seed meth
pollen sac: a sac within the anther of a stamen within which microspores are produced bot
pollen-shedding: the status or process when the pollen grains are released from the anthers bot
pollen sterility: pollen that is not able to fertilize an egg cell phys
pollen transfer: refers to the kind of pollen transfer from the male to female organs (e.g., mediated by wind, insects, by hand, etc.) bot
pollen tube: the tube formed from a germinating pollen grain and down which the two male gametes pass to the ovum bot >>> Figure 35
pollen tube competition >>> certation
pollinarium (pollinaria pl): a functional unit in orchid pollination that consists of two or more pollinia, stalk, or stipe, and a viscidium bot
pollinate:
to transfer pollen from the anther to the receptive surface of the stigma of the same or another flower in angiosperms and from male to female in gymnosperms; this process usually requires a vector in outbreeding plants meth >>> Figure 35
pollination:
the transfer of pollen grains from the anther to the stigma of a flowering plant; pollination can also be done in artificial culture (i. e., in vitro pollination) bot >>> Figure 35
pollinator: that parental individual, line, variety, or species, which is used as a donor of pollen in a cross meth
polyacrylamide gel:
a gel used to separate biological molecules (proteins); it is prepared by mixing a monomer (acrylamide) with a cross-linking agent (N,N'-methylene-bisacrylamide) in the presence of a polymerizing
agent; it leads to the formation of an insoluble three-dimensional network of monomer chains, which become hydrated in water prep
polyacrylamide gel electrophoresis (PAGE): a method for separation of proteins and amino acids on the basis of their molecule size; the molecules
move through the gel under the influence of an electric field meth
polyadenylation:
posttranscriptional addition of 50-200 adenine residues to the 3' end of eukaryotic mRNA; the poly-A tail can be used to separate eukaryotic mRNA from other RNA species with oligo T cellulose biot
polyandrous: having many stamens bot
polyandry:
the state of having more than one male mate at one time; in fertilization, the fusion of one female and two or more male pronuclei within an egg cell bot
polycarpellary: composed of several carpels bot
polycarpic: in general, bearing many fruits (i.e., producing fruit many times or indefinitely); in botany, having a gynoecium forming two
or more distinct ovaries or carpels bot
polycarpous >>> polycarpic
polycentric: a chromosome that shows more than two centromeres cyto >>> centromere
polycistronic RNA: mRNA that codes for more than one polypeptide gene
polycotyledonous embryo(s): embryos having more than two cotyledons or seed leaves (e.g., in pines and conifers) bot
polycross:
open pollination of a group of genotypes (generally selected) in isolation from other compatible genotypes in such a way as to promote random mating inter se; it is a widely used procedure for intercrossing parents by natural hybridization meth >>> Table 35
polycross test: a progeny test to assess general combining ability from crosses among selected parents; identities can be maintained only for the
seed parents; a mixture of pollen is artificially applied to each female parent meth >>> topcross
polyembryonic >>> polyembryony
polyembryony:
the condition in which an ovule has more than one embryo like in certain grasses or cereals; in the past, the phenomenon was used for haploid selection among the embryos, which show often different ploidy levels bot meth >>> Figure 17
polyethylene glycol (PEG): a polymeric substance of molecular weight between 1,000-6,000; it is used for stimulation of protoplast fusion chem biot
polygalacturonase-inhibiting proteins
(PGIPs): leucine-rich repeat (LRR) proteins involved in plant defence system; a number of PGIPs have been characterized from dicot species, whereas only a few data are available from monocots phys biot phyt
polygamous: plants that show male, female, and hermaphrodite flowers on the same or different plants bot
polygenes:
one of a group of genes that together controls a quantitative character; individually each gene has little effect on the resulting phenotype, which instead requires the interaction of many genes gene >>> Table 33
polygenic: of traits determined by many genes, each having only a slight effect on the expression of the trait gene >>> multifactorial >>> Table 33
polygeny: a trait that is controlled by many genes gene >>> Table 33
polygynoecial: having a number of pistils joined together, as in aggregate fruits (e.g., raspberry) bot
polygyny:
the state of having more than one female mate at one time; in fertilization, the fusion of one male and two or more female pronuclei within an egg cell bot
