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. 2019 May 31;10:724. doi: 10.3389/fpls.2019.00724

FIGURE 5.

FIGURE 5

Timing of sexual program termination may determine apomixis type in Boechera. In Antennaria-type diplospory, the sexual program aborts early, meiosis fails completely, and the gametophyte (ES) forms directly from the megaspore mother cell (MMC). In Taraxacum-type diplospory, the sexual program aborts during meiotic prophase I. Restitution of the first meiotic division (the reductional division) then occurs, two unreduced spores form, and the ES generally forms from the chalazal most spore. In Hieracium-type apospory, sexual reproduction can be terminated as early as early meiosis or as late as early ES formation, with unreduced ESs forming adventitiously from sporogenous nucellar cells.