Fig 4.

A conceptual model for the generation of apomixis in Boechera. The five genotypes that have led to the current patterns of apomixis are portrayed in the boxes. The text at the top of the boxes describes 1) the stable seed ploidy following a generation of self pollinating and 2) the female reproductive mode. The male and female symbols highlight the expected ploidy of pollen and embryo sacs respectively. Unreduced gametes have grey fill. Arrows connecting gametes to boxes indicate the contribution of that gamete for each formative mating. The four steps, which are described in the text, are highlighted (i–iv). For example, in step (iii), fertilization of a reduced ovule (from a line which only produces unreduced pollen) by reduced pollen (from the female apomeiosis-only individual) would produce a seed with a 2:3C embryo:endosperm ratio, but the genetic factors which cause the production of unreduced gametes are also transferred. Therefore, the offspring will produce seed with 2:6C ratio when the endosperm is self pollinated.