Inhibitors of Fatty Acid Synthesis and Elongation Glossary

ACCase

acetyl-Coenzyme A carboxylase; enzyme responsible for production of fatty acids and is the target of many herbicides that have the lipid synthesis inhibitor mode of action.

alleles

One of the different forms of a gene that can exist at a single locus. A single allele for each locus is inherited separately from each parent.

amino acid

The basic building blocks of proteins. The sequence of amino acids in a protein and protein function are determined by the genetic code.

annual

Living or growing for only one year or season.

apoplast

Regions or cells in the plant not bound by a membrane (i.e. the cell wall region between cells or xylem tissue; apoplastic means 'non-living' tissue. 

base

A chemical compound that accepts a proton.

catalyzes

Speeds up.

chloroplast

An organelle within the plant cell in which the photosynthetic reactions are compartmentalized. The thylakoid membranes within the chloroplast are the site of the photosynthetic pigments and electron transfer components used to make energy from photosynthesis. The non-membrane space within the chloroplast is called the stroma; this is where photosynthetic energy is used to convert CO2 into sugars.

CoA

An abbreviation for coenzyme A; a molecule with an active thiol group that functions as an acyl or acetyl group carrier in several biochemical reactions.

conjugation

Attachment of a molecule (herbicide) to another molecule like sugar, lipid, lingnin, cellulose, which inactivates the original molecule.

cutin

A waxy transparent material in the cuticle of plants that contains highly polymerized esters of fatty acids.

cyclohexanediones

Family of herbicides that belong to the lipid synthesis inhibitor mode of action (dims).

cytochrome P450

A large family of mixed-function monooxygenases used for Phase I metabolism of xenobiotics in almost all eukaryotes.

cytosol

The liquid substance of protoplasm, excluding all the organelles such as nuclei, plastids, ribosomes.

degradation

The breakdown of a chemical by either chemical or physical reactions that make it inactive.

detoxify

To deactivate a herbicide into nontoxic compounds through metabolic reactions.

dicots

A subclass of of Angiosperms.

They tend to have:
-broad leaves
-two cotyledons
-netlike veins in the leaves
-flower parts are usually in fours or fives
-a ring of primary vascular bundles in the stem
-taproot system

ex. most trees and shrubs, broadleafs

domain

A discrete portion of a protein with its own function. The combination of domains in a single protein determines its overall function.

endogenous

Found naturally in an organism.

Endosymbiont Theory

The theory that eukaryotic cells evolved from large prokaryotic cells that engulfed free-living bacteria; mitochondria evolved from aerobic bacteria and chloroplasts evolved from photosynthetic bacteria.

environment

The combinations of all the conditions external to the genome that potentially affect gene expression.

enzyme

A protein that catalyzes, or speeds up, a specific biochemical reaction without changing the nature of the reaction.

fatty acids

A class of compounds containing a long hydrocarbon chain and a terminal carboxyl group. Fatty acids can be saturated (containing no carbon-carbon double bond), monounsaturated (containing one carbon-carbon double bond), or polyunsaturated (containing multiple carbon-carbon double bonds).

frequency

A measure of the number of times per second (units of sec-1) that the electric field in a photon vibrates.

gene

The fundamental unit of heredity that carries genetic information from one generation to the next. A gene is an ordered sequence of nucleotides located on a particular position on a particular chromosome that encodes a specific functional protein.

genes

The fundamental unit of heredity that carries genetic information from one generation to the next. A gene is an ordered sequence of nucleotides located on a particular position on a particular chromosome that encodes a specific functional protein.

germination

Process in which seeds or spores sprout and begin to grow.

glutathione

A tripeptide made from glutamic acid, cysteine, and glycine used as the major anti-oxidant molecule in cells for binding and detoxifying many xenobiotics.

glutathione transferase

An enzyme that catalyzes the binding of xenobiotics to glutathione.

glycerolipids

The family of lipids containing a glycerol backbone.

