rest periodA physiological condition of viable seed s, buds or bulbs that prevents growth even in the presence of otherwise favourable environmental conditions.
restitution nucleusA single nucleus arising from a failure of nuclear division, either during meiosis, in which a gamete is formed with the unreduced chromosome number; or…
restriction endonucleaseA class of enzymes that cut DNA after recognizing a specific sequence. The three types of restriction endonuclease are: I.
Restriction endonuclease (enzyme)A class of endonucleases that cleaves DNA after recognizing a specific sequence, such as BamH1 (GGATCC), EcoRI (GAATTC), and HindIII (AAGCTT). Type I.
restriction exonucleaseA class of enzymes that degrade DNA or RNA, starting from either the 5'- or the 3'-end.
restriction fragmentA shortened DNA molecule generated by the cleavage of a larger molecule by one or more restriction endonucleases.
restriction fragment length polymorphism(Abbreviation: RFLP). A class of genetic marker based on the detection of variation in the length of restriction fragments generated when DNA is treated…
Restriction fragment length polymorphism (RFLP)Differences in nucleotide sequence between alleles at a chromosomal locus result in restriction fragments of varying lengths detected by Southern analysis.
retro-elementAny of the integrated retrovirus es or the transposable elements that resemble them.
retroposonA transposable element that moves via reverse transcription but lacks the long terminal repeat sequences necessary for autonomous transposition.
retroviral vectorsGene transfer systems based on viruses that have RNA as their genetic material.
retrovirus(REH-troh-VY-rus) A type of virus that has RNA instead of DNA as its genetic material.
reversal transferTransfer of a culture from a callus-supporting medium to a shoot-inducing medium.
Reverse geneticsUsing linkage analysis and polymorphic markers to isolate a disease gene in the absence of a known metabolic defect, then using the DNA sequence of the…
Reverse transcriptaseAn enzyme that uses an RNA molecule as a template for the synthesis of a complementary DNA strand. Synonym: RNA -dependent DNA polymerase.
reverse transcription(ree-VERS tran-SKRIP-shun) In biology, the process in cells by which an enzyme makes a copy of DNA from RNA.
reversionRestitution of a mutant gene to the wild-type condition, or at least to a form that gives the wild-type phenotype; more generally, the appearance of a…
rhizobacteriumA micro-organism whose natural habitat is near, on, or in, plant roots.
RhizobiaBacteria in a symbiotic relationship with leguminous plants that results in nitrogen fixation. See Nitrogen fixation.
Rhizobium(pl.: Rhizobia) Prokaryotic species which are able to establish a symbiotic relationship with leguminous plants, as a result of which elemental nitrogen…
RhizosphereThe soils region on and around plant roots.
Ri plasmidA class of large conjugative plasmid s found in the soil bacterium Agrobacterium rhizogenes , which can infect certain plants and cause hairy root disease.
RiboseA monosaccharide found in all ribonucleosides, ribonucleotides and RNA. Its close analogue, 2-deoxyribose, is similarly found in all deoxyribonucleosides…
ribosomal binding siteA sequence of nucleotides near the 5' end of a bacterial mRNA molecule that facilitates the binding of the mRNA to the small ribosomal sub-unit.
ribosomal DNAThe coding locus for ribosomal RNA. This is generally a large and complex locus, typically composed of a large number of repeat units, separated from one…
ribosomal RNA(Abbreviation: rRNA). The RNA molecules that are essential structural and functional components of ribosomes, where protein synthesis occurs.
ribuloseA keto-pentose sugar (C5H11O5) involved in the carbon dioxide fixation pathway of photosynthesis.
ribulose biphosphate(Abbreviation: RuBP). A five-carbon sugar combined with carbon dioxide to form a six-carbon intermediate in the first stage of the dark reaction of…
rinderpestCattle plague; a viral infection of cattle, sheep and goats.
RIPThe procedures used to unbundle email collections into individual emails during the e-discovery process while preserving authenticity and ownership.
