Apomixis

Apomixis is seed formation without the usual sexual process of meiosis and fertilization. Its pathways produce embryos from unreduced egg cells or other maternal tissues.

Diplospory: Apomixis in which an unreduced embryo sac develops from a megaspore mother cell without normal meiosis. This pathway bypasses meiosis while retaining the embryo sac’s usual cellular origin.
Ovule: The plant structure containing the female reproductive cells that develops into a seed after fertilization. Apomictic embryos and embryo sacs arise within this seed-forming structure.
Hybrid seed: Seed produced by crossing genetically distinct parent lines to obtain offspring with desired traits. Apomixis could preserve hybrid traits across generations without repeating the parental cross.
Dandelion: A flowering plant genus whose familiar species include many apomictic lineages. Dandelions provide well-studied examples of seed production without ordinary sexual reproduction.
Apospory: Apomixis in which an unreduced embryo sac develops from a somatic cell of the ovule. This pathway forms the embryo sac from maternal tissue rather than a meiotic product.
Embryo sac: The female gametophyte of flowering plants, typically containing an egg cell and central cell. Apomixis often changes how this structure forms or how its egg develops.
Heterosis: The increased vigor or performance of hybrid offspring relative to their parents. Fixing heterosis in seed is a major proposed benefit of transferring apomixis into crops.
Hieracium: A large genus of flowering plants that includes species with aposporous apomixis. Research on hawkweeds helped establish the cellular pathways of apomixis.
Parthenogenesis: Development of an embryo from an unfertilized egg cell. In many apomictic pathways, the embryo begins when an unreduced egg develops without fertilization.
Megaspore mother cell: A diploid cell in the ovule that normally undergoes meiosis to produce megaspores. Diplospory alters the usual meiotic fate of this cell.

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