TAPETAL ORIGIN OF POLLEN‐COAT SUBSTANCES IN <i>LILIUM</i>

Heslop‐Harrison, J.

doi:10.1111/j.1469-8137.1968.tb06395.x

Cited by 140 publications

(48 citation statements)

References 14 publications

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“…Observou-se a ruptura de células tapetais após o desmembramento das tétrades, com conseqüente liberação do conteúdo protoplasmático no fluido locular, o que está relacionado com a transferência do "Pollenkitt" e do trifino, do tapete para a superfície dos grãos de pólen (Heslop-Harrison 1968, 1975aDickinson & Lewis 1973;Pacini et aI. 1985;Chapman 1987).…”

Section: Discussionunclassified

Ontogenia dos estratos parietais da antera de Tabebuia pulcherrima Sandw. (Bignoniaceae)

Bittencourt

Mariath

1997

Acta Bot. Bras.

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RESUMO -(Ontogenia dos estratos parietais da antera de Tabebuia pulcherrima Sandw. (Bignoniaceae)). A ontogenia do tapete e dos demais estratos parietais, bem como o desenvolvimento do estômio e deiscência da antera de Tabebuia pulcherrima, foram presentemente estudados. O padrão de formação da parede do androsporângio é do tipo Dicotiledôneo. A camada parietal primária, a camada esporogênica e o tapete interno derivam-se diretamente do meristema fundamental. O tecido esporogênico, em cada androsporângio, visto em secção transversal, organiza-se numa fileira celular em forma de ferradura. O tapete é do tipo secretor e possui origem dual. O tapete interno diferencia-se precocemente em relação ao tapete externo. As duas camadas tapetais são discretamente dimórficas, mas tal dimorfismo é perdido no fim do estádio meiótico do esporângio. O dimorfismo tapetal e a precoce diferenciação do tapete interno são interpretados como expressão de um lapso ontogenético entre as duas camadas. Nas regiões dorso-laterais das tecas desenvolve-se um endotécio multiestratificado com espessamentos anelados ou helicoidais nas paredes celulares. A deiscência é precedida pela degeneração dos tecidos placentóides e ruptura dos septos interesporangiais. Apenas as células epidérmicas dos dois lados do sítio de ruptura do estômio (células estomiais) estão envolvidas com a ruptura do mesmo.Palavras-chave: Bignoniaceae, Tabebuia, tapete, deiscência, ontogenia.ABSTRACT -(Ontogeny of the anther parietal layers of Tabebuia pulcherrima Sandw. (Bignoniaceae» . The ontogeny of the tapetum and parietal layers, as well as the stomium development and the dehiscence of the anther of Tabebuia pulcherima was studied. The anther wall formation follows the Dicotyledoneous type. The primary parieta! layer, the sporogenous tissue, and the inner tapetum are differentiated directly from the ground meristem. The sporogenous tissue, as seeing in a transverse section, is organized in one cellular strip with a horseshoe outline. The tapetum is secretory and shows a distinct dual origino The inner tapetal layer differentiates earlier than the outher. The two tapetallayers are moderately dimorphic. However, I Parte da dissertação de Mestrado do primeiro autor 2 Centro de Ciências da Saúde, Universidade do Vale do Rio dos Sinos. Av. UNISINOS 950, CEP 93.022-000, São Leopoldo, Rio Grande do Sul, Brasil. Ex-bolsista da CAPES

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Section: Discussionunclassified

Ontogenia dos estratos parietais da antera de Tabebuia pulcherrima Sandw. (Bignoniaceae)

Bittencourt

Mariath

1997

Acta Bot. Bras.

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“…The lipidic pollen coating is the material remaining after tapetal breakdown that sticks to the sculptured exine (Heslop-Harrison, 1968;Dickinson, 1973;Dickinson and Lewis, 1973a;Evans et al, 1992). At anther dehiscence, the coating material is retracted into the exine cavities because of drying.…”

Section: Introductionmentioning

confidence: 99%

“…More likely, they are released at the tapetal rupture together with the lipidic residues of the tapetum into the locule. Here, they coat the developing pollen grains (Heslop-Harrison, 1968;Dickinson, 1973;Dickinson and Lewis, 1973a;Murgia et ai., 1991). The hydrophobic do main of the proteins might bind them to oil bodies in the tapetum.…”

