Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in XXXX ovules.

@entity8597 @entity1101 @entity458
BACKGROUND: Genetically unreduced (2n) @entity8597 ( @entity8597 ) form in ovules of gametophytic apomicts, the 2n eggs of which develop into embryos parthenogenetically. In many apomicts, 2n @entity8597 form precociously during ovule development. Whether meiosis and @entity458 also occur precociously in facultative apomicts (capable of apomictic and sexual reproduction) has not been studied. We determined onset timing of meiosis and @entity458 for 569 @entity1101 genotypes, many of which produced 2n @entity8597 facultatively. RESULTS: Genotype differences for onset timing of meiosis and @entity458 , relative to ovule development, were highly significant. A major source of variation in timing of sexual germline development was presence or absence of apomictic @entity8597 , which formed from nucellar cells (apospory) in some genotypes. Genotypes that produced these aposporous @entity8597 underwent meiosis and @entity458 precociously. Aposporous @entity8597 formation was most prevalent in subsp. verticilliflorum and in breeding lines of subsp. bicolor. It was uncommon in land races. CONCLUSIONS: The present study adds meiosis and @entity458 to floral induction, apomictic @entity8597 formation, and parthenogenesis as processes observed to occur precociously in apomictic plants. The temporally diverse nature of these events suggests that an epigenetic memory of the plants' apomixis status exists throughout its life cycle, which triggers, during multiple life cycle phases, temporally distinct processes that accelerate reproduction.
