Glossary Plant Breeding

perhaps favoured in a dry flowering season (Mediterranean climates in spring)
because such flowers remain closed during much of the pollination period.
Cleistogamy inhibits desiccation of anthers and stigmas, thus promoting full seed set
by self-pollination. Flowers remain open only for a brief period, providing
opportunities for occasional outcrossing. In some grain legumes such as pigeonpea,
cleistogamy has been found under simple genetic control (monogenic recessive trait).
Clone. A group of individuals descended vegetatively (asexually) from a common
ancestor. Organisms so derived are highly uniform and homogeneous, and genetically
identical to their ancestor. A number of agricultural crops are clonally propagated.
Nearly all clonally propagated species are perennial outcrossers in nature, and all such
plants are highly heterozygous and conspicuously intolerant of inbreeding. They often
experience inbreeding depression following inbreeding (selfing). Only highly superior
clones that carry favourably interacting alleles of many different loci, much like the
genotypes of elite F 1 hybrids of corn, succeed in agriculture.
Cloning. Asexual production of a line of cells or organisms or segments of DNA
genetically identical to the original one.
C-meiosis. Also called colchicine meiosis. It is a modified meiosis that occurs following
the action of colchicine and other spindle poisons. If spindle formation is completely
suppressed during the first or the second or both meiotic divisions, meiotic products
with more than one chromosome set result. As a rule, spindle inhibition during the
first or second meiotic division yields two diploid meiotic products. If the spindle
cannot function in both meiotic divisions, the result is a tetraploid meiotic product.
Similarly in C-mitosis, complete spindle suppression leads to the formation of
restitution nuclei with doubled chromosome numbers.
Coadaptation. The selection processes that tend to accumulate harmoniously interacting
(coadapted) individuals or (coadapted) alleles into the gene pool of populations. Also
the selection processes that tend to favour individuals that have mutually beneficial
phenotypic associations with each other in populations.
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