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Characterization of Oleosins in the Pollen Coat of Brassica oleracea

Ruiter¹,

Eldik²,

Herpen³

et al. 1997

The Plant Cell

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Mature Brassica oleracea pollen grains are covered with a lipophilic pollen coat containing a variety of proteins. Screening of an anther cDNA expression library for the coding sequences of such proteins resulted in the isolation of a number of cDNA clones encoding glycine-rich oleosins. The proteins were shown to be attached to the lipophilic coat material only and to be absent elsewhere in the plant. Within the coat, several forms of the pollen coat oleosin with dif ferent molecular weights were detected. The forms are encoded by different transcripts that originate from a single gene. Expression of this gene is restricted to the tapetum and is quantitatively regulated by the water content of the an ther. Similar oleosins were found in the pollen coat of B. aibogtobra and B. napus.

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“…2 B,C). The position of pollen apertures is believed to be set during microsporocyte cytokinesis (Heslop-Harrison, 1968b). The primexine precursors are synthesized and secreted by the microsporocytes to the pollen surface (Scott et al, 1991a; Fitzgerald and Knox, 1995) and may work as a scaffold for polymerization of fatty acids and phenolics on the surface (Sheldon and Dickinson, 1983;Scott et al, 1991a;Scott, 1994).…”

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The making of gametes in higher plants

Boavida¹,

Becker²,

Feijó³

2005

Int. J. Dev. Biol.

104

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Higher plants have evolved to be one of the predominant life forms on this planet. A great deal of this evolutionary success relies in a very short gametophytic phase which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower. In most species the processes of gametogenesis, pollination, syngamy and embryogenesis are sequentially coordinated to give rise to a functional seed in a matter of few weeks. Any of these processes is so intricately complex and precisely regulated that it becomes no wonder that each involves more specific genes and cellular processes than any other function in the plant life cycle. While variability generation -the evolutionary output of the sexual cycle -is the same as in any other Kingdom, plants do it using a completely original set of mechanisms, many of which are not yet comprehended. In this paper, we cover the fundamental features of male and female gametogenesis. While the physiological and cellular bases of these processes have been continuously described since the early nineteen century, recent usage of Arabidopsis and other species as central models has brought about a great deal of specific information regarding their genetic regulation. Transcriptomics has recently enlarged the repertoire and pollen became the first gametophyte to have a fully described transcriptome in plants. We thus place special emphasis on the way this newly accumulated genetic and transcriptional information impacts our current understanding of the mechanisms of gametogenesis. KEY WORDS: pollen, embryo sac, gametogenesis, microsporogenesis, macrosporogenesis The uniqueness of a life formOne of the most remarkable features of life on earth is diversity, a great deal of which is based on the evolutionary output of sexual reproduction. Unlike animals, in which the primordial germ line develops early during embryogenesis, higher plants alternate the growth of the diploid sporophyte organism with a highly reduced growth form on the plant life cycle, the haploid gametophyte. This is a well-suited strategy for selection because plants spend most of their life on the vegetative phase. The gametophytic stage also presents an opportunity for selection at the haploid level (Ottaviano et al., 1990).Plant cells don't move and positional information instead of lineage is the primary determinant of cell fate in plants. Meiosis triggers the separation between sporophytic and gametophytic generations involving various genes (Caryl et al., 2003). This spatial pleiotropy of the sexual organs has prompted evolution for the appearance of safety mechanisms to prevent the fusion of incompatible genomes while supporting genetic variability. In higher animals genetic mechanisms for sex determination establish striking developmental differences between males and feInt. J. Dev. Biol. 49: 595-614 (2005) doi: 10.1387/ijdb.052019lb males. In contrast, most higher plant species develop both male and female structures within the same flower, allowing selffertilizati...

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TAPETAL ORIGIN OF POLLEN‐COAT SUBSTANCES IN LILIUM

Cited by 140 publications

References 14 publications

Ontogenia dos estratos parietais da antera de Tabebuia pulcherrima Sandw. (Bignoniaceae)

Ontogenia dos estratos parietais da antera de Tabebuia pulcherrima Sandw. (Bignoniaceae)

Characterization of Oleosins in the Pollen Coat of Brassica oleracea

The making of gametes in higher plants

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