The transcriptional and posttranscriptional AGO-mediated control of gene expression may play important roles during male monocot gametophyte development. In this report, we demonstrated dynamic changes in the spatiotemporal distribution of AGO1 and AGO4, which are key proteins of the RNA-induced silencing complex (RISC) in Hyacinthus orientalis male gametophyte development. During maturation of the bicellular pollen grains and in vitro pollen tube growth, the pattern of AGO1 localization was correlated with previously observed transcriptional activity of the cells. During the period of high transcriptional activity, AGO1 is associated with chromatin while the clustered distribution of AGO1 in the interchromatin areas is accompanied by condensation of chromatin and the gradual transcriptional silencing of both cells in mature, dehydrated pollen. During pollen tube growth and the restarting of RNA synthesis in the vegetative nucleus, AGO1 is dispersed in the chromatin. Additionally, the gradual increase in the cytoplasmic pool of AGO1 in the elongating pollen tube indicates the activation of the posttranscriptional gene silencing (PTGS) pathway. During pollen tube growth in the generative cell and in the sperm cells, AGO1 is present mainly in the areas between highly condensed chromatin clusters. Changes in the distribution of AGO4 that indicated the possibility of spatiotemporal organization in the RNA-directed DNA methylation (RdDM) process (cytoplasmic and nuclear steps) were also observed during hyacinth male gametophyte development. Based on our findings, we propose that in the germinating pollen tube, the cytoplasmic assembly of AGO4/siRNA takes place and that the mature complexes could be transported to the nucleus to carry out their function during the next steps of pollen tube growth.

中文翻译：

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ARGONAUTE1（AGO1）和ARGONAUTE4（AGO4）在风信子花粉粒和花粉管体外生长的动态分布

转录和转录后 AGO 介导的基因表达控制可能在雄性单子叶植物配子体发育过程中发挥重要作用。在本报告中，我们展示了 AGO1 和 AGO4 时空分布的动态变化，它们是风信子雄配子体发育中 RNA 诱导的沉默复合物 (RISC) 的关键蛋白质。在双细胞花粉粒成熟和体外花粉管生长过程中，AGO1 定位模式与先前观察到的细胞转录活性相关。在高转录活性时期，AGO1与染色质相关，而AGO1在染色质间区域的簇状分布伴随着染色质的凝聚和成熟脱水花粉中两个细胞的逐渐转录沉默。在花粉管生长和营养核中 RNA 合成重新开始期间，AGO1 分散在染色质中。此外，伸长的花粉管中 AGO1 细胞质库的逐渐增加表明转录后基因沉默 (PTGS) 途径的激活。在生殖细胞和精子细胞的花粉管生长过程中，AGO1 主要存在于高度浓缩的染色质簇之间的区域。在风信子雄配子体发育过程中还观察到 AGO4 分布的变化，表明 RNA 指导的 DNA 甲基化 (RdDM) 过程（细胞质和核步骤）中时空组织的可能性。根据我们的发现，我们建议在发芽的花粉管中，