RiskThe possibility of loss; the uncertainty of future returns.
risk analysisA process consisting of three components: risk assessment, risk management and risk communication performed to understand the nature of unwanted, negative…
risk assessmenta scientifically based process consisting of the following steps: i) hazard identification; ii) hazard characterization; iii) exposure assessment; and iv)…
risk communicationThe interactive exchange of information and opinions throughout the risk analysis process concerning hazards and risks, risk-related factors and risk…
risk managementThe process, distinct from risk assessment, of weighing policy alternatives, in consultation with all interested parties, considering risk assessment and…
RNAOne of the two types of nucleic acids found in all cells. In the cell, RNA is made from DNA (the other type of nucleic acid), and proteins are made from…
RNA (Ribonucleic acid)An organic acid composed of re- peating nucleotide units of adenine, guanine, cytosine, and uracil, whose ribose components are linked by phosphodiester…
RNA editingPost-transcriptional processes that alter the information encoded in RNA s.
RNA polymeraseTranscribes RNA from a DNA template. (See Polymerase, RNA.)
rolgenes A family of genes, present on the Ri plasmid of Agrobacterium rhizogenes, that when transferred to a plant upon infection by the bacterium, induce…
rootTo trap a target in place/stuck using a "root" type spell such as Entangling Roots.
root apexThe apical meristem of a root; very similar to the shoot apical meristem in that it forms the three meristematic areas: the protoderm (develops into the…
root capA mass of reinforced cells covering and protecting the apical meristem of a root.
root cultureThe culture of isolated apical or lateral root tips to produce in vitro root systems with indeterminate growth habits.
root cuttingCutting made from sections of roots alone.
root hairsOutgrowths from epidermal cell walls of the root, specialized for water and nutrient absorption.
root noduleA small round mass of cells attached to the roots of leguminous plants, containing symbiotic nitrogen-fixing bacteroids, particularly Rhizobium spp.
root tuberThickened root that stores carbohydrates.
Root zoneThe volume of soil or growing medium containing the roots of a plant. In soil science, the depth of the soil profile in which roots are normally found.
rootstockThe trunk or root material to which buds or scions are inserted in grafting. See: stock.
rotary shakerRotating apparatus with a platform on which liquid media or cultures can be continuously shaken.
Roundup-readyäDescribing transgenic crop varieties that carry the bacterial gene which detoxifies the herbicide glyphosate, thereby making them resistant to its…
ruminantAnimal having a rumen - a large digestive sac in which fibrous plant material is fermented by commensal microbes, prior to its digestion in a "true"…
RunnerTypically said "runner-runner" to describe a hand that was made only by catching the correct cards on both the turn and the river.
rustA generic descriptor for various serious fungal plant pathogens, which infect the leaves and stems of crops.
S phaseThe phase in the cell cycle during which DNA synthesis occurs.
S1 mappingA method to characterise post-transcriptional modifications in RNA (removal of introns etc.
S1 nucleaseAn enzyme obtained from the filamentous fungus Aspergillus oryzae which specifically degrades RNA or single-stranded DNA into its constituent…
saccharifactionFollowing liquefaction, the hydrolysis of polysaccharides by glucoamylase to maltose and glucose.
SalmonellaA genus of rod-shaped, gram-negative bacteria that are a common cause of food poisoning.
salt toleranceThe ability of a plant in soil or in culture to withstand a concentration of common salt (sodium chloride) which is damaging or lethal to most other…
SAPFluid content of the xylem and phloem cells of plants. Fluid content of the vacuole generally referred to as cell sap.
saprophyteAn organism (generally a fungus) that depends on dead plant or animal tissue for its source of nutrition and metabolic energy.
satellite DNAHighly repetitive DNA in plant and animal genomes, consisting of millions of copies of sequences typically in the range 5-500 bp long.
satellite RNAA small, self-splicing RNA molecule that accompanies several plant viruses, including tobacco ringspot virus. Synonym: viroid.
Satellite RNA (viroids)A small, self-splicing RNA molecule that accompanies several plant viruses, including tobacco ringspot virus.
ScaffoldThe central protein aceous core structure of condensed eukaryotic chromosomes. The scaffold is composed of non-histone chromosomal protein s.
Scale UpConversion of a process, such as fermentation of a micro-organism, from a small laboratory scale to a larger industrial scale.
scanning electron microscope(Abbreviation: SEM). An electron-beam-based microscope used to examine, in a three dimensional screen image, the surface structure of prepared specimens.
SCARAbbreviation for sequence characterized amplified region.
scarificationThe chemical or physical treatment given to certain seed s having hard, impermeable seed coats in order to puncture or weaken the seed coat sufficiently…