polyhaploid: haploid plant derived from a polyploid individual cyto
polyhybrid:
individuals that are heterozygous with respect to the alleles of many gene loci or of crosses involving parents that differ with respect to the alleles of more loci gene
polykaryotic: cells showing many nuclei cyto
polylinker: synthetic oligonucleotide with recognition sites for several restriction endonucleases biot
polymerase: an enzyme that catalyzes the replication and repair of nucleic acids gene
polymerase chain reaction (PCR) technique:
a technique for continuous amplification of DNA and/or DNA fragments in vitro; the DNA sequence must be known so that oligonucleotides can be synthesized that are complementary to the extremes of the fragment that is to be amplified; heat stable DNA polymerase (e.g., from Thermus aquaticus) is used for DNA synthesis gene
polymeric genes: genes with equal effects but cumulative action gene
polymery: the production of a trait by cooperation among several polymeric genes gene
polymix breeding: an alternative method to full-sib crossing and testing; the alternative solution is to apply a pollen mix of many male parents
rather than a single pollen for each cross; polymix breeding is easy to implement, ensures good estimates of breeding values of the parent being pollinated, and provides for increased genetic gain opportunity
because of the significantly increased number of effective parental combinations tested; however, it has found limited use because inbreeding and pedigree control is lost meth stat
http:// www.geneflowinc.com
polymorphic: occurring in several different forms bot gene
polymorphism:
the existence of two or more forms that are genetically distinct from one another but contained within the same interbreeding population gene
polynemic chromosome: describes metaphase chromosome and/or chromatids with more than two DNA helices cyto
polynucleotide: a sequence of many nucleotides gene
polypeptide: a linear polymer that consists of ten or more amino acids linked by peptide bonds chem
polyphenol oxidase (PPO): it is one of the major enzymes responsible for browning of wheat food products; wheat cultivars differ in
PPO activity and plant breeders wish to select germplasm and cultivars with low PPO activities agr phys
polypheny >>> pleiotropy
polyphylesis: originating from several lines of descent bot
polyphyletic:
designating a group of species arbitrarily classified together, some of the members of which have distinct evolutionary histories, not being descended from a common ancestor evol
polyploid: an individual carries more than two complete sets of homologous chromosomes cyto
polyploidization: the spontaneous or induced multiplication of a haploid or diploid genome of a cell or individual cyto >>> Table 35
polyploidy:
the condition in which an individual possesses one or more sets of homologous chromosomes in excess of the normal two sets found in diploids; it can be produced in nature by somatic doubling due to irregular mitosis in the meristematic cell and by unreduced gametes due to irregular reductional division during meiosis; for example, approximately 70 % of grass species and 20 % of legumes are polyploid cyto >>> Tables 17, 35
polysaccharide: a molecule composed of chains of sugar units phys
polysome: a polyribosome, consisting of two or more ribosomes bound together by their simultaneous translation of a single mRNA molecule gene phys
polysomy: the reduplication of some but not all of the chromosomes of a set beyond the normal diploid number cyto
polyspermy: the entry of more than one sperm cell into an egg cell, irrespective of whether or not the additional sperm cells fertilize bot
polytene chromosome:
a chromosome that is formed by repeated reduplication of single chromatids; sections may appear to puff or swell due to differential gene activation; it is visible through the light microscope cyto >>> puff >>> lampbrush chromosome
polyteny >>> polytene chromosome
pomaceous fruit >>> pome
pome:
a fruit (e.g., apple, pear, quince) in which the seeds are protected by a tough carpel wall and the entire fruit is embedded in a fleshy receptacle bot
pomology: the science or study of growing fruit hort
population: a community of individuals, which share a common gene pool bot gene; in statistics, a hypothetical (often
infinitely large) series of potential observations among which observations actually made constitute a sample stat >>> Figure 38 >>> Table 35
population, closed:
a group of interbreeding plants (occurring in a certain area or in an experimental design) or a group of plants originating from one or more common ancestors, where there is no immigration of plants or pollen stat eco
