Glossary Plant Breeding

Coarse Cereals. A group of cereals consisting of maize, sorghum, pearl millet, ragi,
barley and a host of small millets including proso and foxtail. These are nutritionally
rich cereals.
Code Dictionary. A listing of 64 possible codons and their translational meanings such
as corresponding amino acid(s), chain termination, and the like.
Codominance. The situation in which a heterozygote shows the phenotypic effects of
both alleles equally.
Codon. A triplet of bases of mRNA that encodes a single amino acid or specifies
commencement or termination of translation of a genetic message.
Coefficient of Coincidence. The ratio of the observed number of double recombinants to
the expected number. It is a measure of the intensity of interference. Its value ranges
from 0 (absolute interference, that is, no double recombinants) to more than 1
(negative interference).
Coefficient of Selection. See selection coefficient.
Coenospecies. Two or more taxonomic species with the common evolutionary origin.
Only limited gene exchange can occur between coenospecies. Usually sterile hybrids
are produced by hybridisation.
Coenzyme. Usually a non-protein compound of low molecular weight required for the
action of some enzymes. For example, dehydrogenases require a nicotinamideadenine
dinucleotide (NAD + ) to function. In many coenzymes, as in NAD + , the
essential components are vitamins, particularly those of the B group.
Cofactor. A metal or a prosthetic group (in case of conjugated proteins) required by the
enzymes for their activity.
Coincidence. See coefficient of coincidence.
Colcemid. A synthetic equivalent of colchicine. It is used to induce polyploids usually in
animals.
Colchicine (Blakeslee and Avery 1937). An alkaloid drug used to induce polyploidy in
plant species. However, at a lower concentration, it also acts as a mutagen. It is
extracted from seeds or corms of the autumn crocus (Cochicum autumnale L.), a
member of family Liliaceae. It acts as spindle poison and thus arrests formation of
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