Backcross Breeding 2 - The Backcrossing Process Glossary

Backcross

A breeding method used to move one or a only a few desirable genes from an agronomically poor crop line to an elite line. This is done by crossing a donor parent to an elite line, and crossing offspring with the 'desired gene(s)' back to the elite parent.

backcross breeding

After a plant has been transformed, the event must be moved into an elite genetic background. This is done by mating the transformed plant back to elite plants over several generations.

Backcrossing

A breeding method used to move one or only a few desirable genes from an agronomically poor crop line to an elite line. This is done by crossing a donor parent to an elite line, and crossing offspring with the 'desired gene(s)' back to the elite parent.

BC1 Generation

(Backcross) 1 generation is the offspring resulting from the first cross back to the recurrent parent in the backcross breeding method.

Bt Gene

A gene originating from the Bacillus thuringiensis soil bacteria that encodes a protein toxic to the European corn borer.

chromosomes

The genetic structures in cells composed of condensed DNA ,which contain the genetic code for an organism.

cross

The deliberate mating of two parental types of organisms in genetic analysis.

crossing

The deliberate mating of two parental types of organisms in genetic analysis.

ELISA test

(Enzyme-Linked ImmunoSorbent Assay): A test which can be used to detect the presence of proteins encoded by the transgene in a genetically engineered crop plant.

elite

A crop line that has many genes for good agronomic traits that result in high yields in a particular environment.

event

The insertion of a particular transgene into a specific location on a chromosome. Events are differentiated by two factors: 1) what transgene was inserted, and 2) where on the chromosome it inserted and how many gene copies inserted at that locus.

F1 Generation

(first filial generation) The offspring produced from crossing two parental lines or individuals.

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.

genetic fingerprinting

Determining the genetic makeup of an organism with the use of DNA markers.

genotypes

The allelic composition of cells or organisms.

herbicide

A pesticide used to kill plants.

herbicide resistance

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.

heterozygous

An organism that has two different alleles at one or more locations on a chromosome.

homozygous

An organism that has two identical alleles at one or more locations on a chromosome. Inbred lines are homozygous at many of their gene loci.

hybrid

An individual produced by crossing two parents of different genotypes.

hybrids

Individuals produced by crossing two parents of different genotypes.

inbred

An organism that has been self-fertilized for several generations until it is homozygous at all important gene loci, "genetically pure."

line

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.

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.

marker

An easy to detect trait controlled by a known gene. Markers, such as antibiotic or herbicide resistance, are often used to determine if an organism is transgenic.

metabolism

Chemical reactions in the cell, often regulated by proteins made in that cell, that are critical to maintain he life of the cell or differentiate the cell.

PCR

(polymerase chain reaction) A method for replicating a particular sequence of DNA in vitro. Used to generate greater amounts of DNA for analysis or to determine if a particular sequence exists.

phenotype

The observable physical characteristics of an organism that are determined by a combination of the genetic composition (genotype) and the environment of the individual.

progeny

The offspring of an organism.

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.

protein synthesis

The production of proteins in a cell. Proteins are chains of amino acids linked in the order determined by the genetic code.

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.

roundup

A herbicide that provides non-selective control of several annual and perennial weeds. Roundup will also damage crops, such as corn and soybeans that are not Roundup-resistant.

Roundup-Ready

A trade name given to certain varieties of corn or soybean which are resistant to the herbicide, Roundup, whose active ingredient is glyphosate.

selection

A natural or artificial process that favors or induces survival and perpetuation of one kind of organism over others that die or fail to produce offspring.

species

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

tissue culture

Plant cells are grown in culture which allows them to be manipulated and then induced to develop into whole plants.

trait

The characteristic that results from an expressing gene(s). Ex. Upright leaves, drought tolerance, Bt resistance. A trait can be influenced by the environment.

transformation

A process by which extra genetic material is inserted into the cells of an individual.

transgene

A gene that has been genetically altered. They are usually used to transform organisms.

transgenic

An organism that has a new genetically engineered DNA sequence found in every one of its cells. Genetically engineered organisms are transgenic. These two terms are used interchangeably.

transgenic plant

A plant that has a new genetically engineered DNA sequence present in every one of its cells. Genetically engineered plants are transgenic plants. These two terms are used interchangeably.

variety

Crop plants within a species that have the same genetic composition. Because plants in a variety are usually heterozygous, their offspring will not remain genetically pure (i.e., corn hybrid varieties).

yield drag

A negative effect on grain yield associated with crop plants that have a specific gene or a specific trait.

yield lag

A relative reduction in yield observed in some hybrids or varieties compared with the yield observed in the most recently produced hybrids or varieties.

yield potential

The highest yield a plant (hybrid, variety, etc.) is capable of producing when grown in ideal conditions.