Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development
The ovule of Tabebuia pulcherrima is anatropous, unitegmic and tenuinucellate. The nucellus shows a trizonate structural organization. The integument is initiated by periclinal divisions in the dermal layer (zone I), around the base of the archesporium. Subsequently, cells derived from the subdermal layer (zone II) start to push the dermal cells, so that they shift toward the micropylar region. The archesporial cell differentiates directly into the megaspore mother cell, undergoes meiosis, and originates a linear tetrad of megaspores. The mature embryo sac mother cell is elongated, possess a conspicuous central nucleus, and a characteristic bipolar vacuome with fibrous-granulated content. The inner cell layers of the integument differentiate into an amyloplast-rich endothelium. Patterns of callose deposition in the tetrad and selection of the functional megaspore, as well as the taxonomic value of some characters are discussed.
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Sociedade Botânica de São Paulo
2002
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oai:scielo:S0100-840420020001000132002-07-04Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument developmentBITTENCOURT JÚNIOR,NELSON S.MARIATH,JORGE E.A. Integument megasporogenesis ovule ontogeny Tabebuia Bignoniaceae The ovule of Tabebuia pulcherrima is anatropous, unitegmic and tenuinucellate. The nucellus shows a trizonate structural organization. The integument is initiated by periclinal divisions in the dermal layer (zone I), around the base of the archesporium. Subsequently, cells derived from the subdermal layer (zone II) start to push the dermal cells, so that they shift toward the micropylar region. The archesporial cell differentiates directly into the megaspore mother cell, undergoes meiosis, and originates a linear tetrad of megaspores. The mature embryo sac mother cell is elongated, possess a conspicuous central nucleus, and a characteristic bipolar vacuome with fibrous-granulated content. The inner cell layers of the integument differentiate into an amyloplast-rich endothelium. Patterns of callose deposition in the tetrad and selection of the functional megaspore, as well as the taxonomic value of some characters are discussed.info:eu-repo/semantics/openAccessSociedade Botânica de São PauloBrazilian Journal of Botany v.25 n.1 20022002-03-01info:eu-repo/semantics/articletext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042002000100013en10.1590/S0100-84042002000100013 |
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BITTENCOURT JÚNIOR,NELSON S. MARIATH,JORGE E.A. |
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BITTENCOURT JÚNIOR,NELSON S. MARIATH,JORGE E.A. Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development |
author_facet |
BITTENCOURT JÚNIOR,NELSON S. MARIATH,JORGE E.A. |
author_sort |
BITTENCOURT JÚNIOR,NELSON S. |
title |
Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development |
title_short |
Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development |
title_full |
Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development |
title_fullStr |
Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development |
title_full_unstemmed |
Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development |
title_sort |
ovule ontogeny of tabebuia pulcherrima sandwith (bignoniaceae): megasporogenesis and integument development |
description |
The ovule of Tabebuia pulcherrima is anatropous, unitegmic and tenuinucellate. The nucellus shows a trizonate structural organization. The integument is initiated by periclinal divisions in the dermal layer (zone I), around the base of the archesporium. Subsequently, cells derived from the subdermal layer (zone II) start to push the dermal cells, so that they shift toward the micropylar region. The archesporial cell differentiates directly into the megaspore mother cell, undergoes meiosis, and originates a linear tetrad of megaspores. The mature embryo sac mother cell is elongated, possess a conspicuous central nucleus, and a characteristic bipolar vacuome with fibrous-granulated content. The inner cell layers of the integument differentiate into an amyloplast-rich endothelium. Patterns of callose deposition in the tetrad and selection of the functional megaspore, as well as the taxonomic value of some characters are discussed. |
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Sociedade Botânica de São Paulo |
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2002 |
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http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042002000100013 |
work_keys_str_mv |
AT bittencourtjuniornelsons ovuleontogenyoftabebuiapulcherrimasandwithbignoniaceaemegasporogenesisandintegumentdevelopment AT mariathjorgeea ovuleontogenyoftabebuiapulcherrimasandwithbignoniaceaemegasporogenesisandintegumentdevelopment |
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