Glossary Plant Breeding

Chromosome Complement. The group of chromosomes derived from a particular
gametic or zygotic nucleus. It may be composed of one (monoploid nucleus), two
(diploid nucleus), or more (polyploid nucleus) chromosome sets.
Chromosome Disjunction. The separation of paired chromosomes during anaphase of
first meiotic division.
Chromosome Loss. Failure of a chromosome to become part of the daughter nucleus at
cell division. Slow replication of DNA of the chromosome (compared to the rest
ones), its slow movement towards the pole, and similar other reasons may cause
chromosome loss during the cell multiplication.
Chromosome Map. The graphic representation of a chromosome in which the genes
belonging to a particular linkage group are plotted according to their relative
distances. In genetic maps, recombination frequency expressed in map units is used as
a measure of distance between linked genes. However, in cytological maps, genes are
located on the basis of cytological findings obtained with the aid of chromosome
mutations such as deletions, inversions, or translocations.
Chromosome Rearrangement. See chromosome aberration.
Chromosome Substitution. The process by which a chromosome of one variety is
replaced or substituted into the genome of another variety. If a non-homologous
chromosome is substituted into the genome of another species, the process is referred
to as alien chromosome substitution. Nullisomics and monosomics can be used to
facilitate such substitutions.
Chromosome Theory of Inheritance (Sutton and Boveri, 1902). The unifying theory
stating that chromosomes are containing structures of genetic factors. This theory
accounts for inheritance pattern of Mendelian traits.
Chromosomal Hybrid Sterility. Sterility associated with the failure of chromosome
pairing and other meiotic misadventures indicating lack of structural homology
between chromosomes of two parental species. All these upset formation of
functional gametes.
cis Dominance. The ability of a gene to affect genes next to it on the same chromosome.
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