Glossary Plant Breeding

Somatic Mutation. A mutation in a somatic or body cell.
Somatic Embryo. The embryo of somatic origin. It differs from zygotic one in lacking a
well-defined hypocotyl. It also does not experience desiccation and dormancy; these
properties seem to be imposed by accumulation of abscisic acid that, in turn, is
presumably provided by the maternal tissues (in the zygotic embryo).
Somatic Embryogenesis. The genesis of embryos from somatic cells through tissue
culture technology. Such embryos are desiccated and encapsulated to form artificial or
somatic seeds.
Somatic Seed. A somatic embryo derived through tissue culture and encapsulated in a
suitable matrix (gel) with nutrients, growth regulators, and antibiotics necessary for
the development of a complete plant. It is also called synthetic or artificial seed. It can
be stored for several years and can be sown like natural ones.
Somatic Segregation. The segregation at mitosis of genes giving rise to variegation or
sectoring.
Somatoplastic Sterility. A condition of embryo abortion following self-fertilization due
to disturbances in embryo-endosperm relationship (e.g., alfalfa). This condition
obviously favours heterozygosity.
Sorts. The different botanical forms of a species.
SOS Repair. Save our Soul Repair; a process or mechanism of repairing damage to
DNA. It is an error-prone process whereby gross structural DNA damage is
circumvented by allowing replication to proceed past the damage through imprecise
polymerisation. A biological system resorts to this mechanism of DNA repair when
all other such systems fail. As it is an error-prone and imprecise mechanism,
phenotypic expression of repaired DNA may be altered.
Southern Blot. Transfer of electrophoretically separated fragments of DNA from a gel to
an absorbent sheet such as paper. This sheet is then immersed in a solution containing
a labelled probe that will bind to a fragment of interest.
Spacer. The nucleotide sequence of DNA found between genes (compare it with introns
or intervening sequences, which are present within a eukaryotic gene). It may be
transcribed, but is never translated. Its function is still unknown.
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