tailieunhanh - báo cáo khoa học: " Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules | Carman et al. BMC Plant Biology 2011 11 9 http 1471-2229 11 9 BMC Plant Biology RESEARCH ARTICLE Open Access Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules 1 2 2 3 2 2 4 John G Carman Michelle Jamison Estella Elliott Krishna K Dwivedi Tamara N Naumova Abstract Background Genetically unreduced 2n embryo sacs ES form in ovules of gametophytic apomicts the 2n eggs of which develop into embryos parthenogenetically. In many apomicts 2n ES form precociously during ovule development. Whether meiosis and sexual ES formation also occur precociously in facultative apomicts capable of apomictic and sexual reproduction has not been studied. We determined onset timing of meiosis and sexual ES formation for 569 Sorghum bicolor genotypes many of which produced 2n ES facultatively. Results Genotype differences for onset timing of meiosis and sexual ES formation relative to ovule development were highly significant. A major source of variation in timing of sexual germline development was presence or absence of apomictic ES which formed from nucellar cells apospory in some genotypes. Genotypes that produced these aposporous ES underwent meiosis and sexual ES formation precociously. Aposporous ES 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 sexual ES formation to floral induction apomictic ES 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. Background For angiosperms apomixis means asexual reproduction by seed 1 . It is strongly associated with hybridity and polyploidy and molecular .