Niedojadło Katarzyna, Hyjek Malwina, Bednarska-Kozakiewicz Elżbieta
Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Lwowska 1, 87-100, Toruń, Poland,
Plant Cell Rep. 2015 Jan;34(1):97-109. doi: 10.1007/s00299-014-1690-8. Epub 2014 Oct 8.
The composition of homogalacturonans (HGs) in the ovule and the female gametophyte cell walls was shown to be rearranged dynamically during sexual reproduction of H. orientalis. In angiosperms, homogalacturonans (HGs) play an important role in the interaction between the male gametophyte and the pistil transmitting tract, but little is known about the participation of these molecules at the final stage of the progamic phase and fertilization. The aim of our study was to perform immunocytochemical localization of highly (JIM7 MAb) and weakly (JIM5 MAb) methyl esterified and Ca(2+)-associated HG (2F4 MAb) in the ovule and female gametophyte cells of Hyacinthus orientalis before and after fertilization. It was found that pollination induced the rearrangement of HG in (1) the micropylar canal of the ovule, (2) the filiform apparatus of the synergids, and (3) the region of fusion between sperm cells and their target cells. Fertilization led to further changes in pectin composition of these three regions of the ovule. A new cell wall was synthesized around the zygote with a characteristic pattern of localization of all examined HG fractions, which we called "sporoderm-like". The developing endosperm prepared for cellularization by synthesizing highly methyl-esterified HG, which was stored in the cytoplasm. Pollination- and fertilization-induced changes in the composition of the HG in the micropyle of the ovule and the apoplast of female gametophyte cells are discussed in the context of: (1) micropylar pollen tube guidance, (2) preparation of the egg cell and the central cells for fusion with sperm cells, and (3) the polyspermy block.
东方风信子有性生殖过程中，胚珠和雌配子体细胞壁中的同型半乳糖醛酸聚糖（HG）组成呈现动态重排。在被子植物中，同型半乳糖醛酸聚糖（HG）在雄配子体与雌蕊传递组织的相互作用中发挥重要作用，但对于这些分子在配子体后期和受精阶段的参与情况却知之甚少。我们研究的目的是对受精前后东方风信子胚珠和雌配子体细胞中高度（JIM7单克隆抗体）和低度（JIM5单克隆抗体）甲酯化以及与Ca(2+)相关的HG（2F4单克隆抗体）进行免疫细胞化学定位。研究发现，授粉诱导了HG在以下部位的重排：（1）胚珠的珠孔道；（2）助细胞的丝状器；（3）精细胞与其靶细胞融合区域。受精导致胚珠这三个区域的果胶组成进一步变化。合子周围合成了一种具有所有检测到的HG组分特征定位模式的新细胞壁，我们将其称为“类孢子体壁”。发育中的胚乳通过合成高度甲酯化的HG为细胞化做准备，这些HG储存在细胞质中。本文结合以下方面讨论了授粉和受精诱导的胚珠珠孔和雌配子体细胞质外体中HG组成变化：（1）珠孔花粉管导向；（2）卵细胞和中央细胞为与精细胞融合做准备；（3）多精受精阻断。
