Gotelli Marina M, Lattar Elsa C, Zarvlasky Gabriela, Galati Beatriz G
Cátedra de Botánica General, Depto. de Recursos Naturales y Ambiente, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453 - C1417DSE, Buenos Aires, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas, Godoy Cruz 2290 (C1425FQB) CABA Buenos Aires, Argentina.
An Acad Bras Cienc. 2020 Nov 6;92(suppl 2):e20181382. doi: 10.1590/0001-3765202020181382. eCollection 2020.
The aim of this paper is to investigate the ultrastructural events that occur during pollen grains development, with emphasis in pollen grain wall and tapetum ontogeny in Ziziphus jujuba, Z. mucronata, Paliurus spina-christi (Paliureae) and Gouania ulmifolia (Gouanieae). Anthers at different developmental stages were processed according to classic techniques for transmission electron microscopy. Differences in the number of endothecium layers and in the number of tapetal cell nuclei were found. Tapetal cells present an anastomosing tubular network and large vesicles with fibrillar content in the cytoplasm. Pollen grain development and ontogeny of pollen grain wall are similar in the four species. The number of endothecium layers, the number of nuclei of the tapetal cells and tapetal cells ultrastructure of the four species support the phylogenetic relationships previously published for the Rhamnaceae family. Tapetal vesicles with fibrillar or polysaccharide content seem to be an exclusive characteristic of the tribes Paliureae and Gouanieae. Some ultrastructural characters of the pollen grain wall development are common to other species of Rhamnaceae, such as the primexine matrix present at the microspore mother cell stage, the aperture entirely built up during the tetrad stage, the thick and fibrillar intine, and the granular infractectum.
本文旨在研究枣、尖叶枣、马甲子（鼠李科）和榆叶鼠李（鼠李科）花粉粒发育过程中发生的超微结构变化，重点关注花粉粒壁和绒毡层的个体发育。根据传统的透射电子显微镜技术处理不同发育阶段的花药。发现药室内壁层数和绒毡层细胞核数量存在差异。绒毡层细胞呈现出吻合的管状网络，细胞质中有含纤维状物质的大液泡。这四个物种的花粉粒发育和花粉粒壁的个体发育相似。这四个物种的药室内壁层数、绒毡层细胞核数量和绒毡层细胞超微结构支持了先前发表的鼠李科的系统发育关系。含有纤维状或多糖物质的绒毡层液泡似乎是马甲子族和鼠李族的独特特征。花粉粒壁发育的一些超微结构特征在鼠李科的其他物种中也很常见，例如在小孢子母细胞阶段出现的原外壁基质、四分体阶段完全形成的萌发孔、厚且具纤维状的内壁以及颗粒状的内层。
