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dc.contributor.authorLora, Jorge-
dc.contributor.authorHormaza Urroz, José Ignacio-
dc.contributor.authorHerrero Romero, María-
dc.identifier.citationLora J, Hormaza JI, Herrero M. The progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae). Annals of Botany 105 (2): 221-231 (2010)en_US
dc.description33 Pag. The definitive version, with the figures, is available at: http://aob.oxfordjournals.org/en_US
dc.description.abstractBackground and Aims: Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates. Methods: The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically. Key Results: A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development. Conclusions: A plesiomorphic simple gynoecium hosts a simple pollen–pistil interaction, based on a support–control system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigma–style interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.en_US
dc.description.sponsorshipThis work was supported by the Spanish Ministry of Education (Project Grants AGL2004-02290/AGR, AGL2006-13529 and AGL2007-60130/AGR), GIC-Aragón 43, Junta de Andalucía (AGR2742), and the European Union under the INCO-DEV program (Contract 015100). J.L. was supported by a grant from Junta de Andalucía.en_US
dc.format.extent141035 bytes-
dc.publisherOxford University Pressen_US
dc.subjectAnnona cherimolaen_US
dc.subjectembryo sacen_US
dc.subjectpollen–pistil interactionen_US
dc.subjectpollen tubeen_US
dc.titleThe progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae)en_US
dc.description.peerreviewedPeer revieweden_US
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