Rafińska Katarzyna, Świdziński Michał, Bednarska-Kozakiewicz Elżbieta
Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Lwowska 1, 87-100, Toruń, Poland.
Planta. 2014 Jul;240(1):195-208. doi: 10.1007/s00425-014-2074-6. Epub 2014 May 4.
Studies on angiosperm plants have shown that homogalacturonan present in the extracellular matrix of pistils plays an important role in the interaction with the male gametophyte. However, in gymnosperms, knowledge on the participation of HG in the pollen-ovule interaction is limited, and only a few studies on male gametophytes have been reported. Thus, the aim of this study was to determine the distribution of HG in male gametophytes and ovules during their interaction in Larix decidua Mill. The distribution of HG in pollen grains and unpollinated and pollinated ovules was investigated by immunofluorescence techniques using monoclonal antibodies that recognise high methyl-esterified HG (JIM7), low methyl-esterified HG (JIM5) and calcium cross-linked HG (2F4). All studied categories of HG were detected in the ovule. Highly methyl-esterified HG was present in the cell walls of all cells throughout the interaction; however, the distribution of low methyl-esterified and calcium cross-linked HG changed during the course of interaction. Both of these categories of HG appeared only in the apoplast and the extracellular matrix of the ovule tissues, which interact with the male gametophyte. This finding suggests that in L. decidua, low methyl-esterified and calcium cross-linked HG play an important role in pollen-ovule interaction. The last category of HG is most likely involved in adhesion between the pollen and the ovule and might provide an optimal calcium environment for pollen grain germination and pollen tube growth.
对被子植物的研究表明，雌蕊细胞外基质中的同型半乳糖醛酸聚糖在与雄配子体的相互作用中起重要作用。然而，在裸子植物中，关于同型半乳糖醛酸聚糖（HG）参与花粉 - 胚珠相互作用的知识有限，仅有少数关于雄配子体的研究报道。因此，本研究的目的是确定欧洲落叶松中HG在雄配子体和胚珠相互作用过程中的分布。使用识别高甲基酯化HG（JIM7）、低甲基酯化HG（JIM5）和钙交联HG（2F4）的单克隆抗体，通过免疫荧光技术研究了HG在花粉粒、未授粉和授粉胚珠中的分布。在胚珠中检测到了所有研究类型的HG。在整个相互作用过程中，高甲基酯化HG存在于所有细胞的细胞壁中；然而，低甲基酯化和钙交联HG的分布在相互作用过程中发生了变化。这两类HG仅出现在与雄配子体相互作用的胚珠组织的质外体和细胞外基质中。这一发现表明，在欧洲落叶松中，低甲基酯化和钙交联HG在花粉 - 胚珠相互作用中起重要作用。最后一类HG很可能参与花粉与胚珠之间的粘附，并可能为花粉粒萌发和花粉管生长提供最佳的钙环境。