population density: the number of individuals of a population per unit area of a particular habitat bot eco; in biotechnology, the cell
number per unit area or volume of a medium biot >>> plant density
population genetics:
the study of inherited variation in populations and its modulation in time and space; it relates the heritable changes in populations to the underlying individual processes of inheritance and development gene
population, Mendelian:
a group of (potentially) interbreeding plants (cross-fertilizing crops), which may occur in a certain area or in an experimental design gene stat
population size: the number of individuals in a population that are included in reproduction during a certain generation meth stat
population variance: a measure of dispersion defined as the average of the squared deviations between the observed values of the elements of a
population and the corresponding mean of those values stat
population waves:
irregular or rhythmic changes of the number of individuals in a population that are included in reproduction during certain generations meth stat
porosity: the proportion, as the percentage volume, of the total bulk volume of a body of rock or soil occupied by pore space agr
position (positional) effect: the change in the expression of a gene with respect to neighboring genes gene
positional cloning: a process of molecular cloning of a gene with reference to its position on the genetic or physical map biot
positive screening: a selection technique in which the best individuals in a genetically diverse population are preserved to become the parents,
either of the next screening generation, or of new >>> cultivar meth >>> negative screening
postemergence herbicide: a herbicide that affects the weeds after emergence phyt
postgamous incompatibility >>> crossbreeding barrier
postharvest loss(es):
crop losses due to parasites that occur after harvest, usually in the store; it can be reduced or prevented by ensuring that the stored product is dry, to prevent moulds developing, and that the product is in an airtight container that lacks oxygen, to prevent various animal pests from eating it agr phyt
poststratification: an estimation method that adjusts the sampling weights so that they sum to specified population totals corresponding to the
levels of a particular response variable stat
post-transcriptional gene silencing (PTGS):
silencing of an endogenous gene caused by the introduction of a homologous dsRNA, transgene or virus; in PTGS, the transcript of the silenced gene is synthesized but does not accumulate because it is rapidly degraded; this is a more general term than RNAi, since it can be triggered by several different means; it was initially considered a bizarre phenomenon limited to petunias and a few other plant species; in the 1990th, a surprising observation was made in petunias; while trying to deepen the purple color of these flowers, R. JORGENSEN introduced a pigment-producing gene under the control of a powerful promoter; instead of the expected deep purple color, many of the flowers appeared variegated or even white; the observed phenomenon was named "cosuppression", since the expression of both the introduced gene and the homologous endogenous gene was suppressed; meanwhile, it became one of the most important phenomenon in molecular biology; it has become clear that PTGS occurs in both plants and animals and has roles in viral defense and transposon silencing mechanisms; most exciting is the emerging use of PTGS and, in particular, RNA interference (RNAi) - PTGS initiated by the introduction of double-stranded RNA (dsRNA) - as a tool to knock out expression of specific genes biot meth
postzygotic incompatibility:
a condition where, in the case of incompatible or wide crosses, the zygote fails to develop, often for nutritional reasons; in some cases embryo culture can be used to rescue the embryo bot
potassium (K): an element that is required for plant growth; deficiency leads to reduced growth and to dark or blue-green coloration in the leaves chem phys
potassium iodide >>> chemical desiccation
pot-bound: used when a plant has an overly extensive root system in a too-small container hort
pot feet: supports placed under pots and planters to raise them off the ground for better drainage and air circulation hort
power (of statistical test): it is the probability that a statistical test will detect a defined pattern in data and declare the extent of
the pattern as showing statistical significance stat
PPA: Plant Patent Act; in 1930, the PPA was enacted into law in the United States; the plant patent grants the breeder the exclusive right, for 17
