Free from specified viruses based on tests designed to detect the presence of the organisms in question.

Plants derived from any form of cell culture involving the use of somatic plant cells.

The process by which a cell monolayer or a plant explant is transferred, without subdivision, into fresh medium. (See also Passage)

A type of culture in which cells, or aggregates of cells, multiply while suspended in liquid medium.

A substrain can be derived from a strain by isolation a single cell or groups of cells having properties or markers not shared by all cells of the parent strain.

A cell possessing two or more genetically identical nuclei in a common cytoplasm, derived as a result of cell-to-cell fusion.

Plants regenerated from cell cultures derived from meiospores, gametes or gametophytes.

Variation in phenotype, either genetic or epigenetic in origin, expressed by gametoclones.

A culture which is capable of only a limited number of population doubling after which the culture ceases proliferation. (See In vitro senescence)

Phenotypic variability which has a nongenetic basis.