Laboratory of Algae and Plants of Amazonia (LAPAM), Federal University of Oeste do Pará (UFOPA) Campus Oriximiná, Rodovia PA-254, 257, Oriximiná, PA, Brazil.
Laboratory of Electron Microscopy and Microanalysis (LMEM), State University of Londrina (UEL), 86057-970, PR, Brazil.
Micron. 2021 Jan;140:102962. doi: 10.1016/j.micron.2020.102962. Epub 2020 Oct 14.
Microsporogenesis and microgametogenesis are unusual in sedges (Cyperaceae), the third largest monocotyledonous family, as three microspores are aborted in favor of a single functional microspore. However, studies using light microscopy show that megasporogenesis and megagametogenesis occur normally. Nevertheless, the lack of ultrastructural details limits our knowledge of female gametophyte development in this family. Given the importance of morphological studies of reproductive structures, ovules and megagametophytes of Rhynchospora pubera were analyzed under transmission electron microscopy for the first time. Overall, ovules presented features similar to those described for the family, but ultrastructural details revealed an absence of a clear boundary between the egg cell and the central cell cytoplasm. Most interestingly, antipodal and nucellar cells showed several signs of vacuolar cell death, which suggest that programmed autolysis in sporogenous and gametophytic tissue is common in gametophyte development in the Cyperaceae. This may be related to the reproductive success of this family.
小孢子发生和小配子发生在莎草科（Cyperaceae）中是不寻常的，莎草科是单子叶植物的第三大科，因为三个小孢子退化，有利于单个功能小孢子的形成。然而，使用光学显微镜的研究表明，大孢子发生和大配子发生正常发生。尽管如此，缺乏超微结构细节限制了我们对该科雌性配子体发育的了解。鉴于生殖结构形态学研究的重要性，首次对 Rhynchospora pubera 的胚珠和大配子体进行了透射电子显微镜分析。总的来说，胚珠表现出与该科描述的特征相似，但超微结构细节显示卵母细胞和中央细胞质之间没有明确的边界。最有趣的是，反足细胞和珠心细胞表现出几个液泡细胞死亡的迹象，这表明在孢子发生和配子体组织中的程序性细胞自溶在 Cyperaceae 的配子体发育中很常见。这可能与该科的生殖成功有关。
