caa a22 4500 477038603 CHVBK 20180405111311.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00985815 doi (NATIONALLICENCE)springer-10.1007/BF00985815 Ultrastructural features of megasporogenesis in Torreya nucifera ( Taxaceae ) [Elektronische Daten] [A. Fiordi, M. Lippi, S. Marini, G. Tani] In megasporogenesis ofTorreya nucifera (Taxaceae) more than one product of meiosis can start to germinate, a process previously observed inTaxus. Ultrastructural analysis ofT. nucifera revealed that this behaviour is cytologically determined by the presence of a transfer cell type wall-membrane apparatus and by the presence of uncommonly complex plasmalemmasomes in the megasporocyte. These features may determine a uniform supply of nutrients to the entire megasporocyte cytoplasm, so that after meiosis the germination potential is not restricted to the chalazal megaspore. Even if more than one product of meiosis can originate the female gametophyte in bothTaxus andTorreya, this process involves different ultrastructural aspects in the two species. In conclusion, the extension of the germination potential is a common characteristic to both species but it is most probably the result of some evolutionary convergence. Springer-Verlag, 1996 Taxaceae nationallicence Torreya nucifera nationallicence Megasporogenesis nationallicence megasporocyte nationallicence megaspore nationallicence Fiordi A. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut Lippi M. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut Marini S. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut Tani G. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut Plant Systematics and Evolution Springer-Verlag 202/1-2(1996-03-01), 13-25 0378-2697 202:1-2<13 1996 202 606 https://doi.org/10.1007/BF00985815 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00985815 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fiordi A. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut NATIONALLICENCE 700 1- Lippi M. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut NATIONALLICENCE 700 1- Marini S. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut NATIONALLICENCE 700 1- Tani G. Dipartimento di Biologia Vegetale, Via G. La Pira, 4, I-50121, Firenze, Italy aut NATIONALLICENCE 773 0- Plant Systematics and Evolution Springer-Verlag 202/1-2(1996-03-01), 13-25 0378-2697 202:1-2<13 1996 202 606 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer