Microsporogênese e etapas da ontogenia do gametófito masculino de Tabebuia ochracea (Cham.) Standley (Bignoniaceae)

Abstract

RESUMO:(Microsporogênes e e etapas da ontogenia do gametófito masculino de Tabebuia ochracea (Cham.) Standley (Bignoniaceae)). Foram analisadas as etapas da ontogenia do gametófito masculino e da parede da antera de TlIbebuia ochracell. O método de formação da parede do microsporângio é do tipo Oicotiledôneo. O tecido esporogênico, em cada microsporângio, visto em secção transversal , organiza-se em uma fileira cel ular em forma de ferradura. O tapete é do tipo secretor e possui odgem dual. O tapete interno diferencia-se precocemente em relação ao tapete externo. As duas camadas tapetais são estruturalmente dimórficas, mas no fim do estágio pré-meiótico elas se tormam idênticas e com característico vacuoma bipolar. O endotécio desenvolve espessamentos helicoidais em suas paredes celulares. O desenvolvimento do pólen segue o modo usual em angiospermas. O expressivo crescimento do nucléolo e o aparecimento de vacúolos nucleolares na célula vegetativa sugerem sua alta atividade biossintetizante.Palavras-chaves: Bignoniaceae, Tabebuill, ontogenia, tapete , placentóide, micrósporos, gametófi-to masculino, pólen, vacúolos nucleolares.ABSTRACT: (Microsporogenes is and the early male gametophyte development ofTabebuill ochracelle (Cham.) Standley (Bignoniaceae)). Oevelopment of the pollen and anther wall of Tabebuia ocilracea was studied. The microsporangial wall follows the Dicotyledoneous type of ontogeny. The sporogenous tissue in each microsporangium, in transverse section, is organized in a celular strip, with a horseshoe outline. The tapetum is secretory and shows a distinct dual odgin. The inner tapetal layer differentiates earlier than the outher layer. The two tapetal layers exibit a distinct structural dimorphism, but before the meiotic divisions of the MMCs the tapetal layers become identical. Vacuolation in each tape tal cell, at this stage, is characteristically bipolar. The

AN OVERVIEW OF POLLEN AND ANTHER WALL DEVELOPMENT IN Catalpa bignonioides WALTER (BIGNONIACEAE)

“…However, in C. bignonioides, concurrent with the degeneration of the inner tangential walls of the tapetal cells, a new tapetal membrane was formed and Ubisch bodies attached to the inner surface of this tapetal membrane. Observations regarding the formation of tapetal membrane are consistent with the results of the previous studies including C. radicans (Tütüncü Konyar & Dane 2013b, Tütüncü Konyar 2014), J. mimosifolia (Galati & Strittmatter 1999a, 1999b, P. venusta , T. stans ) and T. ochracea (Bittencourt Jr. 1996).…”

“…The anthers of Catalpa bignonioides are tetrasporangiate as reported earlier for Catalpa bungei (Fan et al 2011 (Bittencourt Jr. 1996), T. pallida, (Shivaramiah 1981). However, bisporangiate anthers have also been reported in some members of Bignoniaceae comprising Jacaranda mimosifolia (Galati & Strittmatter 1999a).…”

“…At the free microspore stage, Ubisch bodies were observed on the inner tangential surface of the tapetal cells of C. bignonioides bordering the locules as reported earlier for C. radicans (Tütüncü Konyar & Dane 2013b, Tütüncü Konyar 2014), J. mimosifolia (Galati & Strittmatter 1999a, 1999b) P. venusta , T. stans , T. smithii (Shivaramiah 1981); T. ochracea (Bittencourt Jr. 1996), T. pulcherrima (Bittencourt Jr. & Mariath 1997) and in many other species of Bignoniaceae studied by Mehra & Kulkarni (1986). However, in C. bignonioides, concurrent with the degeneration of the inner tangential walls of the tapetal cells, a new tapetal membrane was formed and Ubisch bodies attached to the inner surface of this tapetal membrane.…”

“…Generally, the tapetal development in C. Bignoniodes is similar to other descriptions of the secretory tapetum in dicotyledons and in the other members of the Bignoniaceae. The tapetum in C. bignonioides anthers is of the secretory type and shows a distinct dual origin as in many other members of Bignoniaceae including C. bungei (Shivaramiah 1981), P. venusta , T. stans , T. smithii (Shivaramiah 1981), T. ochracea (Bittencourt Jr. 1996), T. pulcherrima (Bittencourt Jr. & Mariath 1997). On the other hand, amoeboid tapetum has also been reported in the other members of this family such as D. unguis-cati, K. africana and T. pallida (Shivaramiah 1981).…”

Poliembrionia e aspectos da embriogênese em Tabebuia ochracea (Chamisso) Standley (Bignoniaceae)

“…DC. (Mehra & Kulkarni 1985), T. ochracea (Bittencourt Júnior 1996, Gibbs & Bianchi 1993 e T. pulcherrima Sandw. (Bittencourt Júnior & Mariath 1997, 2002a.…”