half-life

The time it takes for a compound to degrade to half of its original concentration.

herbicide

A pesticide used to kill plants.

herbicide safeners

Chemicals that protect crops from injury by herbicides, but do not prevent the herbicide from killing weeds.

hydrolysis

The reaction of a substance with water.

leaching

The removal of soluble materials from one zone in soil to another via water movement in the profile. (Soil Science Society of America. 1997, p. 62).

ligase

An enzyme that can rejoin cut strand of DNA.

lines

Plants within a species that have the same genetic composition and are genetically pure, (i.e., inbred line). Lines are typically not agronomically competitive and are used only in plant breeding.

loss-of-function mutants

Biotypes that have lost the ability to carry out a particular enzymatic reaction.

mechanism of action

The specific process inhibited by a herbicide.

metabolism

A general term referring to the change of a herbicide from an active to an inactive state.

microbes

microscopic organisms such as bacteria and fungi

pathway

A sequence of interconnecting enzyme reactions.

perennial

A plant that lives three or more years.

phosphatidylcholine

A major lipid component of cell membranes containing equal amounts of saturated and monounsaturated fatty acids, phosphate, and choline; also called lecithin.

phytotoxic

A substance which is toxic to plants.

plastids

Pigmented cytoplasmic organelles found in plant cells and other organisms; includes chloroplasts and mitochondria.

pro-herbicides

Herbicides that are not physiologically active as the parent compound, but must be metabolically activated in order to become toxic.

protein

A large molecule composed of one or more chains of amino acids in a specific order. Proteins are necessary for the structure, function, and regulation of an organism's cells, tissues, and organs. Each protein has a unique function determined by its shape.

recessive

A trait that will not be expressed unless there are two copies of the gene allele present in an organism.

relative fitness

The fitness of one genotype when compared with another.

resistance

The ability of an organism to survive and thrive in the presence of something that would normally cause damage or death, i.e., herbicide-resistant corn, Roundup-ready corn.

resistant

The inherited ability of a plant to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type. In a plant, resistance may be naturally occurring or induced by such techniques as genetic engineering or selection of variants produced by tissue culture or mutagenesis.

safener

A compound used in conjunction with a herbicide to provide extra protection to the crop without reducing weed control.

seed

Ripened fertilized ovule of a flowering plant that contains an embryo and normally capable of germination.

seedling

A young plant that is grown from a seed.

selection pressure

The process that changes the relative frequency of one or more genes within a population.

selective

A herbicide that is toxic to certain plants but harmless to others.

selectivity

Differential effect of a herbicide when applied to a mixed population of plants; sensitive plants die, tolerant plants are unharmed. Implies that different plant species do not respond in the same way to a particular herbicide. Herbicides which cause one species of plants to die, but not another, are selective. Selectivity allows for acceptable weed control without injury to crop plants.

shoots

Portion of the developing seedling above the root system.

soil

The top layer of the Earth’s surface, consisting of four major components: air, water, organic matter and mineral matter. There are three categories of soil particles--sand, silt and clay--which are called "soil separates."

solubility

The ability of a solute to dissolve in a solvent; the ability of a herbicide to dissolve in water.

species

A fundamental category of taxonomic classification, ranking below a genus or subgenus and consisting of related organisms capable of interbreeding.

Structure

The combination or arrangement of soil particles that forms peds or aggregates.

suberin

A long chain waxy material found in plant cell walls, the endodermis (the Casparian strip), and the cuticle.

sulfoxidase enzymes

Oxidoreductases that incorporate molecular oxygen into substrates.

susceptible

The inability to survive a herbicide at its use rate.

time

One of the conventionally accepted soil forming factors.

tolerance

The inherent ability of a species to survive and reproduce after herbicide treatment; this implies that there was no selection or genetic manipulation to make the plant tolerant; it is naturally tolerant.

vapor

A substance in the gaseous state.