years, to propagate the patented plant by asexual reproduction; the purpose of the PPA was to encourage research investment in asexually reproduced plant species; since 1930, more than 6,000 plant patents have
been issued by the Patent and Trademark Office, primarily for fruit trees, flowers, ornamental trees, grape, and other horticultural species
ppm >>> parts per million
PPRP >>> plant pathogenesis-related proteins
preadaptation:
an adaptation evolved in one adaptive zone, which proves especially advantageous in an adjacent zone and so allows the organism to radiate into it; in breeding, the pretreatment of plants under moderate climatic (light, temperature, or nutrient) conditions in order to gradually accustom them to stress conditions phys evol
http://www.plantstress.com
prebasic seed:
an OECD class of pedigreed seed which is considered as equivalent to breeder seed and is used for the production of basic seed or foundation seed agr seed >>> breeder(‘s) seed
prebloom: the stage or period immediately preceding blooming agr
prebreeding:
all research and screening activities before a plant material enters the directed breeding process (e.g., the development of germplasm to a state where it is viable for breeder’s use); primarily, it involves the evaluation of traits from exotic material and their introduction into more cultivated backgrounds meth
prechilling:
the practice of exposing imbibed seeds to cool (+5 to +10°C) temperature conditions for a few days prior to germination at warmer conditions seed >>> stratification
precipitant: a substance or process that causes precipitation chem
precision: the difference between a sample-based estimate and its expected value; it is measured by the sampling error (or standard error) of an
estimate stat
precision farming:
a farming system which uses global positioning (GPS) technology involving satellites and sensors on the ground and intensive information management tools to understand variations in resource conditions within fields; the information is used to more precisely apply fertilizers and other inputs and to more accurately predict crop yields. Also see global positioning system agr
precision seed: calibrated or pelleted sorts of seeds used for precision drilling agr
precleaning: the process for removing the bulk of foreign materials grossly different in size from the harvested seed or other crop products seed
precocious embryo development: asexual development of the embryo before the flower opens and anthers dehisce bot
predecessor: within the crop rotation, the crop before the recent cropping agr
predisposition: an increase in susceptibility resulting from the influence of environment on the suspect phyt
preferential pairing: chromosome pairing in allopolyploids in which the most structurally similar chromosomes preferentially pair with another cyto >>> Ph locus
prefoliation >>> vernation
preharvest loss(es):
crop losses from parasites that occur in the field, as opposed to >>> postharvest losses that occur in the store agr phyt
preharvest sprouting >>> sprouting
premium wheats: wheat grades segregated on the basis of their specific quality characteristics to meet particular market requirements; these may
include high or low protein content, combined respectively with hardness or softness of the grain; there will generally also be the specification of certain varieties known to meet or exceed the quality
requirements agr
prepotency: the capacity of a parent to impress characteristics on its offspring so they are more alike than usual gene
preselection: selection of some individuals for further tests or studies meth
presoaking: presoaking of seeds in water has been suggested as a means to speed up germination meth
pretest: in order to determine performance prior to the organization or administration of a data collection activity stat
prevalence: the observed frequency of a trait or disease in a population, often at a particular age or time gene
prezygotic incompatibility:
in the case of incompatible or wide crosses the inhibition of pollen germination or the prevention of pollen tube growth, among other possible barriers of plant fertilization; in some cases the barrier can be overcome by in vitro pollination bot
pricking off: a method of transplanting tiny seedlings; the blade of a knife or plant marker is used to remove each plant from one spot and move
it to another meth hort
pricking out: a method of thinning seedlings by cutting them off at soil level so as not to disturb the roots of the other plants hort meth
pricking-out peg: an adjusted peg used for thinning or transplanting seedlings by cutting them off at soil level meth hort
prickle pollination >>> tripping mechanism
