Female Gametophyte in Tristichoideae (Podostemaceae): Re-Investigation
نویسندگان
چکیده
منابع مشابه
Phylogenetic Relationship and Morphology of Dalzellia Gracilis (podostemaceae, Subfamily Tristichoideae) with Proposal of a New Genus
Dalzellia gracilis, an enigmatic species of Podostemaceae, is characterized by the subcylindrical creeping roots and dorsiventral ribbonlike shoots borne on the roots. To reveal the phylogenetic relationships of D. gracilis, molecular phylogenetic and morphological analyses were performed. A matK tree indicates that it is most likely sister to a clade of its congeners and Indotristicha ramosiss...
متن کاملFemale gametophyte development.
Early in their evolution, plants acquired a life cycle that alternates between a multicellular haploid organism, the gametophyte, and a multicellular diploid organism, the sporophyte. Angiosperms have both female and male gametophytes. The female gametophyte is critical to many steps of the angiosperm reproductive process, including pollen tube guidance, fertilization, the induction of seed dev...
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The anther, pollen and ovule development in Achillea tenuifolia were studied with a bright field microscopy. Results showed that the anther is of tetrasporangiate type and the anther wall is composed by four layers: an epidermis, an endothecium, one middle layer and a tapetum layer. Tapetum is of secretory type and its cells showed polyploidy. Pollen tetrads were tetrahedral, microspores were v...
متن کاملPollen tube guidance by the female gametophyte.
In flowering plants, pollen grains germinate on the pistil and send pollen tubes down the transmitting tract toward ovules. Previous genetic studies suggested that the ovule is responsible for long-range pollen tube guidance during the last phase of a pollen tube's journey to the female gametes. It was not possible, however, to unambiguously identify the signaling cells within an ovule: the hap...
متن کاملFemale gametophyte-controlled pollen tube guidance.
During the evolution of flowering plants, their sperm cells have lost mobility and are transported from the stigma to the female gametophyte via the pollen tube to achieve double fertilization. Pollen tube growth and guidance is largely governed by the maternal sporophytic tissues of the stigma, style and ovule. However, the last phase of the pollen tube path is under female gametophyte control...
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ژورنال
عنوان ژورنال: Journal of Biological Sciences
سال: 2008
ISSN: 1727-3048
DOI: 10.3923/jbs.2008.1158.1165