prickly: having thorns bot
primary constriction: the centromeric region of a chromosome cyto
primary culture: a culture resulting from cells, tissues, or organs taken from an organism biot
primary fluorescence: fluorescence originating from the specimen itself micr
primary gene pool:
it includes the cultivated species of a crop and related species from which useful genes can be most readily obtained for breeding; in general, it is the total sum of all the genetic variation in the breeding population of a species and closely related species that commonly interbreed with, or can be routinely crossed with, the species evol
primary host >>> host
primary infection: the first infection of a plant by the overwintering or oversummering pathogen phyt
primary inoculum: spores or fragments of a mycelium capable of initiating a disease phyt
primary leaf:
one of the first pair of leaves to emerge above the cotyledon during the development of a seedling; it is often morphologically distinct from subsequent leaves bot
primary sex ratio >>> sex ratio
primed in situ labeling: a technique that labels specific sequences in whole chromosomes by in situ DNA chain elongation or >>> PCR meth biot cyto
primer:
an oligonucleotide that forms a double strand by using a complementary segment; the primer is prolonged till the double strand is completed biot
priming:
the treatment of seeds with an osmotic solution (e.g., polyethylene glycol, which allows controlled hydration); the seed embryo develops to the point of germination and then is dried; it is applied for more uniform and rapid germination of certain vegetable seeds seed
primitive form:
in phylogeny, seedless vascular plants with underground rhizomes; they grow in tropical to subtropical areas and are terrestrial or epiphytic; in botany and breeding, as compared to cultivated crops, plants still show wild characteristics, such as brittle rachis, seed shattering, and others bot
primordium (primordia pl): the early cells that serve as the precursors of an organ to which they later give rise by mitotic development bot
principal host >>> host
PRISM:
an integrated software solution for plant researchers and agronomists; it provides user-friendly tools to manage experimental data; PRISM consists of several different book types, e.g., an experiment field book; each book type is used to classify information and to execute business rules; many of the book types are configured to produce a spreadsheet-like interface; it can create and print own reports and labels (including barcodes) meth stat
http://www.teamcssi.com/index.html
probability sample: a sample selected by a method such that each unit has a fixed and determined probability of selection stat
probe:
a radioactively or nonradioactively labeled and defined nucleic acid sequence that can be used in molecular hybridization; usually it is used for ex situ or in situ identification of specific, complementary nucleic acid sequences biot
processing of seeds: the complex of measures in order to clean, calibrate, disinfect, store, and pack seeds seed
prochromosome:
a heterochromatin block that is seen during the interphase of cell division and which is related to the number of chromosomes per complement or less cyto
procumbent: trailing or laying flat on the ground bot
proembryo: the young embryo in its early stages of development after zygote formation bot >>> direct embryogenesis
professional plant breeding:
there were no professional plant breeders before about 1900; >>> plant breeding was undertaken by farmers and amateurs
progenitor: the original, ancestral, or parental cell, individual, or species bot gene evol
progenitor cell: undifferentiated cell (i.e., immature cell) which will go on to develop into any cell type biot
progeny: offspring; plants grown from the seeds produced by parental plants bot gene >>> Figure 19
progeny selection: selection based on progeny performance meth >>> pedigree breeding
progeny test(ing): a test of the value of a genotype based on the performance of its offspring produced in some definite system of mating meth >>> pedigree breeding >>> Figure 19
prokaryote:
the class of organisms that does not have discrete cell nuclei in a nuclear envelope, including bacteria, but shows single, circular DNA molecules within the cytoplasm bio
prokaryotic >>> prokaryote
prolamin:
a protein; it is soluble in 70-90 % ethyl alcohol but not in water; it is found only in cereal seeds (e.g., gliadins in wheat and rye, zein in maize); upon hydrolysis they yield proline, glutamic acid, and ammonia chem phys >>> Table 15
proliferation: successive development of new parts, organs, etc. phys
proline
(Pro): a heterocyclic, nonpolar imino acid, which is present in all proteins; the major pathway for proline synthesis, which takes place in the cytoplasm, is from glutamate, through gamma-glutamyl phosphate and glutamyl-gamma-semialdehyde, a two-step reaction that is catalyzed by a single enzyme, D1-pyrroline-5-carboxylate synthetase chem phys >>> osmolyte
prometaphase: the stage in mitosis between the dissolution of the nuclear membrane and the organization of the chromosomes on the metaphase plate cyto
promiscuous: heterogeneous or haphazard mixture gene
promiscuous soybean: naturally-nodulating varieties of soybean that fix nitrogen with a wider range of native Rhizobia, and do not require
external inoculation agr
promoter:
a nucleotide sequence within an operon, lying between the operator and the structural gene or genes, that serves as a recognition site and point of attachment for the RNA polymerase; it is the starting point for transcription of the structural gene(s) in the operon, but is not itself transcribed; the promoter controls where (e.g., which portion of a plant) and when (e.g., which stage in the lifetime) the gene is expressed; for example, the promoter Bce4 is seed-specific gene biot >>> cauliflower mosaic virus (CaMV)
promoter sequence >>> promoter
propagate: to reproduce or cause to multiply or breed agr
propagating bench: a stationary, shallow box (sometimes covered by a glass pan or other means); it is usually filled with fine sand or certain
soil (often sterilized), which is kept moist; cuttings, slips, or shoots after in vitro culture are inserted into the growing medium until they form roots meth hort
propagating case >>> propagating bench
propagation: various methods by which plants are increased (e.g., seeds, division, separation, softwood cuttings, slips, grafting, budding, or
layering) meth hort agr
propagule: any type of plant to be used for reproduction (e.g., seedling, a rooted or unrooted cutting, a graft, a tissue-cultured plantlet, etc.) meth hort
proper block design:
a >>> block design is proper if all blocks have the same cardinality, i.e., contain the same number of plots; for binary designs, this just means that all blocks contain the same number of points stat
prophage:
the noninfectious form of a temperate bacteriophage in which the phage DNA has become incorporated into the lysogenic, host bacterial DNA biot
prophase: the first phase of mitosis and meiosis cyto
prophyll(um): the first leaf or protective scale of a lateral shoot bot
proplastid:
a colorless, double-membrane-bound organelle with little internal structure that acts as a precursor in the development of all plastids bot
protandry: the maturation of anthers before carpels (e.g., in sugarbeet, sunflower, or carrot) bot >>> Table 18
protease: an enzyme that catalyzes the hydrolysis of the peptide bonds of proteins and peptides chem phys >>> proteinase
protected variety:
a variety that is released and granted a certificate of plant variety protection under the legal statutes of a given country; the owner of a protected variety has the right of selling, offering, reproduction, import, export, or using for hybrid seed production seed
protein: a polymer that has a high relative molecular mass of amino acids; it has many functions in the living cell chem phys >>> Tables 15, 16, 33, 48
protein engineering: production of altered proteins by site-directed mutagenesis biot >>> biotechnology
proteinase: an enzyme that hydrolyzes protein molecules chem phys
proteome: the complete set of proteins detectable in a tissue phys
proteome analysis:
the basis of proteome analysis is an electrophoretic separation of the proteins on a two-dimensional protein gel, silver staining of proteins, followed by an image analysis of the stained gel; interesting protein spots identified on the gel can be excised; the critical protein can be extracted from the excised spot and further analysis of the protein (amino acid composition, partial amino acid sequence, isoelectric point, molecular weight) may result in protein identification meth phys biot
proteomics: systematic characterization of proteins, which are found in a tissue or in a specific physiological condition; the proteins can
be identified using mass spectroscopy
protoclonal variation: variability of somatic cells derived from protoplast culture biot
protoclone: a plant regenerated from a protoplast culture biot
protogyny: a condition in which the female parts develop first (e.g., in rapeseed) bot >>> Table 18
protoplasm:
a complex, translucent, colorless, colloidal substance within each cell, including the cell membrane, but excluding the large vacuoles, masses of secretions, ingested material, etc. gene
protoplast:
that part of a cell that is actively engaged in metabolic processes or a cell without a cell wall; protoplasts are produced by enzymes, which digest the wall; they are used for production of hybrid cells by protoplast fusion or for injection of foreign DNA bot biot
protoplast culture:
the isolation and culture of plant protoplasts by mechanical means or by enzymatic digestion of plant tissue, organs, or cultures derived from these; protoplasts are utilized for selection or hybridization at the cellular level and for a variety of other purposes biot
protoplast fusion:
a technique used in somatic hybridization experiments; it is used for overcoming crossing barriers; protoplasts are placed together and induced to fuse, applying fusogenic agents, such as polyethylene glycol or physical means; subsequent regeneration of the cell wall allows the propagation and regeneration of a somatic hybrid plant biot
prototroph:
a strain of organisms capable of growth on a defined minimal medium from which they can synthesize all of the more complex biological molecules they require, as opposed auxotroph phys
provenance: the geographical source and/or place of origin of a given lot of seed, propagules, or pollen fore
provenance test: an experiment, usually replicated, comparing trees grown from seed or cuttings that were collected from many geographical regions
of a species distribution fore
proximal: toward or nearer to the place of attachment cyto >>> centromere >>> chromosome arm
prune >>> pruning
pruning: trimming branches or parts of trees and shrubs in order to trim a plant or to bring the plant into a desired shape; in addition, the
removal of the growing point from a plant frequently causes the initiation of tillering or branching; the onset of flowering on the new vegetative growth may be delayed compared with that of unpruned plants; the
method may be also used for synchronization of flowering prior to hybridization; branches on trees strive in an upward direction; the internal struggle is all about reaching up for the light; the result can be
branches that are so intertwined that they themselves create shade for each other; that affects the formation of flower buds and, thereby, fruits; the best shape a fruit tree can have is one central trunk, with
branches that grow as close to a right angle as possible and that are at the most half as thick as the trunk; the tree is usually pruned to help it achieve this shape; however, once a branch is cut off, it does
not bear fruit; if the branch is cracked, it still hangs on and it will try and save the situation by forming more flowers and, thereby more fruits; e. g., in pear trees where the crack-method gave an up to 50 %
higher yield, but the method can also be used on apple, cherry and plum trees; the branch is cracked relatively close to the trunk; on plum trees, where the branches are more brittle, one can twist the branch
instead of snapping it, the cracking should be done in the early spring when the sap in tree is rising; the wound will heal quickly and there is no entry for fungal diseases; besides resulting in a greater
yield, the cracked branches also provide for more comfortable fruit-picking hort meth
pseudoallele: genes that behave as alleles in the allelism test but that can be separated by crossing-over gene
pseudoallelism >>> pseudoallele
pseudobivalent: a bivalent-like association of two mitotic chromosomes due to reciprocal chromatid exchange cyto
pseudocarp: a fruit consisting of one or more ripened ovules attached or fused to modified bracts or other nonfloral structures bot
pseudocereals: the grain amaranths, mainly quinoa (Chenopodium quinoa), and buckwheat (Fagopyrum spp.), are cereal-like grains that
are not of grass origin agr
pseudocompatibility:
the occurrence of fertilization that normally is prevented by incompatibility mechanisms; it is caused by specific environmental or genotypic conditions; for example, in rye, by high temperature (about +30°C) self-incompatibility can be broken so that seeds are set bot
pseudodominance: the apparent dominance of a recessive gene (allele), owing to a deletion of the corresponding gene in the homologous chromosome gene
pseudodominant >>> pseudodominance
pseudofertility >>> pseudocompatibility
pseudogamous heterosis: increased vigor of maternal offspring due to male parent influence on the endosperm bot gene
pseudogamy:
a type of apomixis in which the diploid egg cell develops into the embryo without fertilization of the egg cell, although only after fertilization of the polar nuclei with one of the sperm cells from the male gamete to form a normal triploid endosperm bot
pseudogene:
genes that have been switched off in evolution and no longer have any function; they are entirely neutral and evolve at a constant rate gene
pseudoheterosis:
luxuriance; it designates hybrids between species, varieties, or lines that exceed the parents in some traits, however, neither by sheltering deleterious genes nor by balanced gene combinations gene >>> heterosis
pseudoisochromosome: a chromosome that shows only equal ends as a result of interchanges cyto
pseudostem: a false stem; for example, bananas have pseudostems which look like tree trunks but are no; each banana stem consists of layers of
leaf sheaths, with the flower peduncle growing up through the centre and emerging at the centre of the crown bot
pseudovivipary: vegetative proliferation of plantlets in the inflorescence axes bot
Pto: a specific resistance gene in tomato, which controls resistance against the bacterium Pseudomonas syringae pv. tomato;
the gene encodes a cytosolic protein kinase; the Pto system remains the best characterised specific resistance gene system phyt
pubescent: covered with soft hairs, downy bot
pUC18 vector:
a plasmid cloning vector; size: 2.7 kb; about 100 copies per chromosome; it shows ampicillin resistance for selection and alpha complementing fragment of beta-galactosidase with in-frame polylinker for cloning biot
puff: a structural modified region of a polytene chromosome; it originates from the despiralization of deoxyribonucleoprotein cyto >>>
polytene chromosome >>> lampbrush chromosome
puffing >>> puff
pulp: the soft, succulent part of a fruit, usually composed of mesocarp and/or the pith of a stem bot
pulse: the edible seeds of any leguminous crop bot >>> legume(s)
pulsed-field gel electrophoresis: an electrophoretic technique in which the gel is subjected to electrical fields alternating between different
angles, allowing very large DNA fragments to move through the gel, and hence permitting efficient separation of mixtures of such large fragments meth biot
PUNNETT square: a diagrammatic representation of a particular cross used to predict the progeny of the cross; a grid is used as a graphic
representation of the progeny zygotes resulting from different gamete fusions in a specific cross meth
pure bred: derived from a line subjected to inbreeding gene
pure line: a number of individuals of a successive, self-pollinated crop, which derives from a single plant; a strain homozygous at all loci gene meth
pure line breeding >>> true breeding
pure-live seed: the percentage of the content of a seed lot that is pure and viable; it is determined by multiplying the percentage of pure seed
by the percentage of viable seed (germination percentage) and dividing by 100 seed
purity testing: determination of the degree of contamination of seed lots with genetically nonidentical, damaged, or pest-infected seeds seed
puroindoline protein(s): small, basic, cysteine-rich proteins found in bread wheat (Triticum aestivum); the wheat puroindoline
genes affect wheat milling and baking quality through their effects upon grain hardness; puroindoline a and b together comprise the wheat hardness locus and control whether wheat is soft or hard textured,
and they represent the grain hardness gene on chromosome 5DS; in hexaploid wheat, soft kernel texture is the wild type, whereas hard texture (hardness) results from any one of several mutations in the
puroindolines;mutations in either puroindoline result in hard texture; puroindoline a and b interact to create grain softness by binding cooperatively to starchgranules; by engineered introduction of
a puroindoline gene the hard textured grain of durum wheat (Triticum durum) and other cereals, including maize and barley, can be converted into soft texture (MORRIS and GEROUX, 2000) phys gene >>>
http://www.wsu.edu/~wwql/php/puroindoline.php
pustule: a blisterlike spot or spore mass developing below the epidermis, which usually breaks through at maturity phyt
P value: probability value; a decimal fraction showing, e.g., the number of times an event will occur in a given number of trials stat
PVPA >>> Plant Variety Protection Act
pycnidium (pycnidia pl): a flask-shaped fungal receptacle bearing asexual spores (i.e., pycniospores) bot
pycniospore: a spore from a pycnidium bot phyt
pycnotic: the concentration of the nucleus into a compact, strongly stained mass, taking place as the cell dies cyto
pyrenoid: it refers to a proteinaceous region of chloroplast, sometimes the site of accumulation of carbohydrate reserves bot phys
pyriform: pear-shaped bot
pyrimidine:
a basic, six-membered heterocyclic compound; the principal pyrimidines uracil, thymine, and cytosine are important constituents of nucleic acids chem phys
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